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Basic Microbiology
 

Basic Microbiology

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Basic Microbiology

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    Basic Microbiology Basic Microbiology Presentation Transcript

    • BASIC MICROBIOLOGY http://crisbertcualteros.page.tl
    • RULES IN GRAM STAINING
      • Most cocci are Gram positive EXCEPT:
      • Neisseria
      • Moraxella
      • Veillonella
      • Spirochetes are a negative
      Most bacilli are GRAM NEGATIVE except B 2 – Bacillus, Bifidobacterium A - Actinomyces N - Nocardia S - Streptomyces C 2 - Clostridium, Corynebacterium E - Erysipelothrix L 2 - Listeria, Lactobacillus
    • Actinomyces israelii
    • Bacteria Not Seen by Gram staining Giemsa or other tissue stain Intracellular, Very small Rickettsiae Inclusion bodies in cytoplasm Intracellular, very small Chlamydiae None No cell wall M. pneumoniae Darkfield micro/ Fluorescent micro Too thin to see Spirochetes Acid-fast stain High lipid in cell wall Mycobacteria Alternative Reason Name
    • ACID-FAST STAINING
      • Carbol fuchsin method
        • Ziehl-Neelsen Method
        • Kinyoun Method
        • C arbol fuchsin
        • A cid alcohol,
        • M ethylene blue/malachite green
        • Acid-fast: red
        • Non-acid-fast: blue or green
      • Fluorochrome method
        • Auramine/rhodamine
        • Acid-alcohol
        • K permanganate
      • Fluorescent microscope
    • Acid-fast organisms
      • Mycobacterium spp.
      • Nocardia spp. (partial)
      • Legionella micdadae
      • Cryptosporydium
      • Isospora
      • Genes can be transmitted between bacteria by each of the following processes/ except:
      • generalized transduction
      • conjugation
      • C. transversion
      • D. lysogenic conversion
      • Which of the following is responsible for the passage of low molecular weight solutes through the outer membrane of Gram negative bacteria?
      • Capsules
      • Endospores
      • Mesosomes
      • porins
      • Bacteria which are able to grow at temperature below 25 o C are called
      • halophiles C. psychrophiles
      • osmophiles D. thermophiles
      • 7. Most of the bacteria pathogenic to man are
      • A. halophilic C. psychrophilic
      • B. aerophilic D. thermophilic
    • TYPICAL BACTERIAL CELL
    • BACTERIAL STRUCTURE Adherence to surfaces Polysaccharide Glycocalyx vs. phagocytosis Polysaccharide Capsule Division septa Invagination of c.m. Mesosome Hydrolytic enzymes (phosphatases, B-lactamases, etc) Space between c.m. and o.m. Periplasm Osmotic barrier Oxidative and transport enzymes Lipid bilayer Cyto. membrane Endotoxin O antigen Lipid A Somatic O polysaccharide Outer membrane (porin, LPS) Rigid support Protection vs. osmotic pressure peptidoglycan Cell wall 1 , 2 , 3 Function Chem Comp Structure
    • BACTERIAL STRUCTURE Motility Protein (flagellin): basal body, hook, filament Flagellum Motility of spirochetes Axial filaments Common: attach to cell surface Sex: conjugation Glycoprotein (pilin) Pilus/fimbriae Storage of food and energy Glycoprotein, lipids, polyphosphates Granule Resistance to drying, heat, chemicals, UVL Keratin-like coat, dipicolinic acid Endospore Genes for antibiotic R, toxins DNA Plasmid Genetic material DNA Nucleoid Function Chem Comp Structure
    • CELL WALL
      • Peptidoglycan
      • Glycan:
        • N-Ac-glucosamine
        • N-Ac-muramic acid
      • Tetrapeptide
      • Crosslink – peptide bridges
    • Cell Wall-less Forms
      • Treated with lysozyme or antibiotic (e.g., penicillin)
      • Protoplasts – from gram positive cells
      • Spheroplasts – from gram negative cells
      • L-forms – genetically cell wall-containing
        • capable of regenerating the cell wall
        • may be formed spontaneously
        • produce chronic infections
        • relatively resistant to antibiotics
      • Mycoplasma – inherently cell wall-less
    • COMPARISON BETWEEN GRAM POSITIVE AND GRAM NEGATIVE BACTERIA
      • Gram positive:
        • very thick peptidoglycan layers
        • contains techoic acids
      • Gram negative:
        • thinner cell wall
        • covered by an outer membrane
        • Has periplasmic space
    • ENDOSPORES
      • Bacillus, Clostridium, Coxiella
      • For survival in adverse environment:
        • Heat, drying, chemicals, UVL, depelted nutrients
      • Dehydrated
      • Dipicolinic acid
      • Metabolically inactive
      • Not for reproduction
      • Each of the following statements concerning bacterial and human cells is correct EXCEPT
      • A. Bacteria are prokaryotic (ie, they have one molecule of DNA, are haploid, and have no nuclear membrane)
      • B. Bacteria derive their energy by oxidative phosphorylation within the mitochondria in manner similar to human cells
      • C. Bacterial and human ribosomes are of different sizes and chemical compositions
      • D. Bacterial cells possess peptidoglycan, whereas human cells do not
      • Cell envelopes of both gram positive and gram-negative bacteria are composed of complex macromolecules. Which of the following statements describes both gram-positive and gram-negative cell envelopes?
        • A. They contain a significant amount of teichoic acid
        • B. They contain all the common amino acids
        • C. Their antigenic specificity is determined by the polysaccharide O antigen
        • D. They are a diffusion barrier to large charged molecules
      • Each of the ff statements concerning the surface structures of bacteria is correct EXCEPT
        • A. Pili mediate the interaction of bacteria with mucosal epithelium
        • B. Polysaccharide capsules retard phagocytosis
        • C. Both gram-negative rods and cocci have polysaccharides (endotoxin) in their cell wall
        • D. Bacterial flagella are non-antigenic in humans because they closely resemble human flagella in chemical composition
      • An aliquot of Escherichia coli is treated with EDTA. The first wash is analyzed and found to contain alkaline phosphatase, DNAse, and penicillinase. The anatomic area of the cell affected is most likely to have been the
        • Periplasmic space
        • Mesosomal space
        • chromosome
        • plasma membrane
      • L forms are correctly characterized as:
      • A. generally susceptible to amphotericin B
      • B. unable to revert to their bacterial parental types
      • C. not induced by penicillin or ultraviolet light
      • D. containing sterols in the membrane
      • The fine filamentous appendages, arising from basal bodies in the cytoplasmic membrane of many gram negative bacilli are known as
      • spores
      • mesosomes
      • pili
      • capsules
      • flagella
      • The toxic property of endotoxin lies in the
      • A. protein C D. O antigen
      • B. polysaccharide core E. lipid A
      • C. protein A
      • Septicemic shock from Gram-negative rods is triggered by
      • endotoxin
      • exotoxin
      • Chemotaxis
      • exaggerated immune response
      • immune complexes
      • The substance which is responsible for producing endotoxic shock is
      • enterotoxin P of Staphylococcus aureus
      • pyocyanin of Pseudomonas aeruginosa
      • protein M of Streptococcus pyogenes
      • lipid A of Neisseria meningitidis
      • the polysaccharide capsule of Hemophilus influenzae
    • GROWTH REQUIREMENTS OF BACTERIA
      • 1. Source of Carbon and Nitrogen
      • autotrophs - use inorganic compounds
      • -photolithotroph – light as energy source
      • -chemolithotroph – chemical rxns as energy source
      • heterotrophs - use organic compounds
      • -photoorganotroph – light as energy source
      • -chemoorganotroph - chemical rxns as energy source
      • 2. Vitamins and minerals
      • 3. Amino acids
      • 4. Water
      • 5. pH - 7.2 to 7.6
    • GROWTH REQUIREMENTS OF BACTERIA
      • 6. Temperature -
      • psychrophile – 0-20 C
      • mesophile – 20-40 C
      • thermophile – 40-80 C
      • 7. Oxygen
      • obligate aerobes
      • obligate anaerobes
      • facultative aerobes/anaerobes
      • microaerophiles
      • aerotolerant
      • O 2
      • O -2
      • SOD
      • H 2 O 2
      • catalase
      • H 2 O + O 2
    • Obligate Anaerobes
      • Sporeforming – Clostridium
      • Non-sporeforming
        • Bacteroides
        • Fusobacterium
        • Bifidobacterium
        • Lactobacillus
        • Actinomyces
        • Propionibacterium
        • Peptococcus
        • Peptostreptococcus
        • Veillonella
      • Nonsporeforming anaerobes:
      • normal flora: mouth, URT, GIT, CUT
      • Require low redox potential
      • Polymicrobic infection
    • Bacterial Growth Curve # viable cells time a b c d a- Lag phase b- Logarithmic phase c- stationary phase d- decline phase
      • Optimum pH for growth of most bacteria is
      • A. 5.5-6.5 C. 8.0-9.3.
      • B. 7.2-7.6 D. none of the above
      • Oxygen is toxic to
      • facultative anaerobes
      • obligate anaerobes
      • aerotolerant anaerobes
      • none of the above
      • Bacteria that make either a fermentative or respiratory set of enzymes are known as
      • A. facultative organism C. microaerophiles
      • B. obligate aerobes D. obligate anaerobes
      • Bacteria which are able to grow at temperature below 25 o C are called
      • A. halophiles C. osmophiles
      • B. psychrophiles D. thermophiles
      • Which is LEAST acceptable as specimen for the diganosis of anaerobic infections?
      • Transtracheal aspirate
      • Suprapubic aspirate
      • Vaginal swab
      • Sample from tissue of infected site
      • What do you call the stage of growth where there is slow loss of cells through death that is just balanced by the formation of few cells through growth and division?
        • A. Acceleration C. lag
        • B. Maximum stationary D. exponential
      • Which is NOT anaerobic?
      • Fusobacterium D. Clostridium
      • Bacteroides E. Peptostreptococcus
      • Branhamella
    • STERILIZATION AND DISINFECTION
    • STERILIZATION-DISINFECTION
      • STERILIZATION- the process of destroying all forms of life including spores
      •  
      • DISINFECTION - does not necessarily destroy all forms of life but aims to destroy the disease-producing organisms
      •  
      • DISINFECTANT - chemical agent used inanimate objects
      •  
      • ANTISEPTIC - chemical agent used to kill organisms on the surface of skin and mucous membrane
    • STERILIZATION-DISINFECTION
      • A. HEAT: denature proteins, membrane damage or DNA cleavage
      • 1. MOIST HEAT:
      • a. BOILING: spores are resistant
      • b. STEAM UNDER PRESSURE ( autoclaving)
      • -121 C at 15 psi for 15-20 minutes
      • -kills spores
      • c. PASTEURIZATION
      • - 62 C for 30 min. or;
      • - 72 C for 15 sec.
      PHYSICAL AGENTS
    • STERILIZATION-DISINFECTION
      • 2. DRY HEAT:
      • a. HOT AIR OVEN - 170 - 180 C for 2 hrs
      • -sporocidal
      • b. open flame
      • c. incineration
      PHYSICAL AGENTS
    • STERILIZATION-DISINFECTION
      • B. RADIATION:
      • -UVL - formation of pyrimidine dimers (DNA)
      • - 240 - 280 nm.
