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This is a series of lectures on microbiology useful for undergraduate medical and paramedical students

This is a series of lectures on microbiology useful for undergraduate medical and paramedical students

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    microbiology introduction 2 microbiology introduction 2 Presentation Transcript

    • 46-1 Microbiology Class II Dr. Ashish Jawarkar Consultant Pathologist Parul Sevashram hospital © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-2 Microbiology and the Role of the Medical Assistant  Microbiology – study of microorganisms (simple forms of life visible only with a microscope) © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-3 Microbiology and the Role of the Medical Assistant (cont.)  Medical assistant  Assists physician  Obtains specimens  Prepares specimens for direct examination  Prepares specimens for transportation to reference laboratory  If office has a POL, performs microbiologic procedures © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-4 How Microorganisms Cause Disease  Cause disease in variety of ways      Use nutrients needed by cells and tissues Damage cells directly Produce toxins May remain localized or become systemic Transmission   Direct contact Indirect contact © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-5 How Microorganisms Cause Disease (cont.)  Localized symptoms      Swelling Pain Warmth Redness Generalized symptoms      Fever Tiredness Aches Weakness Normal flora   Provides a barrier Can cause an infection © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-6 Apply Your Knowledge 1. What role does the medical assistant play in relation to microbiology? ANSWER: The medical assistant may assist the physician in obtaining specimens, obtain specimens herself, prepare specimens for direct examination or transport to a reference laboratory, and possibly perform microbiologic procedures. 2. How do microorganisms cause disease? ANSWER: Organisms cause disease by using nutrients needed by cells and tissues, damaging cells directly, or producing toxins. © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-7 Classification of Microorganisms  Structure © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-8 Classification of Microorganisms  Classification by structure  Subcellular – DNA or RNA surrounded by a protein coat – viruses  Prokaryotic – simple cell structure with no nucleus or organelles – bacteria  Eukaryotic – complex cell structure with nucleus and specialized organelles – protozoans, fungi, parasites © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-9    Protozoans – single celled eukaryotes Fungi – multicelled eukaryotes with cell wall Parasites – multicelled eukaryotes without cell wall © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-10 Naming of microorganisms © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-11 Naming of Microorganisms (cont.)  Standardized naming  Genus    Category of biologic classification Example – Staphylococcus Species of organism   Represents a distinct type of microorganisms Examples – Staphylococcus aureus and Staphylococcus epidermidis © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-12 Apply Your Knowledge Describe the classifications of microorganisms and give an example of each. ANSWER: Microorganisms are classified as: Subcellular organisms that have DNA or RNA surrounded by a protein coat – viruses Prokaryotic organisms have a simple cell structure with no nucleus or organelles – bacteria Eukaryotic have a complex cell structure with nucleus and specialized organelles – protozoans, fungi, parasites © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-13 Viruses   Smallest known infectious agents Subcellular microorganism   Have only nucleic acid surrounded by a protein coat Must live and grow in living cells of other organisms Hepatitis virus © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-14 Viruses (cont.)  Illnesses caused by viruses       Colds Influenza Croup Hepatitis Warts      AIDS Mumps Rubella Measles Herpes Vaccines are available for many viruses © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-15 Bacteria    Single-celled prokaryotic organisms Reproduce rapidly Classification    Shape Ability to retain dyes Ability to grow with / without air Bacillus bacterial classification © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-16 Bacteria: Classification and Identification  Shape  Coccus – spherical, round, or ovoid  Bacillus – rod-shaped  Spirillum – spiral-shaped  Virbrio – comma-shaped Spirillum bacterial classification © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-17 Bacteria: Classification and Identification  Shape © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-18 Bacteria: Classification and Identification (cont.)  Ability to retain certain dyes    Gram’s stain (Gram +ve, Gram –ve) Acid-fast stain (AFB+ve, AFB –ve) Ability to grow in presence or absence of air   Aerobes – grow best in the presence of oxygen Anaerobes – grow best in the absence of oxygen © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-19 Bacteria: Classification and Identification (cont.)  Special groups    Mycobacteria – bacilli with a cell wall that differs from most bacteria   Rickettsiae   Very small Live and grow within other living organisms such as mites and ticks Chlamydiae  Cell wall structure differs from other bacteria Live and grow within other living cells Mycoplasmas – completely lack the rigid cell wall © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-20 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-21 Protozoans © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-22 Protozoans  Single-celled eukaryotic organisms, larger than bacteria  Found in soil and water  Illnesses     Malaria Amebic dysentery Trichomoniasis vaginitis Leading cause of death in developing countries © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-23 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-24 Fungi   Eukaryotic organisms with rigid cell wall Yeasts   Single-celled Reproduce by budding  Superficial infections     Molds   Large, fuzzy, multicelled organisms Produce spores  Athlete’s foot Ringworm Thrush Can cause systemic infections © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-25 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-26 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-27 Multicellular Parasites  Organisms that live on or in another organism and use it for nourishment  Parasitic worms     Usually due to poor sanitation Roundworms Flatworms Tapeworms  Parasitic insects      Bite or burrow under the skin Mosquitoes Ticks Lice mites © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-28 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-29 Apply Your Knowledge Matching: ANSWER: ___ Yeast or mold D A. Virus ___ Tapeworm / lice E B. Bacteria ___ Classified by shape B C. Protozoan A ___ Subcellular organism D. Fungus B ___ May be aerobic or anaerobic E. Multicellular parasite Very Good! A ___ Smallest known organism C ___ Found in soil and water © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-30 How Infections Are Diagnosed  Steps to