46-1

Microbiology
Class II

Dr. Ashish Jawarkar
Consultant Pathologist
Parul Sevashram hospital
© 2009 The McGraw-Hill Co...
46-2

Microbiology and the Role of the
Medical Assistant


Microbiology – study of microorganisms
(simple forms of life v...
46-3

Microbiology and the Role of the
Medical Assistant (cont.)


Medical assistant


Assists physician



Obtains spe...
46-4

How Microorganisms Cause Disease


Cause disease in variety of ways







Use nutrients needed by cells and t...
46-5

How Microorganisms Cause
Disease (cont.)


Localized symptoms







Swelling
Pain
Warmth
Redness

Generalized...
46-6

Apply Your Knowledge
1. What role does the medical assistant play in relation to

microbiology?
ANSWER: The medical ...
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 ...
46-9





Protozoans – single celled eukaryotes
Fungi – multicelled eukaryotes with cell wall
Parasites – multicelled e...
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
Exampl...
46-12

Apply Your Knowledge
Describe the classifications of microorganisms and give
an example of each.
ANSWER: Microorgan...
46-13

Viruses



Smallest known
infectious agents
Subcellular
microorganism




Have only nucleic acid
surrounded by ...
46-14

Viruses (cont.)


Illnesses caused by viruses








Colds
Influenza
Croup
Hepatitis
Warts







AIDS...
46-15

Bacteria




Single-celled prokaryotic organisms
Reproduce rapidly
Classification




Shape
Ability to retain...
46-16

Bacteria: Classification and
Identification


Shape


Coccus – spherical, round, or ovoid



Bacillus – rod-shap...
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 +v...
46-19

Bacteria: Classification and
Identification (cont.)


Special groups






Mycobacteria – bacilli
with a cell w...
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

...
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



Superficia...
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 w...
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

___ Class...
46-30

How Infections Are Diagnosed


Steps to diagnosis and treatment
1.

Examine the patient



2.

Presumptive diagn...
46-31

How Infections Are Diagnosed (cont.)
3.

Examine specimen directly



4.

Wet mount
Smear

Culture specimen



...
46-32

How Infections Are Diagnosed (cont.)
5.

Determine sensitivity to
antibiotics

6.

Treat the patient as
ordered


...
46-33

Apply Your Knowledge
What is the process for diagnosing an infection?
ANSWER: There are six steps for diagnosis and...
46-34

Specimen Collection


Must be collected correctly


If not, may not grow in
culture



Contaminants may be
mista...
46-35

Specimen Collection (cont.)


Devices






Use appropriate collection
device or specimen container
Sterile swa...
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
co...
46-38

Specimen Collection (cont.)


Throat culture specimens






Swab back of throat in the area
of the tonsils
Avo...
46-39

Specimen Collection (cont.)


Urine specimen




Clean-catch
midstream to
minimize
contaminants
Process within 6...
46-40

Specimen Collection (cont.)


Wound specimen




Swab wound or
lesion
Do not touch
outside of wound



Stool Sp...
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 har...
46-43

Transporting Specimens to an
Outside Laboratory


Many offices send cultures to an outside lab



Three main obje...
46-44

Direct Examination of Specimens


Enables physician to initiate treatment immediately



Wet mounts



NaCl mix...
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
i...
46-47

Apply Your Knowledge
1. What are the methods for preparing a slide for direct

examination by the physician?
ANSWER...
46-48

Culturing Specimens


Inoculating a culture plate







Transfer some of the specimen onto a culture
plate
La...
46-49

Culturing Specimens (cont.)


Incubating culture plates





35 to 37º C for 24 to 78 hours
Agar side up

Inter...
46-50

Culturing Specimens (cont.)


Culture media







Liquid, semisolid, or
solid forms
Contains agar
Selective o...
46-51

Apply Your Knowledge
3. What is the process for culturing a specimen?

ANSWER: The culture medium is inoculated wit...
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 – littl...
46-54

Apply Your Knowledge
1. What is the difference between selective and

nonselective culture media?
ANSWER: Selective...
46-55

In summary







Types of microorganisms
Nomenclature
Structure
Specimen collection
Techniques
Antibiotic re...
46-56

Thank You

© 2009 The McGraw-Hill Companies, Inc. All rights reserved
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This is a series of lectures on microbiology useful for undergraduate medical and paramedical students

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microbiology introduction 2

  1. 1. 46-1 Microbiology Class II Dr. Ashish Jawarkar Consultant Pathologist Parul Sevashram hospital © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  2. 2. 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
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. 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
  7. 7. 46-7 Classification of Microorganisms  Structure © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  8. 8. 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
  9. 9. 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
  10. 10. 46-10 Naming of microorganisms © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. 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
  17. 17. 46-17 Bacteria: Classification and Identification  Shape © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  18. 18. 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
  19. 19. 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
  20. 20. 46-20 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  21. 21. 46-21 Protozoans © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  22. 22. 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
  23. 23. 46-23 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  24. 24. 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
  25. 25. 46-25 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  26. 26. 46-26 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  27. 27. 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
  28. 28. 46-28 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  29. 29. 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
  30. 30. 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
  31. 31. 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
  32. 32. 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
  33. 33. 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
  34. 34. 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
  35. 35. 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
  36. 36. 46-36 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  37. 37. 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
  38. 38. 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
  39. 39. 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
  40. 40. 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
  41. 41. 46-41 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  42. 42. 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
  43. 43. 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
  44. 44. 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
  45. 45. 46-45 © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  46. 46. 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
  47. 47. 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
  48. 48. 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
  49. 49. 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
  50. 50. 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
  51. 51. 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
  52. 52. 46-52 Determining Antimicrobial Sensitivity © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  53. 53. 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
  54. 54. 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
  55. 55. 46-55 In summary       Types of microorganisms Nomenclature Structure Specimen collection Techniques Antibiotic resistance © 2009 The McGraw-Hill Companies, Inc. All rights reserved
  56. 56. 46-56 Thank You © 2009 The McGraw-Hill Companies, Inc. All rights reserved
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