      • -X-RAYS, GAMMA RAYS, ETC. - production of free radicals
      •  
      • C. FILTRATION - preferred for certain liquids that are heat-sensitive like serum, enzyme solutions
      • -membrane filters: 0.22  m
      PHYSICAL AGENTS
    • STERILIZATION-DISINFECTION
      • D. LYOPHILIZATION
      • - freeze-drying
      • - rapid freezing and sublimating the ice in a
      • vacuum
      • -preservation of cultures (bacteriostatic)
      •  
      • E. REFRIGERATION - bacteriostatic
      • F. FREEZING - bacteriostatic
      PHYSICAL AGENTS
    • STERILIZATION-DISINFECTION
      • A. DISRUPTION OF CELL MEMBRANES
      • ALCOHOLS
      • PHENOL - standard for new chemical agents
      • CRESOL
      • HEXACHLOROPHENE
      • DETERGENTS
      •  
      • B. DENATURE PROTEINS
      • ALCOHOLS
      • PHENOL
      • ACIDS AND ALKALIS
      CHEMICAL AGENTS
    • STERILIZATION-DISINFECTION
      • C. MODIFICATION OF PROTEINS & NUCLEIC ACID
      • 1. HEAVY METALS - oxidizing agents
      • MERCURY - merthiolate, mercurochrome
      • SILVER - silver nitrate
      • 2. HALOGENS - SPOROCIDAL
      • -oxidizing agent: form S-S bonds from -SH groups
      • CHLORINE - purify water supply
      • -active component of hypochlorites
      • IODINE - MOST EFFECTIVE SKIN ANTISEPTIC
      • -TINCTURE OF IODINE - irritating
      • -IODOPHORS - less irritating
      CHEMICAL AGENTS
    • STERILIZATION-DISINFECTION
      • 3. HYDROGEN PEROXIDE
      • -oxidize -SH groups
      • 4. ALDEHYDES - alkylate proteins and nucleic acids
      • -SPOROCIDAL
      • FORMALDEHYDE
      • GLUTARALDEHYDE - 10X more effective than
      • formaldehyde
      • -cold sterilant
      • -sterilization of heat-sensitive instruments
      • 5. ETHYLENE OXIDE - alkylating agent
      • -gas
      • -SPOROCIDAL
      • -sterilization of heat-sensitive instruments
      CHEMICAL AGENTS
    • Antimicrobial Agents Drugs Mechanism of Action Penicillins, cephalosporins, imipenem, aztreonam, bacitracin, vancomycin, cycloserine Inhibition of cell wall synthesis Chloramphenicol, erythromycin, clindamycin Aminoglycosides, tetracyclines Inhibition of Protein synthesis Bind to 50S ribosomal subunit Binds to 30S ribosomal subunit -Sulfonamides, trimethoprim -quinolones, novobiocin, Metronidazole Rifampin Inhibition of nucleic acid synthesis Inhibition of nucleotide synthesis Inhibition of DNA synthesis Inhibition of mRNA synthesis
    • Antimicrobial Agents Drugs Mechanism of Action Alteration of Cell Membrane Polymyxin Antibacterial Isoniazid Others Inhibits mycolic acid synthesis Amphotericin B, nystatin, ketoconazole Antifungal
    • Figure 5-9 Mechanisms of bacterial gene transfer. (From Rosenthal KS, Tan J: Rapid reviews microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 24 September 2006 05:26 AM) © 2005 Elsevier Transformation -the transfer of naked or free DNA -requires competence of recipient cell
    • Figure 5-9 Mechanisms of bacterial gene transfer. (From Rosenthal KS, Tan J: Rapid reviews microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 24 September 2006 05:26 AM) © 2005 Elsevier Transduction - the transfer mediated by a bacteriophage
    • Figure 5-9 Mechanisms of bacterial gene transfer. (From Rosenthal KS, Tan J: Rapid reviews microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 24 September 2006 05:26 AM) © 2005 Elsevier Conjugation -the transfer of DNA thru a cell-to-cell contact -usually involves the sex pilus
      • Strong mineral acids and alkalis
      • A. have an antiseptic effect
      • B. are both contained in Lysol
      • C. have a disinfectant effect
      • D. have no relationship to their dissociation in solution
      • The most effective method of sterilization by heat is
      • A. steam under pressure C. hot air oven
      • B. boiling D. live steam
      • Many of this type of bacteria do not possess superoxide dismutase and catalase
      • Obligate aerobes
      • Obligate anaerobes
      • Facultative anaerobes
      • microaerophiles
      • It is the period when the bacterium is assessing the nutrients present in the medium; the bacterium does not divide but there is a intense metabolic activity. The phase of growth is
      • Lag
      • Logarithmic
      • Stationary
      • Decline
      • These are groups of genes that are clustered together in the DNA of some bacterial species and which may enable them to invade a host
      • Pathogenicity island
      • Episomes
      • Transposons
      • Replicons
      • Which is true about the bacterial chromosome?
      • Contains histones that stabilize the DNA
      • Composed of a single pair of homologous chromosomes
      • Replicates in a very different manner from that of the eukaryotic chromosomes
      • Contain single copy of each gene
      • A non-encapsulated strain of Hemophilus influenzae acquires the gene for capsule production from a DNA extract of an encapsulated strain. The event that has occurred is
      • Transformation
      • Conjugation
      • Transduction
      • transversion
      • A hospitalized patient with dysuria and suprapubic pain is teated with ciprofloxacin.This antibiotic acts by inhibiting
      • DNA-dependent RNA polymerase
      • Protein synthesis by binding with 30S ribosomal subunit
      • Protein synthesis by binding with 50S ribosomal subunit
      • Topoisomerase II
      • Which is the predominant indigenous flora of the colon?
      • anaerobic, gram negative, non-sporeforming bacteria
      • anaerobic, gram positive, non-sporeforming bacteria
      • aerobic, gram negative, non-sporeforming bacteria
      • aerobic, gram positive, sporeforming bacteria
      • Gaseous sterilization employs which of the following substances?
      • A. rocal D. hexachlorophene
      • B. ethylene oxide E. iodophor
      • C. glutaraldehyde
      • Contaminated wound dressings are sterilized best by
      • A. boiling in water for 1 hour
      • B. immersion in a quaternary ammonium compound
      • C. autoclaving for 20 minutes
      • D. exposure to a germicidal ultraviolet light
      • E. soaking' in 70 percent ethanol for 2 hours
      • If an agent is introduced into a growing bacterial colony, cell multiplication ceases; removal of the agent however, allows bacterial cell division to resume. This agent may be described as
      • A. a disinfectant C. a bacteriostat
      • B. a bactericide D. an antiseptic
      • Procedure where organisms are frozen rapidly and dehydrated in a high vacuum container is called
      • A. Tyndallization C. cephalization
      • B. Saponification D. lyophilization
      • Limited primarily to the testing of new bactericidal agents:
      • A. Zephiran C. benzalkoniun chloride
      • B. phenol D. Tween 80
      • The phenol coefficient is
      • A. a method used to test the bacteriological power of phenol
      • B. the lowest dilution of unknown disinfectant that kills all types of organisms
      • C. the highest dilution of unknown disinfectant that kills all types of organisms
      • D. the standardization of disinfectant by comparison with the lethal action of phenol
      • Resistance of bacteria to antibiotic is due to
      • A. chromosomal changes C. plasmids
      • B. episomes D. all of the above
      • The indication for the use of two or more antimicrobials simultaneously are as follows, EXCEPT:
      • A. to mask serious infections
      • B. to delay the emergence of resistant mutants
      • C. for mixed infection
      • D. to achieve bacterial synergism
      • Each of the following statements concerning the mechanism of action of antimicrobial drugs is correct EXCEPT
      • A. Vancomycin acts by inhibiting peptidoglycan synthesis
      • B. Quinolones, such as ciprofloxacin, act by inhibiting the DNA gyrase of bacteria
      • C. Erythromycin is a bacterial drug that disrupts cell membranes by a detergent-like action
      • D. Aminoglycosides such as streptomycin are bactericidal drugs that inhibit protein synthesis
      • A gynecologist wants the hospital to sterilize her fragile stainless steel instruments in preparation for a surgery. Which of the following is the most practical for this purpose?
      • Wipe well with hypochlorite solution
      • Spray with ethylene oxide gas
      • Expose to UVL overnight
      • Soak in glutaraldehyde solution, then rinse with sterile water
    • NORMAL FLORA
      • Most common organism
      • SKIN - S. epidermidis
      • NOSE - S. aureus
      • MOUTH -
      • - oropharynx – Viridans streptococci
      • - gingival crevices - Anaerobes
      • COLON
      • -adults: OBLIGATE ANAEROBES ( Bacteroides )
      • -breastfed baby: Bifidobacterium
      • -formula-fed baby: Lactobacillus acidophilus
      • VAGINA - Lactobacillus
      • STOMACH – none
      • Blood, internal organs – generally sterile
    • How bacteria produce disease
      • 1. Colonization
      • Adherence
        • Pili/ fimbriae
        • Techoic acid
        • Adhesins
        • IgA proteases
      • Avoiding immediate destruction
        • Capsule, etc: anti-phagocytic
          • Streptococcus pyogenes – M protein
          • Neisseria gonorrheae - pili
          • Staphylococcus aureus – protein A
        • IgA protease – Neisseria, Hemophilus, S. pneumoniae
    • How bacteria produce disease
      • 2. Ablity to survive intracellularly
      • M. tuberculosis – inhibiy phagosome-lysosome fusion
      • Listeria – quickly escapes phagosome before fusion
      • Brucella
      • Francisella
      • Legionella
      • 3. Inflammation or Immune-mediated damage
      • Rheumatic fever - cross-reaction of bacteria-induced Ab with tissue antigens
      • Delayed type of hypersensitivity
        • Intracellular bacteria:
          • Mycobacterium tuberculosis, leprae
      • 4. TOXIN Production
    • TOXINS
      • EXOTOXIN ENDOTOXIN
      •  
      • 1. Excreted by living Gram 1. Integral part of the cell
      • positive or negative bacteria wall of Gram negative bacteria
      • 2. Polypeptides complex 2. Lipid A complex (LPS)
      • 3. Heat-labile 3. Heat-stable
      • 4. Highly antigenic 4. Do not stimulate formation of antitoxin
      • 5. Converted to toxoid 5. Not converted to toxoid
      • 6. Highly toxic 6. weakly toxic
      • 7. Nonpyrogenic 7. pyrogenic
      • The criteria that provide proof that a specific bacterium caused a particular disease is
      • A. Koch's postulate C. Danyz phenomenon
      • B. Koch's phenomenon D. none of the above
      • Each of the following statements concerning endotoxins is correct EXCEPT
      • A. They are less potent (ie, less active on a weight basis) than exotoxins
      • B. they are more stable on heating than exotoxins
      • C. they bind to specific cell receptors, whereas exotoxins do not
      • D. they are part of the bacterial cell wall, whereas exotoxins are not
      • The mode of action of oxidizing agents is exemplified by:
      • A. distribution of the cell membrane or wall
      • B. damage to DNA
      • C. protein denaturation
      • D. removal of free sulfhydryl groups
      • Ultraviolet light
      • A. acts as alkylating agent
      • B. disrupts bacterial cell membrane
      • C. removes free sulfhydryl groups
      • D. causes formation of pyrimidine dimers
      • In the culture for voided urine, the colony count considered significant and indicative of infection is
      • A. less than 10,000 colonies/ml
      • B. between 10,000 - 100,000 colonies/ml
      • C. greater than 100,000 colonies/ml
      • D. none of the above
      • MIC in antibiotic susceptibility tests means
      • A. least concentration that kills the test organism
      • B. peak concentration that kills the test organism
      • C. least concentration that inhibits the test organism
      • D. peak concentration that inhibits the test organism
      • E. least concentration that inhibits all organisms
      • Concerning penicillin G
      • A. it has wide antimicrobial spectrum
      • B. it rarely elicits allergic responses
      • C. it is resistant to bacterial beta-lactamase
      • D. it is destroyed by acid in the stomach
      • All of the following statements are true concerning transformation EXCEPT
      • A. A great deal of homology is required between donor and recipient DNA
      • B. Recipient cells must be, competent
      • C. Recipient cells become F+
      • D. DNase can prevent transformation from occurring
      • E. Soluble, double stranded DNA is required
      • All of the following statements are, true concerning transduction EXCEPT:
      • A. Only competent cells can be transduced
      • B. For specialized transduction to occur a prophage is necessary
      • C. New genetic material can be transferred to a bacterium via transduction
      • D. Generalized transduction may occur with lytic phages
      • E. Lysogenic phages are responsible for the virulence of some bacteria
      • All of the following statements concerning an episome (F factor) are true EXCEPT
      • A. Self replicating extra chromosomal DNA
      • B. Codes for sex pili
      • C. Can be incorporated into recipient cell genome
      • D. Codes for common pili
      • E. Required for conjugation
      • Which of these is a known virulence factor?
