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
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
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
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?
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
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
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?
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
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?
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 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
Gram positive bacilli, chinese character arrangement
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
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.
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
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
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 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
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
Most Salmonella: acquired from animal sources – meat, chicken, milk
Serotype typhi : human only
3 clinical entities:
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. " 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.
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
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 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?
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 ?
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?
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?
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?
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?
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?
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.”
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
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
Enterobacteriaceae (E. coli, Salmonella, Shigella, Yersinia)
Gram Positive Enteropathogens
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
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
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?”
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