diagnosis and treatment 1. Examine the patient   2. Presumptive diagnosis May or may not need additional tests Obtain specimen(s)   Label properly Include presumptive diagnosis © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-31 How Infections Are Diagnosed (cont.) 3. Examine specimen directly   4. Wet mount Smear Culture specimen   Culture medium – contains nutrients Examine culture visually and microscopically © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-32 How Infections Are Diagnosed (cont.) 5. Determine sensitivity to antibiotics 6. Treat the patient as ordered  Antimicrobial – to kill pathogen or suppress its growth © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-33 Apply Your Knowledge What is the process for diagnosing an infection? ANSWER: There are six steps for diagnosis and treatment of an infection: 1. Examine the patient 4. Culture the specimen 2. Obtain specimen(s) 5. Determine sensitivity 3. Examine specimen directly 6. Treat patient / appropriate antimicrobial Super! © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-34 Specimen Collection  Must be collected correctly  If not, may not grow in culture  Contaminants may be mistakenly identified  Patient may receive incorrect or harmful therapy © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-35 Specimen Collection (cont.)  Devices    Use appropriate collection device or specimen container Sterile swabs – absorbent material on the tip Collection and transporting systems    Sterile, self-contained Transport medium Aerobic or anaerobic © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-36 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-37 Specimen Collection: Guidelines  Avoid causing harm, discomfort, or undue embarrassment  Obtain specimen at correct time  Obtain sufficient quantity of specimen  Obtain specimen prior to the start of antimicrobial therapy  Label correctly Collect from appropriate site   Use appropriate devices © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-38 Specimen Collection (cont.)  Throat culture specimens    Swab back of throat in the area of the tonsils Avoid touching any structures in the mouth Prepare culture plate or prepare correctly for transport to laboratory © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-39 Specimen Collection (cont.)  Urine specimen   Clean-catch midstream to minimize contaminants Process within 60 minutes or refrigerate  Sputum specimen   Specimen from lungs Avoid contaminating specimen with saliva © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-40 Specimen Collection (cont.)  Wound specimen   Swab wound or lesion Do not touch outside of wound  Stool Specimens  Technique varies    Bacterial infection Protozoal or parasitic infection Instruct patient in correct collection procedure © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-41 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-42 Apply Your Knowledge What are the general guidelines for specimen collection? ANSWER: They are to avoid causing harm, discomfort, or undue embarrassment; collect from appropriate site; obtain specimen at correct time; use appropriate collection devices; obtain sufficient quantity of specimen; obtain specimen prior to the start of antimicrobial therapy; and label specimen correctly. © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-43 Transporting Specimens to an Outside Laboratory  Many offices send cultures to an outside lab  Three main objectives    Follow proper collection procedures and proper collection device Prevent deterioration of specimen Protect anyone handling specimen © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-44 Direct Examination of Specimens  Enables physician to initiate treatment immediately  Wet mounts   NaCl mixed with specimen of glass slide Presence of pathogen and movement of microorganism  Potassium hydroxide (KOH) mounts   Used if a fungal infection of the skin, nails, or hair is suspected KOH dissolves keratin that can mask presence of a fungus © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-45 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-46 Preparation and Examination of Stained Specimens   Quick, tentative diagnosis Differentiation between types of infections  Gram’s stain   Moderatecomplexity test Bacteria either retain or lose purple color   Gram-positive bacteria Gram-negative bacteria © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-47 Apply Your Knowledge 1. What are the methods for preparing a slide for direct examination by the physician? ANSWER: They are wet mount and KOH mount. 2. How does the examination of stained specimens facilitate patient care? ANSWER: Stained specimens enable the physician to provide a quick, tentative diagnosis and differentiate between types of infections. © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-48 Culturing Specimens  Inoculating a culture plate     Transfer some of the specimen onto a culture plate Label the plate correctly Qualitative analysis – determination of type of pathogen Quantitative analysis – number of bacteria present in sample © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-49 Culturing Specimens (cont.)  Incubating culture plates    35 to 37º C for 24 to 78 hours Agar side up Interpreting cultures     Requires skill and practice Characteristics of colonies Relative number Changes to media around colonies © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-50 Culturing Specimens (cont.)  Culture media     Liquid, semisolid, or solid forms Contains agar Selective or nonselective Special culture units   Rapid urine culture – Uricult Also available for throat, vaginal, and blood specimens © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-51 Apply Your Knowledge 3. What is the process for culturing a specimen? ANSWER: The culture medium is inoculated with the specimen and placed in an incubator to promote growth of the organism on the culture medium. © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-52 Determining Antimicrobial Sensitivity © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-53 Determining Antimicrobial Sensitivity  An outside lab reports    Sensitive – no growth Intermediate – little growth Resistant – overgrown  Procedure    Filter paper containing antimicrobial agents placed on inoculated agar plate Incubated for 24 hours Evaluate effectiveness of agent © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-54 Apply Your Knowledge 1. What is the difference between selective and nonselective culture media? ANSWER: Selective culture media allows the growth of only certain kinds of bacteria. Unselective culture media support the growth of most organisms. 2. The office received a culture sensitivity report on a bacteria that said it was resistant to an antimicrobial. What does this mean? ANSWER: It means that the bacteria was not killed by the antimicrobial and that there was an overgrowth of the bacteria. © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-55 In summary       Types of microorganisms Nomenclature Structure Specimen collection Techniques Antibiotic resistance © 2009 The McGraw-Hill Companies, Inc. All rights reserved
    • 46-56 Thank You © 2009 The McGraw-Hill Companies, Inc. All rights reserved