      • A. Streptococcus pneumoniae capsule
      • B. Escherichia coli flagella
      • C. Sex pili of Salmonella typhi
      • D. Metachromatic granules of Corynebacterium diphtheriae
      • E. Pyocyanin of Pseudomonas aeruginosa
      • Which is found in both Gram-positive and Gram-negative bacteria?
      • A. Endospores
      • B. Endotoxin
      • C. Mesosomes
      • D. Peptidoglycan
      • E. Teichoic acids
      • Which if the following is true regarding the bacterial cell?
      • A. The motility of bacteria is due to flagella, axial filaments or cilia
      • B. The ability to colonize cell surfaces is dependent on toxin production
      • C. The ability to survive in soil for long periods of time is dependent on the production of endospores
      • D. It has the same ribosomes as that of eukaryotic cells
      • Which of the following agents possess either DNA or RNA?
      • Viruses
      • Prions
      • Bacteria
      • Fungi
      • Most pathogenic bacteria grow best at the temperature range of
      • 15-20 o C
      • 30-37 o C
      • 50-60 o C
      • 80-100 o C
      • A newborn was diagnosed with neonatal meningitis. The causative agent was isolated in the vagina of the mother. Which one of the following microorganisms can be a part of the normal vaginal flora of the mother ad can cause neonatal meningitis?
      • Mycoplasma pneumoniae
      • Staphylococcus aureus
      • Escherichia coli
      • Streptococcus agalactiae
      • Almost all parts of the human body are colonized by a diverse group of bacteria that are called normal or indigenous flora. Which of the ff is bacteriologically sterile
      • Fetus intrauterine environment
      • Female urethra
      • GI tract
      • D. vagina
      • All of the following are considered normal microbial flora of the colon EXCEPT
      • A. Bacteroides sp. C. Clostridium sp.
      • B. Fusobacterium sp. D. Vibrio sp
    • GRAM (+) COCCI CATALASE TEST STAPHYLOCOCCUS STREPTOCOCCUS COAGULASE MANNITOL SALT AGAR S. AUREUS Novobiocin S S. EPIDERMIDIS S. SAPROPHYTICUS NOVOBIOCIN S. EPIDERMIDIS Sensitive S. SAPROPHYTICUS Resistant (+) (-)
    • GRAM (+) COCCI CATALASE TEST STAPHYLOCOCCUS STREPTOCOCCUS (+) (-) β -streptococcus S. pyogenes S. agalactiae Bacitracin S CAMP test + Hippurate HOH α -streptococcus S. pneumoniae Viridans Strep Optochin Bile solubility Quellung Animal patho S + + + R - - - γ -streptococcus Enterococcus S. bovis 6.5% NaCl penicillin Grow R No Grow S Gp A Gp B Gp D
      • S. aureus – resistance to penicillin
      • beta lactamase – plasmid
      • altered PBP – chromosomal (e.g., MRSA)
      Normal flora Catalase + Coagulase (-) Novobiocin (R) UTI in newly sexually active females S. saprophyticus Predominant skin flora Catalase (+) Coagulase (-) Novobiocin (S) Catheter and prosthetic devices Endocarditis in i.v. drug abusers Adherence: biofilm S. epidermidis B-lactamase Catalase (+) Coagulase (+) MSA (+) Novobiocin (S) Folliculitis, furuncles, carbuncles, impetigo, cellulitis SSS, TSS, osteomyelitis Food poisoning ProteinA TSST-1 Exfoliatin Enterotoxin S. aureus Impt. Feature Distinguishing characteristic Disease Virulence factor Organism
    • PYR test – pyrrolidonyl arylamidase Normal flora Alpha hemolytic Dental caries Endocarditis Dextran Viridans strep No toxin Vaccine: capsular Alpha hemolytic Optochin (+) Bile solubility (+) Quellung rxn Meningitis (adult) Pneumonia (rusty sputum) Sinusitis Capsule, IgA protease S. pneumoniae (lancet-shaped) Flora colon, URT Alpha, beta or gamma hem., Growth 6.5% NaCl Penicillin R PYR test positive UTI, peritonitis, biliary tract infection, etc E. fecalis (Group D) Vaginal flora, URT Beta hemolytic Catalase (-) CAMP test Hippurate HOH Neonatal sepsis Neonatal meningitis S. agalactiae (Group B) (GBS) No penicillin resistance M12 strain – assoc with AGN Beta hemolytic Catalase (-) Bacitracin (+) PYR test positive ASO Sore throat Scarlet fever Pyoderma Erysipelas Rheumatic fever, AGN M protein Pyrogenic exotoxin S. pyogenes (Group A) (GABS) Impt. Feature Distinguishing characteristic Disease Virulence factor Organism
      • Of the following bacteria, the most frequent cause of prosthetic heart valve infections occurring within two to three months after surgery is
      • A. Streptococcus pneumoniae
      • B. Streptococcus pyogenes
      • C. Staphylococcus aureus
      • D. Staphylococcus epidermidis
      • Three sets of blood cultures were obtained. The aerobic bottle of one set had growth of Staphylococcus epidermidis on the 7-day subculture. This indicates that
      • A. there was low grade bacteremia
      • B. the organism is most likely a contaminant
      • C. the subculture plates were defective
      • D. the subculture should have been done at 5 days
      • A urine Gram stain shows gram-positive cocci in clusters. To SPECIATE this organism from culture, the technician should perform a coagulase test and a(n)
      • A. catalase test
      • B. novobiocin inhibition test
      • C. oxidase test
      • D. B-lactamase test
      • The organism most commonly associated with neonatal purulent meningitis is
      • A. Neisseria meningitidis
      • B. streptococcus pneumoniae
      • C. group B streptococci
      • D. Hemophilus influenzae
      • Isolated from a patient with septicemia is an organism that is Gram-positive, catalase-positive and coagulase-negative. This patient is most likely suffering from
      • A. endocarditis due to Staphylococcus epidermidis
      • B. osteomyelitis due to Staphylococcus aureus
      • C. peritonsillar abscess due to Streptococcus pyogenes
      • D. meningitis due to Streptococcus agalactiae
      • All of the following are characteristic of Staphylococcus aureus EXCEPT
        • Catalase negative
        • Coagulase positive
        • demonstrates beta-hemolysis
        • produces beta-lactamase
      • The CAMP test is done in pregnant women to identify vaginal carriers of
      • Listeria monocytogenes
      • Pasteurella multocida
      • Streptococcus agalactiae
      • Legionella pneumophila
      • A patient with abrupt onset of violent shaking chills a fever of 40.2, pleuritic chest pain/ sputum was productive and rusty colored
      • Adenovirus
      • Streptococcus pneumoniae
      • Pneumocystis carinii
      • Listeria monocytogenes
      • The causative organism of erysipelas
      • Staphylococcus albus
      • Staphylococcus aureus
      • Erysipelothrix insidiosa
      • Streptococcus beta-hemolyticus
      • The virulence factor of group A streptococcus is:
      • A. M protein C. C protein
      • B. Teichoic acid D. T protein
      • Bacitracin disc test identifies
      • A. proteus D. group A streptococcus
      • B. pneumococcus E. staphylococcus aureus
      • C. Neisseria
      • Which of these cultural characteristics is not typical of S. pneumoniae?
      • A. autolysis in bile
      • B. grows in the presence of Optochin
      • C. with types-specific antiserum, capsules swell
      • D. is alpha-hemolytic
      • Many organisms have been shown to be resistant to a variety of antibiotics. Bacteria which may be resistant to the action of penicillin due to the production of beta-lactamase include:
      • A. Corynebacterium diphtheriae
      • B. Nocardia asteroides
      • C. Staphylococcus aureus
      • D. Mycobacterium tuberculosis
      • E. Mycoplasma pneumoniae
      • Food poisoning that produces gastrointestinal symptoms approximately 1 to 2 hours after eating is most likely to be due to
        • Salmonella enteritidis
        • Clostridium perfringens
        • Campylobacter jejuni
        • Staphylococcus aureus
      • Staphylococcus aureus does NOT cause
      • cellulitis C. diarrhea
      • scarlet fever D. impetigo
      • Mainly associated with acute urethritis and cystitis in women
      • S. agalactiae
      • Staph aureus
      • Staph epidermidis
      • D. Staph saprophyticus
      • Staphylococcal scalded-skin syndrome is related to the organism’s ability to produce
      • A. alpha-toxin D. coagulase
      • B. extoliatin E. leukocidin
      • C. Hyaluronidase
      • Common pathogen in surgical implants:
      • A. Klebsiella D. S. pyogenes
      • B. E. coli E. Pseudomonas
      • C. Staph epidermidis
      • Viridian streptococci include all of the following, EXCEPT:
      • S. salivarius C. S. sanguis
      • S. mitis D. S. faecalis
      • Glomerulonephritis is an immunological complication of
      • Staphylcoccal impetigo
      • Pyelonephritis
      • Streptococcal pyoderma
      • Nephron nephrosis
      • Glomerular ischemia
      • A rising titer of anti-streptolysin 0 indicates a diagnosis of
      • erysipelas
      • acute rheuasatic fever
      • glomerulonephritis
      • a recent Streptococcal infection
      • scarlet fever
      • Bacitracin disc test identifies
      • proteus D. group A streptococcus
      • pneumococcus E. Staphylococcus aureus
      • Neisseria
      • The virulence of Streptococcus pneumoniae is a function of its
      • toxin production
      • capsule
      • somatic C-carbohydrate
      • somatic M-protein
      • Which is NOT a correct statement regarding- streptococci?
      • A. Beta (clear)-hemolysis is caused by certain streptococci because they produce enzymes hemolysin that lyse red calls.
      • B. Streptococci are classified primarily by the antigenic differences in their flagella.
      • C. Streptococci are gram-positive cocci that typically form chains.
      • Group A and group B streptococci are in different groups because they have different polysaccharides in their cell wall
      • Substance responsible for adherence of Streptococcus mutans to smooth surface
      • lipoteichoic acid D. dextran
      • lipid A E. peptidoglycan
      • glucan
      • Which will differentiate viridans streptococcus from pneumococci?
      • CAMP test
      • Optochin test
      • Catalase test
      • Bacitracin test
      • A 46-year old female is diagnosed with subacute bacterial endocarditis. It is most commonly caused by organisms known as
      • oral streptococci
      • pyogenic streptococci
      • enterococci
      • pneumococci
      • Sputum culture from a patient with pneumonia revealed beta-hemolytic, catalase-positive cocci. The infecting organism is most probably
      • S. aureus
      • S. epidermidis
      • S. pyogenes
      • S. pneumoniae
      • Gram positive cocci and polymorphonuclear leukocytes are obseved on Gram stain of sputum from a 60-year old alcoholic with pneumonia. Culture of the sputum reveals alpha hemolytic, catalase-negative bacteria. Which one of the following lab tests is the most appropriate next step in the definitive identification of this organism?
      • Bacitracin sensitivity test
      • beta-lactamase production test
      • Elek test
      • Bile solubility test
      • A 23-valent vaccine is used tomprevent disease caused by
      • N. gonorrheae
      • Group B streptococci
      • S. pneumoniae
      • H. influenzae type b
      • The blood culture of a patient with a presumptive diagnosis of endocarditis yields non-hemolytic colonies of Gram positive cocci. The isolate is catalase negative, can grow in 6.5% NaCl and is resistant to penicillin. The isolate is most likely
      • Enterococci
      • Streptococcus agalactiae
      • Streptococcus bovis
      • Streptococcus mutans
      • A 16-year old boy, previously diagnosed with rheumatic heart disease, now presents with fever, weakness and palor. Examination reveals a heart murmur and splenomegaly. History reveals an uneventful tooth extraction 14 days earlier. Which of the following is most likely cause of her present condition?
      • Bacteroides
      • Enterococci
      • Viridans streptococci
      • Pneumococci
      • NEISSERIAE
      • Gram negative diplococci, coffee bean-shaped
      • OXIDASE positive
      • Sensitive to cold, do not refrigerate specimen
      • Chocolate agar – normally sterile specimen
      • Thayer Martin – normally non-sterile specimen
        • V – vancomycin C – colistin N- nystatin
      Pen G, ceftriaxone Vaccine: Strains Y, W-135, C and A; Prophylaxis: rifampin, ciprofloxacin Chocolate agar Thayer Martin Oxidae (+) Glucose (+) Maltose (+) Meningococcemia, Meningitis, Waterhouse- Friedrichsen syndrome Capsule Endotoxin; IgA protease N. meningitidis Ceftriaxone B-lactamase Altered PBP Chocolate agar Thayer Martin Oxidae (+) Glucose (+) Maltose (-) Genital infection Ophthalmia neonatorum Disseminated, septic arthralgia, PID Pili - anti-phagocytic; IgA protease N. gonorrheae Impt. Feature Distinguishing characteristic Disease Virulence factor Organism
      • All of the following statements are true concerning infection with Neisseria meningitidis EXCEPT
      • A. It is the most common cause of meningitis overall
      • B. N. meningitidis is commonly found in the nasopharynx of adult carriers
      • C. The incubation period is usually less than one week
      • D. Penicillin G is the drug of choice of meningococcal infection
      • Which of the following does not contribute to N. gonorrheae of virulence?
      • A. lipopolysaccharide (endotoxin)
      • B. Axial filaments (fibrils)
      • C. IgA protease
      • D. Pili
      • Which is the incorrect statement concerning gonorrhea?
      • A. Infection in men is more frequently symptomatic than in women.
      • B. The definitive diagnosis can be made by detecting at least a 4-fold rise in antibody titer to Neisseria gonorrhea.
      • C. The main host defenses against gonorrhea are antibodies, complement and neutrophils
      • D. A presumptive diagnosis can be made by finding gram-negative kidney-bean shaped diplococci within neutrophils in a urethral discharge.
      • Organisms that may be mistaken for Neisseria gonorrheae in Gram-stained smears of uterine cervix exudates include:
      • A. Lactobacillus species
      • B. Streptococcus agalactiae
      • C. Pseudomonas aeruginosa
      • D. Moraxella osloensis
      • The most common site of asymptomatic gonococcal infection in women is the
      • A. Vagina
      • B. Myometrium
      • C. Urethra
      • D. endocervix
      • CSF from a febrile 25-year old man with possible meningitis is rushed to the laboratory for a stat Gram stain and culture. While performing the Gram stain, the technologist accidentally spills most of the specimen. The smear shows many neutrophils and no microorganisms. Since there is only enough CSF to inoculate one plate, the technologist should use
      • A. blood agar plate
      • B. chopped meat medium
      • C. chocolate agar
      • D. Thayer Martin medium
      • A newborn manifests eye infection; culture reveals the cause to be Neisseria gonorrheae. How did the baby acquire this infections?
      • A. Ascending infection from the mother’s lower genital tract to amniotic fluid at term
      • B. Direct eye inoculation of bacteria from contaminated nursery apparatus
      • C. During spontaneous vaginal delivery, through an infected birth canal
      • D. Transplacentally, from an infected mother’s blood to fetus
      • A case of meningococcal meningitis has been confirmed at a high school in Baguio. A. A. Apart from isolating the patient, what preventive measure should health authorities do?
      • B. Provide rifampin prophylaxis to all close contacts
      • C. Quarantine all close contacts in a special ward in the hospital
      • D. Administer intramuscular penicillin to family an friends
      • All of the above
      • All of the following statements are true concerning infection with Neisseria meningitidis EXCEPT
      • A. It is the most common cause of meningitis overall
      • B. N. meningitidis is commonly found in the nasopharynx of adult carriers
      • C. The incubation period is usually less than one week
      • D. Penicillin G is the drug of choice of meningococcal infection
      • The most common site of asymptomatic gonococcal infection in women is
      • A. Vagina C. urethra
      • B. myocardium D. endocervix
      • The principal habitat of N. meningitidis in carriers is
      • A. meninges C. nasal mucosa
      • B. nasopharynx D. lung
      • A 19-year old college sophomore does 24 hours after the development of fever, petechiae, purpura and disseminated intravascular coagulation. Culture of CSF and blood from the patient on admission to the hospital most likely yielded
      • A. Gram negative, lactose fermenting rods
      • B. Gram negative, oxidase positive diplococci
      • C. Gram positive, catalase negative cocci
      • D. Gram positive, catalase positive cocci
      • CORYNEBACTERIUM
      • Gram positive bacilli, chinese character arrangement
      • Exotoxin
        • lysogenic strains (phage-coded)
        • Subunit A – inhibits protein synthesis by ADP-ribosylation of EF-2
        • Subunit B – binding to receptor
        • TARGET: heart and nerve
      Toxemia No bacteremia Antitoxin Toxoid vaccine Schick test Babes Ernst granules (LAMB) Loffler’s med ELEK TEST Diphtheria Bullneck Pseudomembrane exotoxin C. diphtheriae Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • ELEK TEST – for toxigenicity Filter paper with antitoxin precipitin line Unknown (patient’s isolate) Positive control Negative control
      • Which statement is NOT correct regarding Neisseria gonorrheae?
      • A. It grows poorly on bacteriologic media, so diagnosis is primarily made serologically.
      • B. It produces an IgA protease that degrades secretory IgA thereby enhancing the ability of the organism to colonize the urethral mucosa.
      • C. Resistance to penicillin is mediated both by plasmid-encoded penicillinase and by changes in chromosome-encoded proteins that control the permeability of the drug.
      • D. The antigenicity of its pilus proteins varies significantly, thereby allowing the organisms to evade the immune response.
      • Which is NOT the correct statement regarding C. diphtheriae and the disease diphtheria
      • A. The antigen in the vaccine is diphtheria toxoid
      • B. Diphtheria toxin blocks protein synthesis in human cells by inhibiting elongation factor 2
      • C. The natural habitat of the organism is the soil, where it forms spores
      • D. inhalation of spores is the main mode of transmission
      • E. A gram stain of the exudate from the lesion reveals gram positive rods
      • The test used to determine susceptibility to infection with diphtheria is
      • A. Dick test C. CAMP test
      • B. Schick test D. Mantoux test
      • Concerning diphtheria toxin/ all of the following statements are true EXCEPT
      • A. Its production is mediated by lysogenic strains of bacteria
      • B. Polypeptide A is responsible for inactivating elongation factor-2 of protein synthesis
      • C. Polypeptide B is responsible for the binding and uptake of the diphtheria toxin into the cells.
      • D. Localized necrosis following an injection of diphtheria toxin indicates immunity
      • E. It often causes reversible demyelination of cranial nerves resulting in paralysis of throat muscles
      • All of the following are true concerning Corynebacterium diphtheriae EXCEPT
      • A. Stained organisms have a characteristic ‘chinese-character’ appearance
      • B. The organism may be isolated on Loeffler’s media
      • C. It produces a phage-mediated toxin
      • D. It is part of the normal flora of the oropharynx
      • A 6 year old child of Christian Scientists parents has a sore throat, low grade temperature and malaise. The pharyngeal area is covered with a thick grayish material, not easily dislodged. Throat cultures on tellurite containing medium yield dark grayish black colonies of gram-positive rods which stain metachromatically. The presence of a toxin is demonstrated by the Elek test.
      • A. Bacillus anthracis
      • B. Hemophilus influenzae
      • C. Corynebacterium diphtheriae
      • D. Mycobacterium tuberculosis
      • The presence of immunity to C. diphtheriae is indicate by
      • A. Positive Elek test
      • B. Negative Elek test
      • C. Positive Schick test
      • D. Negative Schick test
      • BACILLUS
      • Gram positive bacilli in chain, ‘bamboo pole-like’
      • aerobic, sporeforming
      • Bacillus anthracis
        • capsule – polypeptide (poly-D-glutamate)
        • toxin - Protective Ag, lethal factor, edema factor
      Fried rice Meat, sauces Emetic type Diarrhea type enterotoxin B. cereus Zoonotic Medusa head cols. Nonhemolytic nonmotile Malignant pustule Woolsorter’s disease GI anthrax Exotoxin capsule B. anthracis Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
      • All of the following are true of Bacillus anthracis EXCEPT
      • A. Primary disease of herbivorous animals
      • B. The organism grew well on most common laboratory media like blood agar plate
      • C. Humans became infected by cutaneous route, inhalation, ingestions and blood transfusion
      • D. The lethal effect of B. anthracis are due to an exotoxin system
      • Vomiting and diarrhea occurs in a patient approximately 8 hours after dining at a Chinese restaurant. The causative agent is most likely
      • A. Bacillus cereus C. S. aureus
      • B. E. coli D. V. parahemolyticus
      • CLOSTRIDIUM
      • Gram positive bacilli
      • Anaerobic, spore-forming
      • tetanus toxin- blocks release of inhibitory transmitter
      • botulinum toxin – blocks release of acetylcholine (lysogeny)
      Metronidazole, vancomycin Toxin in stool R to clindamycin, ceph, amox, amp Pseudomembranous colitis Antibiotic- associated diarrhea Exotoxin A and B C. difficile Toxemia Toxin types A,B,E Clinical dx Botulism Flaccid paralysis exotoxin C. botulinum Toxemia Antitoxin (TIG) Clinical dx Tetanus, lock jaw, Risus sardonicus, opisthotonus Tetanospamin (exotoxin) C. tetani Gaspak jar Chopped meat med Non-motile Anaerobic Nagler rxn Stormy ferm milk Myonecrosis Gastroenteritis Enteritis necroticans Alpha toxin (lecithinase, phospholipase C); enterotoxin C. perfingens Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • MYCOBACTERIUM
      • Acid-fast bacilli
      • Obligate aerobes
      • High lipid content on the cell wall
        • Resistant to:
          • Desiccation
          • Many chemicals
      • Sensitive to UV
      • Slow growing 2-3 wks: positive culture
      • 6-8 wks: negative culture
      • No exotoxins nor endotoxins
    • Mycobacterium tuberculosis complex
      • M. tuberculosis
      • M. bovis
      • M. africanum
    • MOTT – Mycobacterium other than tuberculosis Not transmitted person-to-person Acid-fast Opportunistic in immunocompromised Nonchromogen MAI Not transmitted person-to-person Acid-fast M. kansasii- pulmonary M. marinum-skin infection Photochromogens M. kansasii M. marinum Not transmitted person-to-person Acid-fast Cervical lymphadenitis in children Scotochromogens M. scrofulaceum Not transmitted person-to-person Acid-fasst Fast growers (<days) M. fortuitum Cannot grow in artificial media Acid-fast Tuberculoid leprosy Lepromatous leprosy M. leprae Lowenstein Jensen Middlebrook Serpentine growth No serodiagnosis Acid-fast Obligate aerobe Slow growing Nonpigmented Niacin(+) Catalase (68C) (–) Nitrate red’n + TB Cord factor sulfatides M. tuberculosis Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • Forms of Leprosy Numerous lesions becoming nodular; loss of eyebrows, destruction of nasal septum Paresthesia Leonine facies Fewer lesions: macular, nerve enlargement, paresthesia No. of lesions and other symptoms Large no. of intra. organisms Nerve damage from overgrowth of bacteria in cells Loss of sensation burns and trauma Immune response (CMI killing infected cells) Granuloma formation nerve enlargement/ damage Loss of sensation burns and trauma Damage from High (foam cells totally filled) Low (paucibacillary) No. of org in tissue (-) (+) Lepromin skin test Weak CMI Strong CMI CMI LEPROMATOUS B O R D E R L I N E TUBERCULOID
    • Actinomyces israelli
      • Gram positive bacilli, branching filaments
      • Obligate anaerobe
      • Normal flora: gingival crevices, intestine, vagina
      • Transmission: endogenous
      • Disease: Actinomycosis
        • Cervicofacial (lumpy jaw), thoracic, abdominal, pelvic, CNS
      • ‘ sulfur granules’ in draining sinus tracts
    • MYCOBACTERIA AND CLOSE RELATIVES Rods Yes Yes, obligate Mycobacterium Rods, filaments Partial Yes Nocardia Rods, filaments No No, anaerobic Actinomyces Rods No Yes Corynebacterium Morphology Acid-fast? Aerobic growth? Genus
      • LISTERIA MONOCYTOGENES
      • Gram positive bacilli
      • facultative intracellular parasite
      • tumbling motility in broth; actin jet motility in cells
      • sources: animals, unpasteurized milk products, soft cheeses, deli meats, cabbages (coleslaw)
      • Transmission: foodborne, transplacental, during birth
    • LISTERIA MONOCYTOGENES
      • Diseases:
        • Listeriosis – pregnant women (septicemia)
        • Neonatal disease – granulomatosis infantiseptica
        • IC patients: septicemia and meningitis
        • Listeria meningitis is the most common cause of meningitis in renal transplant patients and adults with cancer
      • The acid-fastness of M. tuberculosis is due to
      • thickness of the cell wall
      • the presence of cord factor
      • mycolic acid
      • absence of outer membrane
      • The pathogenesis of Mycobacterium tuberculosis follows certain norms. Which of the following statements is NOT true
      • A. Dissemination may be by blood stream or erosion of tubercle and spread to contiguous areas
      • B. The primary lesion usually appears in the lungs
      • C. Reactivation is seen primarily in debilitated or immunocompromised patients
      • D. M. tuberculosis produce an exotoxin and contain an endotoxin in its cell wall
      • One of the following is NOT characteristic of TB and its causative agent?
      • acid fast stain
      • absence of pigment
      • C. niacin positive
      • D. susceptible to rifampin
      • E. rapid growth in media
      • The length of culture incubation for isolation of M. tuberculosis before a final negative report is made:
      • A. 1 week C. 8 weeks
      • B. 4 weeks D. 12 weeks
      • Which of the following statements concerning the transmission of Mycobacteria is true
      • A. M. kansasii is transmitted from one AIDS patient to another through respiratory droplets
      • B. M. avium is transmitted human to human
      • C. M. marinum is contracted through skin contact with contaminated water
      • D. M. tuberculosis is not transmitted from one AIDS patient to another
      • A 70-year old woman in a nursing home is treated with a broad spectrum antibiotic for bed sore. Two days later he develops bloody diarrhea. A stool specimen from the patient is positive in an ELISA test for necrotizing cytotoxin, and his treatment is switched to vancomycin. The agent most likely to be responsible for this clinical syndrome is
      • A. Bacteroides fragilis
      • B. Campylobacter jejuni
      • C. Clostridium difficile
      • D. Escherichia coli O157:H7
      • The following are some general characteristics of Mycobacterium leprae EXCEPT
      • A. Human are the natural host of M. leprae
      • B. A cell wall has high lipid content hence its acid fast property
      • C. M. leprae can be grown in lab using either artificial media or cell culture
      • D. Is an acidfast rod
      • Which of the following statements is true about the two major forms of leprosy (tuberculoid and lepromatous)?
      • (A) Tuberculoid leprosy is the hardest to treat due to poor cell-mediated immunity.
      • (B) In either extreme form of leprosy, the lepromin test will be positive.
      • (C) Diagnostic workup on the patient should include a physical examination, skin test, and cultures.
      • (D) Biopsy of lesions from a lepromatous leprosy patient will generally be loaded with M. leprae.
      • (E) Lepromatous leprosy patients usually have few lesions.
      • The length of culture incubation for isolation of M. tuberculosis before a final negative report is made:
      • A. 1 week C. 8 weeks
      • B. 4 weeks D. 12 weeks
      • A 40-year old tropical fish store owner develops a non-healing ulcer on his left arm. He is afebrile and gives no history of night sweats, weight loss, or other constitutional symptoms. Biopsy of the lesion shows granulomatous inflammation and rare acid-fast organism. A tuberculin test is negative. This man most likely has an infection caused by
      • A.Mycobacteria marinum
      • B. Mycobacteria ulcerans
      • C. Mycobacteria tuberculosis
      • D. Mycobacteria kansasii
      • Members of the genus Mycobacterium stain better with the acid-fast stain than with the Gram stain. Which of the following is the BEST explanation for this finding?
      • A. they lack a cell wall; therefore, they cannot absorb the crystal violet
      • B. they have a very thin cell wall that does not retain the crystal violet
      • C. They have a thick polysaccharide capsule that prevents entry of the iodine solution
      • D. they have a large amount of lipid in their cell wall that prevents entry of the crystal violet
      • Diagnosis of tetanus is usually made through
      • A. culture of organism from lesion
      • B. demonstration of antibodies against Clostridium tetani
      • C. clinical manifestation
      • D. demonstration of toxic metabolites
      • Activated macrophages are the effector cells in the expression of a protective, cell-mediated immune response against
      • A. Corynebacterium diphtheriae
      • B. Haemophilus influezae type b
      • C. Listeria monocytogenes
      • D. Streptococcus pneumoniae
      • Listeria monocytogenes infection of an adult is MOST likely to be acquired by
      • A. ingestion of contaminated food
      • B. inhalation of contaminated aerosols
      • C. inosculation with a contaminated needle
      • D. person-to-person contact
      • Bobby was diagnosed with lung cancer and in his bronchial washing acid-fast bacilli were seen mixed with the cancer cells, Bobby had been given the full short course of the TB regimen before and so the doctor suspected a drug resistant strain. The bronchial washing was cultured and it grew orange colored colonies when exposed to light. The most probable etiologic agent is
      • A. Mycobacterium tuberculosis
      • B. Mycobacterium smegmatis
      • C. Mycobacterium kansasii
      • D. Mycobacterium avium complex
      • A definitive identification of Mycobacterium tuberculosis can be obtained by doing the following procedure
      • A. Ziehl Neelsen stain
      • B.AFB culture
      • C. Biopsy of tuberculin test
      • D. Nucleic acid amplification
      • Rifampin, a broad spectrum antimicrobial agent, is effective treatment for tuberculosis by
      • A. Selective inhibition of the biosynthesis of the arabinogalactan and lipo-arabinomanan
      • B. Mediating drug permeability and efflux
      • C. Inhibiting peptidoglycan synthesis by blocking action of D-alanine synthesis
      • D. Binding to RNA polymerase thereby interfering with mRNA synthesis
      • In primary disease, M. tuberculosis survives and grows within these host cells
      • Macrophages
      • Basophils
      • Neutrophils
      • eosinophils
      • Mycobacteria are usually differentiated by the following properties EXCEPT
      • Rate of growth
      • Colonial morphology
      • Pigmentation
      • Acid-fast staining
      • Which is regarded as a TB marker in the diagnosis of tuberculous effusion?
      • Gamma interferon
      • AFB smear
      • Caseation necrosis
      • PPD positivity
      • Mycobacterium tuberculosis is a unique species. Which of the following statements is true about this bacterium?
      • Humans are the natural reservoir of this particular species
      • Its ‘cord factor’ is responsible for its acid-fastness
      • It will grow in the laboratory only under strict anaerobic condition
      • Its virulence is mainly due to the production of mycolic acid
    • GRAM NEGATIVE BACILLI
    • Enterobactericeae
      • Members of the Family  
      • ESCHERICHIA Coliforms
      • KLEBSIELLA (Lactose fermenters – pink colonies)
      • ENTEROBACTER
      • SALMONELLA
      • SHIGELLA Intestinal pathogens
      • YERSINIA
      • PROTEUS PROVIDENCIA
      • MORGANELLA SERRATIA
      • CITROBACTER EDWARDSIELLA
      • CEDECEA KLUYVERA
      Non - Lactose Fermenters (colorless colonies)
    • ENTEROBACTERIACEAE
      • Facultative anaerobes
      • OXIDASE NEGATIVE
      • All ferment glucose
      • Most are motile (peritrichous flagella)
        • Except: Klebsiella, Shigella
      • Media
        • Differential: EMB, McConkey
        • Highly selective: Hektoen enteric agar, SSA, XLD agar
      • Antigens:
        • O – somatic O polysaccharide (LPS)
        • H - flagellar
        • K- envelope or capsular
    • Opportunistic Enterobacteriaceae
      • Normal flora of the colon
      • Immunocompromised
      • Community-acquired or nosocomial
      • Infections outside the intestine
      • Any tissue
      • Common types of infections
        • UTI - meningitis
        • Septicemia - wound infections
        • Pneumonia - various GI disorders
      • Klebsiella pneumoniae
        • Capsule, non-motile, lactose fermenter
        • Pneumonia: ‘currant jelly sputum’
          • Chronic lung disease, alcoholism, diabetes
      • Proteus spp.
        • Urease, phenylalanine deaminase
        • Alkaline urine (staghorn urinary calculi)
        • ‘ Swarming phenomenon’
        • Cross-rxn with Rickettsiae
      • Serratia marcescens
        • 3 enzymes: gelatinase, DNAse, lipase
        • Salmon red pigment
      Opportunistic Enterobacteriaceae
    • ESCHERICHIA COLI
      • Most abundant aerobic flora of the colon
      • Index for fecal pollution of water
      • Major cause of neonatal sepsis & meningitis
      • Most common cause of gram neg infections
      • Causes intestinal and extraintestinal infections
    • Shiga-like toxin – inhibits protein synthesis by binding with 60S ribosomal subunit Persistent diarrhea Childhood diarrhea Fimbriae: ‘stacked brick-like’ biofilm; enterotoxin EAEC O157:H7 Bovine feces hamburger Sorbitol McConkey: NOT ferment SORBITOL Watery diarrhea Hemorrhagic colitis HUS Shiga-like toxin (Stx) (verotoxin) EHEC (VTEC) (STEC) 2 nd to Rotavirus Infantile diarrhea A/E; bundle-forming pili EPEC Watery diarrhea Dysentery (10%) Invasion and destruction of colonic epithelium EIEC Non-invasive Self-limited Toxin immunoassay Travellers’ diarrhea Childhood diarrhea LT – Adenyl cyclase ST- guanylate cyclase ETEC GASTROENTERITIDES/DIARRHEAS septicemia endotoxin E. coli 2 nd to GBS Neonatal sepsis and meningitis K1 capsule endotoxin E. coli Most common cause Lactose fermenter; TSI: A/A + gas; Pink colonies; Greenish metallic sheen UTI P-pili B-hemolysin E. coli Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • SALMONELLA ENTERICA
      • Non-lactose fermenter
      • sensitive to acid
      • Most Salmonella: acquired from animal sources – meat, chicken, milk
      • Serotype typhi : human only
      • 3 clinical entities:
        • Gastroenteritis
        • Septicemia
        • enteric fever (typhoid and paratyphoid fever)
      Infects animals (chicken, turtles, etc) Non-lactose fermenter; TSI- K/A + H2S Gastroenteritis Septicemia Osteomyelitis in sickle cell disease S. typhimurium, enteritidis, etc. No animal reservoir; Sickle cell disease Carrier: gallbladd Blood culture-best Non-lactose fermenter; TSI- K/A + H2S, no gas WIDAL TEST Typhi Dot Typhoid fever Vi Ag, Endotoxin, Intracellular mult S. typhi Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • Shiga toxin – subunit A – inhibits protein synthesis by binding to 60S ribosomal subunit subunit B – binding to receptor 3 activities: neurotoxic, cytotoxic, enterotoxic Infects animals Mimics appendicitis Non-lactose fermenter; TSI- K/A Cold enrichment Bloody diarrhea Enterotoxin Y. enterocolitica Not infect animals No bacteremia Lowest ID50: 100 Non-lactose fermenter; TSI- K/A; No H 2 S Bacillary dysentery: Painful passage (tenesmus) of bloody and mucoid stool Shiga toxin Invasiveness – ulcer at ileum and colon Shigella S. dysenteriae S. sonnei S. flexneri S. boydii Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • Two children were bragging about their intelligence. &quot; When I was eight months old, I could walk,” said one. You call that intelligent?” responded the second child. “When I was that old, I let them carry me.
      • VIBRIOS
      • Gram negative curved bacilli
      • Oxidase +
      • Single polar flagella
      • Grow well in alkaline pH (up to 9)
      • Medium: TCBS (thiosulfate citrate bile salt sucrose agar)
      Seafoods halophilic Gastroenteritis Hemolysin V. parahemolyticus No vertebrate carrier Permanent carrier: rare TCBS agar (yellow colonies) Oxidase (+) Alkaline pH Not halophilic Asiatic cholera Severe dehydration ‘ Rice water stool’ Cholera toxin- adenyl cyclase cAMP V. Cholerae O1 – eltor & cholerae O139- toxin, too Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism R S Polymyxin B + - Voges Proskauer test + - Agglutination of sheep rbc Eltor Classic (cholerae)
      • CAMPYLOBACTER
      • Gram negative curved bacilli (“gull wing’)
      • Oxidase +
      • MICROAEROPHILIC ( CO 2 , O 2 )
      • grow at 42 C
      • Media: Skirrow’s, Butzler’s
      • zoonotic
      Urease (+) Breath Test Biopsy Gastritis, peptic and duodenal ulcer, gastric CA (type 1 carcinogen-WHO) Urease, motility, mucinase invasive H. pylori Infects animals Butzler’s med Skirrow’s med ‘ gull wing-shaped Microaerophilic Thermophilic Bloody diarrhea Enterotoxin C. jejuni Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • X factor only ‘ school of red fish’ Chancroid (soft chancre) Painful genital ulcer Bubo H. ducreyi Chocolate agar Levinthal med X and V factors Satellite phen Pneumonia bronchitis Meningitis Acute epiglottitis Otitis media Capsule (PRP) -type b Endotoxin IgA protease H. influenzae Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism No bacteremia Vaccines: killed org toxoid lymphocytosis Bordet Gengou med; Regan-Lowe med Pertussis, catarrhal paroxysmal (whooping cough) convalescence Capsule Toxin – ADP ribosylation B. pertussis
    • Zoonotic (domestic livestock) Transmitted by fleas Brucella agar Serologic confirmation Undulant fever Acute septicemia Facultative Intracellular parasite Brucella B. abortus B. suis B. melitensis Air conditioning; cooling towers; excavations No human-to-human transmission Dieterle stain, CYE med Opportunistic Immunocomp Legionaire’s dis. (atypical pneumonia) Pontiac fever Facultative intracellular L. pneumophila flea Bubonic plague Septicemic plague Pneumonic plague V and W Ag coagulase Y. pestis Water aerosols, raw vegetables, flowers Resistant to chem. agents, antibiotics; Oxidase + NONFERMENTING Bluish green pigment-pyocyanin Grape-like odor Obligate aerobe Nosocomial infection Burns, Immunocompromised (eg.,cystic fibrosis), ‘ hot tub folliculitis’ Echtyma gangrenosum Exotoxin - (target: liver); Capsule/slime layer P. aeruginosa Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
      • Which of the following is NOT TRUE of E. coli?
        • A. can cause meningitis in neonates
        • B. used as index of fecal contamination of water
        • C. the most frequently isolated gram negative organism from infections
        • d. the most abundant flora of the colon
      • Acute gastroenteritis that occurs 24 hours after a patient attended an outdoor barbeque where the menu consisted of chicken, baked beans and beer is most likely due to
        • A. Salmonella typhi D. Salmonella serotype
        • B. Salmonella typhimurium E. Shigella flexneri
        • C. Staphylococcus aureus
      • What is the virulent factor of E.coli responsible for its causing meningitis in infants?
      • A. enterotoxin C. K Ag
      • B. exotoxin D. Protein
      • Your patient, 40-years old, has had severe diarrhea for the past 2 days, accompanied by fever and a shaking chill. From both the blood culture and the stool culture, a gram-negative rod was isolated that does not ferment lactose. Which one of the following organisms is the MOST likely cause?
      • A. Haemophilus influenza C. Shigella sonnei
      • B. Salmonella enteritidis D. Escherichia coli
      • Which of the following is LEAST associated with enterohemorrhagic E. coli?
      • Fermentation of sorbitol
      • Strain O157:H7
      • Undercooked hamburger
      • Hemolytic uremic syndrome
      • Which of the following is ture about cholera and its causative agent?
      • A secretory diarrheadue to increases in cGMP in the intestinal cells
      • The stool is described as ‘rice water-like’
      • The causative agent is non-motile, nonfermentative
      • Grows poorly in medium with alkaline pH
      • Which of the following is LEAST associated with Helicobacter pylori
      • It requires at least 2% NaCl for growth (halophilic)
      • It requires increased carbon dioxide tension and decreased oxygen tension
      • It is sensitive to the acidity of the gastric juice
      • Most commonly diagnosed by the demonstration of urease production
      • In which type of diarrhea is the use of antibiotics not recommended
      • Salmonellosis
      • Campylobacter infection
      • Cholera
      • Shigellosis
      • Which cause UTI characterized by alkaline urine and formation of urinary calculi?
      • Shigella dysenteriae
      • Escherichia coli
      • Proteus mirabilis
      • Enterobacter cloacae
      • A 2-year old boy presents with fever, headache, stiff neck and signs of meningeal irritation. CSF sent to the laboratory shows Gram negative rods and plenty of PMNs. Cultures on blood agar and McConkey agar are negative., but the chocolate agar incubated in CO2 shows few colonies. Which is the most likely causative organism?
      • Hemophilus influenzae
      • Klebsiella pneumoniae
      • Neisseria meningitidis
      • Streptococcus pneumoniae
      • A 34 year old market vendor presents with explosive watery diarrhea and marked dehydration. The most likely cause is Vibrio cholerae. What is the expected culture characteristic of this organism?
      • Grayish brown matt colonies on chocolate agar
      • Greenish transparent colonies on McConkey agar
      • Mucoid raised opaque colonies on blood agar
      • Yellowish colonies on thiosulfate citrate bile salt sucrose agar
      • Which one of the following bacterial pathogens requires selective culture conditions for reliable isolation from the stool, including media with antibiotics and incubation at 42 o C in increased CO 2 ?
      • Campylobacter jejuni
      • Enterohemorrhagic E. coli
      • Salmonella spp.
      • Shigella spp.
      • Which one of the following is considered facultative intracellular in human macrophages?
      • Enteroinvasive E. coli
      • Enterotoxigenic E. coli
      • Salmonella spp.
      • Shigella spp.
      • A 35-year old male park ranger in rural Arizona arrives to an emergency room with fever and signs and symptoms of septic shock. An enlarged lymph node is discovered under his arm upon P.E. Gram negative coccobacilli that demonstrated bipolar staining were seen in both lymph node aspirate and spinal fluid from the patient. Which of the following is the most likely etiologic agent of this patient’s illness?
      • Brucella abortus
      • Borrelia burgdorferi
      • Chlamydia trachomatis
      • Yersinia pestis
      • A 40-year old male hog farmer complains of intermittent fever, night sweats and headaches to his physician. The patient is hospitalized and blood and bone marrow specimens were collected. The physician requests that the laboratory incubate cultures for at least 6 weeks. Nine days after admission, Gram negative coccobacilli that required CO2 for growth were isolated from the blood and bone marrow. The patient is most likely to be suffering from which one of the following diseases?
      • Brucellosis
      • Bubonic plague
      • Legionaire’s disease
      • Rocky Mountain spotted fever
      • A 20-year old woman comes to your clinic complaining of an irritating vaginal discharge. Upon examination, you find that the cervix and vaginal walls appear normal. The discharge is thin and milky, pH 5.5, and has a fishy odor when treated with potassium hydroxide. You are unable to detect pseudohyphae, buds ot flagellates upon microscopic examination. A Gram stain reveals numerous Gram negative rods, epithelial cells and clue cells, but relatively few Gram positive rods or WBCs. Cervical and vaginal cultures are negative for STDs. What is your diagnosis?
      • Bacterial vaginosis
      • Cervicitis
      • Trichomoniasis
      • Vaginal candidiasis
    • Characteristics of Most Common Types of Vaginitis and Vaginosis 5-6 Above 4.5 Below 4 pH (normal = 3.8-4.2) Tender, red Pink Dry, red Appearance of vaginal mucosa Copious Copious Varies Amount of discharge Frothy Thin. frothy Curdy Consistency of discharge Greenish-yellow Grayish white White Color of discharge Foul Fishy Yeasty or none Odor Protozoa T. vaginalis Bacterium G. vaginalis Fungus C. albicans Agent Trichomoniasis Bacterial Vaginososis Candidiasis
      • A 50-year old doctor complains of recurrent epigastric pain and abdominal fullness. His attending gastroenterologist suspects Helicobacter pylori infection, for which a test can be performed to detect the bacterial production of which enzyme?
      • Catalase
      • Peptidase
      • Oxidase
      • urease
      • A 20-year old woman died after eating hamburger in a fast food restaurant. She had manifested abdominal cramps, vomiting and blood diarrhea. Which of these organisms in the contaminated hamburger was the most likely causative agent?
      • Bacillus cereus
      • Escherichia coli
      • Rotavirus
      • Salmonella typhi
      • The mechanism of action of exotoxin A of Pseudomonas aeruginosa is
      • Activation of acetylcholine esterase
      • Blocking of elongation factor 2 (EF2)
      • Increase cAMP
      • Hydrolysis of lecithin to phosphorylcholine and diacylglycerol
      • This gram negative rod is described to have ‘gull wing’ shape
      • Plesiomonas
      • Aeromonas
      • Campylobacter
      • Vibrio
      • Which specimen should NOT be refrigerated after collection even if processing cannot be done at once?
      • Stool
      • Urine
      • Blood
      • Sputum
      • The most frequently isolated type of H. influenzae in cases of bacterial meningitis in children between 6 months and 2 years is
      • Serotype a
      • Serotype b
      • Serotype c
      • Serotype d
      • One of the following is the appropriate sample for the isolation of Salmonella typhi during the first week of a suspected case of typhoid fever
      • Blood
      • Fecal material
      • Urine’
      • CSF
      • Which of the following organisms is MOST likely to involve invasion of the intestinal mucosa?
      • Vibrio cholerae
      • Shigella sonnei
      • Enteritoxigenic E. coli
      • Clostridium botulinum
      • Which of these organisms is a major pathogen for nosocomial infectios because of its ubiquitous presence in the hospital environment?
      • S. aureus
      • S. epidermidis
      • S. marcescens
      • P. aeruginosa
      • Among the Gram negative tods producing gastroenteritis, the most infectious is
      • V. cholerae
      • E. coli (O157)
      • S. typhimurium
      • S. dysenteriae type 1
      • Which the most infectious stage of pertussis?
      • Catarrhal
      • Prodromal
      • Paroxysmal
      • convalescence
    • SPIROCHETES
      • Gram negative: cannot be seen, very thin
      • Motile, axial filaments
      Ticks (Ixodes) Lyme disease Erythema chronicum migrans B. burdorgferi Human louse ticks Wright’s stain-peripheral blood Relapsing fever B. recurrentis B. hermsii Urine, excreta of rodents Spiral with hook at one or both ends Fletcher’s med Leptospirosis Weil’s disease L. interrogans Not grow in artificial med; Reagin, treponemal Ab Darkfield or IF – 1 o 2 o Sy Serology-2 o & 3 o Sy Syphilis 1 o – hard chancre 2 o – condylomata lata Latent Sy 3 o -gumma Congenital syphilis No toxins T. pallidum Impt. Feature Distinguishing characteristic Disease Impt. Virulence factor Organism
    • A male crab met a female crab and asked her to marry him. She noticed that he was walking straight instead of sideways. Wow, s he thought , this crab is really special. I can’t let him get away. So they got married immediately. The next day she noticed her new husband walking sideways like all the other crabs, and got upset. “What happened?” she asked. “You used to walk straight before we were married. “ Oh, honey,” he replied. “I can’t drink that much everyday.”
      • MYCOPLASMA
      • Smallest free living bacteria
      • No definite shape, not seen in Gram staining
      • PPLO agar
      • require cholesterol for growth
      Cell-wall-less Urease + NGU Can cause urinary calculi U. urealyticum Requires sterol for growth Most common pneumonia in young adults Cell-wall-less ‘ fried egg’ colonies, Cold agglutinins Complement fixation Primary atypical pneumonia walking pneumonia tracheobronchitis P1 protein – attachment Not invasive M. pneumoniae (Eaton Agent) Impt. Feature Distinguishing characteristic Disease Virulence factor Organism
      • CHLAMYDIAE
      • Obligate intracellular parasites (no ATP)
        • Cannot grow in artificialmedia
      • Gram negative, not seen
      • Elementary body – infective form
      • Reticulate body – reproductive form
      • Cell wall lacks muramic acid
      Tetracycline Serologic test respiratory droplets humans Atypical pneumonia C. Pneumoniae TWAR agent erythromycin tetracycline Giemsa stain: inclusion bodies in epithelial cells Immnunofluore-scence Cell culture direct contact, sexual contact, perinatal transmission humans A-B - trachoma, D-K - inclusion conj., NGU, PID, pneumonia, L1-L3 - LGV C. trachomatis tetracycline Serologic test inhalation of dried bird feces birds Psittacosis (pneumonia) C. psittaci Treatment Diagnosis Mode of Transmission in Humans Natural Host Disease Medically Important Species
    • CHLAMYDIA: Developmental Cycle
    • RICKETTSIAE
      • Genera:
        • Rickettsia, Coxiella, Orientia, Ehrlichia
      • Obligate intracellular parasites
      • Gram negative but stain poorly
      • Cross-react with Proteus (OX2, OX19, OXK)
        • WEIL-FELIX TEST
      • Transmitted by arthropods
        • Exception: Coxiella burnetii (Q Fever)
      • Infections: rash, fever
        • Except: Q fever
      • Diseases Etiologic agent Arthropod vector
      • 1. Epidemic typhus fever Rickettsia prowazeki human louse
      • 2. Brill-Zinsser Disease R. prowazeki NONE
      • 3. Endemic typhus R. typhi flea
      • 4. Scrub typhus O. tsutsugamushi mite
      • 5. Rocky Mountain Spotted F. R. rickettsii tick
      • 6. Rickettsialpox R. akari mite
      • 7. Q fever C. burnetii NONE: inhalation
      • 8. Senetsu fever E. senetsu ingestion of raw fish
      • 9. Ehrlichiosis E. chaffeensis tick
      RICKETTSIAE
      • Which of the following statements regarding serodiagnosis of Treponema pallidum disease (syphilis) is correct?
      • (A) The Venereal Disease Research Laboratory (VDRL) test is highly specific and remains positive for life even if the patient is treated with antibiotics.
      • (B) Biologic false-positive results are more common with the microhemagglutination assay for T. pallidum (MHA-TP) than they are with the rapid plasma reagin (RPR) test.
      • (C) Congenital syphilis can be determined at birth by the IgG Fluorescent Treponemal Antibody-Absorption test (FTA-ABS).
      • (D) If early infection or previous infection needs to be documented, the best test is the FTA-ABS test.
      • Which one of the following statements regarding Treponema pallidum is most accurate?
      • A. Despite the therapeutic use of penicillin for many years, no penicillin-resistant strains of T. pallidum have been isolated.
      • B. Specimens cultured on blood agar plates reveal alpha-hemolytic colonies.
      • C. Since the lesions of primary syphilis are primarily due to an immune response against the organism, the lesion typically contains few T. pallidum cells.
      • D. It is a spiral-shaped rod that appears gram-positive in gram stained smear
      • In Weil's disease or acute leptospirosis, the organs most prominently affected by infection are
      • A. pancreas and thyroid
      • B. brain and heart
      • C. lung and heart
      • D. liver and kidneys
      • The resting site for leptospirosis in the natural host is the
      • lumen of the nephrotic tubules
      • liver hepatocytes
      • endothelium
      • eyes
      • Diagnosis of leptospirosis is established in the laboratory by the following methods EXCEPT
      • Demonstration of the organisms by direct darkfield microscopy
      • Serological test
      • Culture
      • Gram stain of infected tissue
      • Lyme disease is an endemic inflammatory disorder with this distinctive skin disorder
      • Chronic dermatitis
      • Erythema marginatum
      • Erythema chronicum migrans
      • Erythema gangrenosum
      • Serology in the diagnosis of syphilis using a non-treponemal test is
      • Microhemagglutination assay
      • Venereal Direase Research Laboratory
      • FTA-Abs test
      • Reiter Protein Complement fixation test
      • The appearance of moist pale papules or colylomas in the anogenital area is characteristic of
      • Primary syphilis
      • Secondary syphilis
      • Tertiary syphilis
      • Latent syphilis
      • Which is the only disease that can be diagnosed by demonstration of spirochetes in peripheral blood smear?
      • Relapsing fever
      • Leptospirosis
      • Pinta
      • Lyme disease
      • The smallest bacteria cultivated on a -cell-free media are
      • A. Rickettsiae
      • B. Chlamydiae
      • C. Mycoplasrna
      • D. Mycobacteria
      • The following statements are true about Chlamydia trachomatis EXCEPT
      • Is has a reservoir in domestic fowls
      • It the most common cause of NGU
      • It can be detected by direct immunofluorescence in specimens
      • Causes infections in newborns
      • Chlamydia and Rickettsiae are correctly described, as
      • A. dividing solely by binary fission
      • B. containing either RNA or DNA but not both
      • C. spread by the bite of an infected arthropod
      • D. resistant to the usual broad-spectrum antibiotics
      • E. obligate parasites of living cells
      • Which of the following statements regarding Rickettsial infections is correct?
      • (A) The rash caused by R. rickettsii generally starts on the ankles or wrists and spreads to the trunk of the body.
      • (B) The rash of Coxiella burnetii starts on the trunk and spreads to the periphery but spares the palms and soles.
      • (C) The rash of R. prowazekii starts on the extremities and spreads to the trunk.
      • (D) R. tsutsugamushi infections have no rash.
      • A 4-yea old Asian child develops an infection with Chlamydia trachomatis. How does infection with this organism cause blindness?
      • Retinal detachment
      • Cataract formation
      • Hemorrhage of the anterior chamber
      • Scarring of the cornea
      • Which of the following is associated with atherosclerosis?
      • K. pneumoniae
      • C. trachomatis
      • S. pyogenes
      • C. pneumoniae
      • Which of the following is the LEAST effective against M. pneumoniae?
      • Erythromycin
      • Tetracycline
      • Kanamycin
      • vancomycin
      • Beta-prophage plays an important role in the toxigenicity of
      • A. Staphylococcus aureus
      • B. Mycobacterium kansasii
      • C. Clostridium tetani
      • D. Corynebacterium diphtheriae
      • E. Vibrio cholera
      • Each of the following microorganisms are responsible for zoonotic infections EXCEPT:
      • A. Campylobacter jejuni
      • B. Shigella sonnet
      • C, Vibrio parahemolyticus
      • D. Pasteurella multocida
      • E. Leptospira interrogans
      • Which of the following is a zoonotic disease?
      • A. Enterotoxigenic 'Escherichia coli
      • B. Enterohemorrhagic Escherichia coli
      • C. Salmonella enteritidis
      • D. Shigella sonnei
      • E. Mycobacterium leprae
      • Regarding Chlamydia trachomatis which statement is NOT true
      • A. Reticulate bodies are able to synthesize their own DNA, RNA and proteins
      • B. Serovars which cause trachoma replicate in epithelial cells of mucosal surfaces
      • C. Serovars which cause lymphogranuloma venereum (LGV) are associated with systemic infection involving lymphoid tissues
      • D. Ocular infections are most frequently treated with tetracycline(s)
      • E. Culture is the major diagnostic tool in most labs
      • All of the following statements are true concerning chlamydia EXCEPT
      • A. Obligate intracellular parasite
      • B. Not seen in Gram Stains of discharge
      • C. TWAR Agent
      • D. Elementary bodies are infectious
      • E. Makes own ATP
    •  
      • Chlamydia resemble bacteria in all of the following ways; EXCEPT:
      • A. they possess both RNA and DNA
      • B. they can be inhibited by many antibiotics effective against bacteria
      • C. they are closely related to gram-positive bacteria
      • D. they multiply by binary fission
      Mycoplasma pneumoniae infection can be diagnosed by both serological findings and culture. Which is the most sensitive and specific of the following serologic methods? A. cold agglutinins C. immunodiffusion B. complement fixation D. Quellung test
      • Gram Negative Enteropathogens:
      • Enterobacteriaceae (E. coli, Salmonella, Shigella, Yersinia)
      • Vibrios
      • Campylobacter
      • Gram Positive Enteropathogens
      • S. aureus
      • B. cereus
      • C. perfringens
      • C. defficile
    • Gastritis Peptic and duodenal ulcer Gastric CA C. jejuni – gastro C. fetus - septicemia V. cholerae- cholera V. Parahemolyticus - Diarrhea (seafds) Disease Skirrow’s med Butzler’s med Skirrow’s med Butzler’s med TCBS Medium (+) (-) (-) Urease (-) (-) (+) Alk. pH thermophilic microaerophilic Oxidase test flagellum Gram stain (-) (+) 42 C (-) (+) (+) (-) (+) (+) (+) Single polar Single polar Single polar Gram (-) curved, S, U-shaped rod Gram (-) ‘gull-wing’ bacillus Gram (-) curved bacillus Helicobacter Campylobacter Vibrio
      • Spore-formers
      • Bacillus
      • Clostridium
      • Coxiella
      No bacteremia diphtheria pertussis shigellosis tetanus botulism cholera
    • Important Bacterial Exotoxins: Inactivates EF-2 by ADP-ribosylation P. aeruginosa Activates adenylclase by ADP-ribosylation B. pertussis Activates adenyl cyclase V. cholerae Shiga-toxin – binds to 60S ribosomal subunit Shiga-like toxin S. dysenteriae Other Shigella spp ETEC – activates adenyl cyclase by ADP-ribos EHEC – shiga-like toxin E. coli Pyrogenic exotoxin – a superantigen S. pyogenes TSST – a superantigen S. aureus 3 toxins; one is an adenyl cyclase B. anthracis Alpha toxin (lecithinase)- damages membrane Enterotoxin - a superantigen C. perfringens Exotoxin B is cytotoxic to enterocytes C. difficile Blocks release of acetylcholine C. botulinum Block release of inhibitory transmitter Glycine C. tetani Inactivates EF-2 by ADP-ribosylation C. diphtheriae
      • Intestinal Pathogens from Animals
      • Salmonella
      • Yersinia
      • Campylobacter
      • V. parahemolyticus
      • REMEMBER!
      • Pathogens primarily within the GI tract
      • (usually no bacteremia)
      • Shigella
      • Vibrio cholerae
      • Vibrio parahaemolyticus
      • Campylobacter jejuni
      • Helicobacter pylori
    • REMEMBER! (most important encapsulated org) S ome K illers H ave P retty N ice C apsule S treptococcus pneumoniae K lebsiella pneumoniae H aemophilus influenzae P seudomonas aeruginosa N eisseria meningitidis C ryptococcus neofromans
    • cAMP (Toxins) C – cholera A – anthrax Σ – E. coli LT P - Pertussis
    • “ Do you think I’ll live another 50 years, Doc?” asked a patient. “ How old are you now?” “ Forty.” “ Do you drink, gamble or chase women?” “ No,” the man answered. “I don’t drink, I never gamble, and I detest women. In fact I don’t have any vices at all.” “ Why then,” the doctor retorted, “do you want to live another 50 years?”
    • IMMUNOLOGY
    • 2 Types of Host Defenses
      • INNATE or Non-specific resistance
        • Defense against any pathogen
        • First line of defense: skin and mucous membranes
        • Second line of defense: phagocytes, inflammation, fever and antimicrobial substances
        • Lysozymes, IFN, complement
        • No memory
    • ADAPTIVE IMMUNITY (Acquired Immunity)
      • Requires prior exposure to the microorganism
      • Specific – produced only against a particular pathogen
      • Function of Lymphocytes (T cells and B cells)
      • Has memory
    • ANTIGENS
      • ANTIGEN (IMMUNOGENS) – any substance that stimulates an immune response and reacts only with the product of response (antibody or T cells)
      • Chemical nature of antigens – proteins, glycoproteins, polysaccharides
      • Requirements for immunogenicity
      • Foreign
      • M.W. = 10,000 or higher
      • Chemically complex
    • DEVELOPMENT OF THE IMMUNE SYSTEM BONEMARROW THYMUS BONEMARROW T CELLS B CELLS PRIMARY LYMPHOID ORGANS Lymph nodes, spleen, tonsils, Peyer’s patches SECONDARY LYMPHOID ORGANS
    • T CELLS B CELLS CELL-MEDIATED IMMUNITY HUMORAL IMMUNITY
      • CD4+ T cells
      • CD8+ T cells
      • Memory T cells
      • B cells ------- plasma cells ---------- antibodies
      • Memory cels
    • CELL-MEDIATED IMMUNITY
      • protection against intracellular organisms like viruses and TB bacilli
      • Protection against tumors
      • Responsible for transplant rejection
      • Types of T Cells
      • CD4+ T cell (helper T cells) – peptide+ MHC class 2
        • TH1 - produce cytokines that activate cells related to CMI:
          • -macrophages
          • -CD8+ T cells
          • -Natural killer cells
      • - Involved inflammation and delayed type of
      • hypersensitivity
      • b. TH2 cells – produce cytokines that
      • help B cells to produce antibodies
      CELL-MEDIATED IMMUNITY
    • Figure 13-2 MHC restriction and antigen presentation to T cells. Left, Antigenic peptides bound to class I MHC molecules are presented to the T-cell receptor (TCR) on CD8 T killer/suppressor cells. Right, Antigenic peptides bound to class II MHC molecules on the antigen-presenting cell (APC) (B cell, dendritic cell, or macrophage) are presented to CD4 helper cells and delayed-type hypersensitivity T cells. Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
      • 2. CD8+ T CELLS
      • Tc cell (cytotoxic T cell) – peptide + MHC class 1
        • Kill target cell on direct contact
        • Important in killing virus-infected cells
      CELL-MEDIATED IMMUNITY
    •  
    • HUMORAL IMMUNITY
      • Antibodies or Immunoglobulins
    • SUMMARY OF IMMUNOGLOBULIN CLASSES Allergic reactions; possibly lysis of parasitic worms Serum function unknown; presence on B cell functions in initiation of immune response Localized protection on mucosal surfaces Esp effective against microorganisms and agglutinating antigens, 1 st Ab produced in initial infection Opsonin (enhances phagocytosis) neutralizes toxins and viruses, protect fetus and newborn Known functions No No No No Yes Placental transfer NO No No yes yes Complement fixation 190,000 175,000 405,000 970,000 150,000 Mol Wt Bound to mast cells and basophil throughout body, blood B cell surface, blood lymph Secretions (tears, saliva, mucus, intestine, milk) blood, lymph Blood, Lymph, B cell surface Blood, lymph, intestine Location 0.002% 0.2% 10-15% 5-10% 80% % total serum Ab monomer monomer Dimer Pentamer monomer Structure IgE IgD IgA IgM IgG CHARACTERISTICS
    •  
    • Figure 12-8 The classical, lectin, and alternate complement pathways. Despite different activators, the goal of these pathways is cleavage of C3 and C5 to provide chemoattractants and anaphylotoxins (C3a, C5a), an opsonin (C3b) that adheres to membranes, and to initiate the membrane attack complex to kill cells. MASP, MBP-associated serine protease; MBP, mannose-binding protein. (Redrawn from Rosenthal KS, Tan JS: Rapid review microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
    • Figure 12-8 The classical, lectin, and alternate complement pathways. Despite different activators, the goal of these pathways is cleavage of C3 and C5 to provide chemoattractants and anaphylotoxins (C3a, C5a), an opsonin (C3b) that adheres to membranes, and to initiate the membrane attack complex to kill cells. MASP, MBP-associated serine protease; MBP, mannose-binding protein. (Redrawn from Rosenthal KS, Tan JS: Rapid review microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
    • Figure 12-8 The classical, lectin, and alternate complement pathways. Despite different activators, the goal of these pathways is cleavage of C3 and C5 to provide chemoattractants and anaphylotoxins (C3a, C5a), an opsonin (C3b) that adheres to membranes, and to initiate the membrane attack complex to kill cells. MASP, MBP-associated serine protease; MBP, mannose-binding protein. (Redrawn from Rosenthal KS, Tan JS: Rapid review microbiology and immunology, St. Louis, 2002, Mosby.) Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
    • Biologic Activities of Complement
      • Cytolysis - MAC
      • Opsonization – C3b
      • Chemotaxis – C5a
      • Anaphylatoxin –C5a, C3a
        • Increased vascular permeability
        • Smooth muscle contraction
        • Degranulation of mast cells
    • HYPERSENSITIVITY Tuberculin rxn, TB, leprosy, contact dermatitis TH1-Ag complex----> lymphokine release ---> activated macrophage---> tissue injury. CD8+ Tcell cytotoxicity TH1(CD4+), lymphokines, CD8+ Tcell IV. Delayed Type Arthus rxn; Farmer’s lung; Serum sickness; AGN; rheumatoid arthritis Soluble Ag-Ab complex: Platelet aggregation Release of anaphylatoxin, chemotactic factors (for neutrophils) IgG or IgM, Complement III. Immune Complex type Transfusion reaction, HDN, hemolytic anemia, Good Pasture’s syndrome, Myathenia gravis Cellular Ag-Ab complex; Complement activated; Cytolysis ADCC Opsonization IgG or IgM, Complement, K cell II. Cytotoxic Type Urticaria Asthma Food allergy Penicillin allergy Atopic dermatitis Bee sting Allergen crosslinks IgE Attached to mast cell; Degranulation, release of histamine and other vasoactive amines IgE Mast cells vasoactive amines I. Anaphylactic type Example Mechanism Primary Mediators Type
    • Figure 14-11 Type I hypersensitivity: immunoglobulin E (IgE)- mediated atopic and anaphylactic reactions. IgE produced in response to the initial challenge binds to Fc receptors on mast cells and basophils. Allergen binding to the cell surface IgE promotes the release of histamine and prostaglandins from granules to produce symptoms. Examples are hay fever, asthma, penicillin allergy, and reaction to bee stings. IL, Interleukin. Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
    •  
    • Figure 14-12 Type II hypersensitivity: mediated by antibody and complement. Complement activation promotes direct cell damage through the complement cascade and by the activation of effector cells. Examples are Goodpasture's syndrome, the response to Rh factor in newborns, and autoimmune endocrinopathies. ADCC, Antibody-dependent cellular cytotoxicity; Ig, immunoglobulin. Downloaded from: StudentConsult (on 23 September 2006 05:04 AM) © 2005 Elsevier
    •  
      • Questions 1-6
      • (A) T cells
      • (B) B cells
      • (C) Macrophages
      • (D) B cells and macrophages
      • (E) T cells, B cells, and macrophages
      • Major source of interleukin-1
      • Acted on by interleukin-1
      • Major source of interleukin-2
      • Express class I MHC markers
      • Express class II MHC markers
      • Express surface immunoglobulin
      • (A) Class I MHC proteins
      • (B) Class II MHC proteins
      • 1. Involved in the presentation of antigen to CD4-positive cells
      • 2. Involved in the presentation of antigen to CD8-positive cells
      • 3. Involved in antibody responses to T-dependent antigens
      • 4. Involved in target cell recognition by cytotoxic T cells
      • Which are both opsonins?
      • A. IgG and IgA D. IgA and C3a
      • B. C3b andC3a E. IgA and C3b
      • C. IgG and C3b
      • The rapid rise , elevated level and prolonged production of antibody that follows second exposure to antigen is known as
      • A. Delayed hypersensitivity reaction
      • B. Anamnestic response
      • C. Autoimmune reaction
      • D. Thymus-independent response
      • C3 is cleaved to form C3a and C3b by C3 convertase. C3b is involved in all of the following EXCEPT:
        • A. altering vascular permeability
        • B. promoting phagocytosis
        • C. forming alternative-pathway C3 convertase
      • D. forming C5 convertase
      • You have a patient who makes autoantibodies against his own red blood cells, leading to hemolysis. Which one of the following mechanisms is MOST likely to explain the hemolysis?
      • A. Perforins from cytotoxic T cells lyse the red cells
      • B. Neutrophils release proteases that lyse the red cells
      • C. Interleukin-2 binds to its receptor on the red cells, which results in lysis of the red cells
      • D. Complement is activated, and membrane attack complexes lyse the red cells
      • Your patient became ill 10 days ago with a viral disease. Laboratory examination reveals that the patient's antibodies against this virus have a high ratio of IgM to IgG. What is your conclusion?
        • A. It is unlikely that the patient has encountered this organism previously
        • B. The patient is predisposed to IgE-mediated hypersensitivity reactions
        • C. The information given is irrelevant to previous antigen exposure
        • D. It is likely that the patient has an autoimmune disease