1. Chapter 46 Introduction to Microbiology Medical Assisting
PowerPoint® presentation to accompany:
Medical Assisting
Third Edition
Booth, Whicker, Wyman, Pugh, Thompson

2. Learning Outcomes 46.1 Define microbiology.
46.2 Describe how microorganisms cause disease.
46.3 Describe how microorganisms are classified and named.
46.4 Explain how viruses, bacteria, protozoans, fungi, and parasites differ and give examples of each.

3. Learning Outcomes (cont.)
46.5 Describe the process involved in diagnosing an infection.
46.6 List general guidelines for obtaining specimens.
46.7 Describe how throat culture, urine, sputum, wound, and stool specimens are obtained.
46.8 Explain how to transport specimens to outside laboratories.

4. Learning Outcomes (cont.)
Describe two techniques used in the direct examination of culture specimens.
46.10 Explain how to prepare and examine stained specimens.
46.11 Describe how to culture specimens in the medical office.

5. Learning Outcomes (cont.)
46.12 Explain how cultures are interpreted.
46.13 Describe how to perform an antimicrobial sensitivity determination.
46.14 Explain how to implement quality control measures in the microbiology laboratory.

6. Introduction Microorganisms cause disease or infection
Pathogenic in nature
Displaced from their natural environment
Medical assistant
Identification of microorganisms
Proper collection techniques
Testing procedures
Quality control

7. Microbiology and the Role of the Medical Assistant
Microbiology – study of microorganisms (simple forms of life visible only with a microscope)
Microorganisms
Normal flora
Pathogenic

8. Microbiology and the Role of the Medical Assistant (cont.)
Assists physician
Obtains specimens
Prepares specimens for direct examination
Prepares specimens for transportation to reference laboratory
If office has a POL, performs microbiologic procedures

9. 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

10. 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

11. Apply Your Knowledge Yippee! 2 for 2
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.
How do microorganisms cause disease?
Yippee!
2 for 2
ANSWER: Organisms cause disease by using nutrients needed by cells and tissues, damaging cells directly, or producing toxins.

12. Classification and Naming 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

13. Classification and 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

14. Apply Your Knowledge Correct!
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
Correct!

15. 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

16. Viruses (cont.) Illnesses caused by viruses
Colds
Influenza
Croup
Hepatitis
Warts
Vaccines are available for many viruses
AIDS
Mumps
Rubella
Measles
Herpes

17. Bacillus bacterial classification
Single-celled prokaryotic organisms
Reproduce rapidly
Classification
Shape
Ability to retain dyes
Ability to grow with / without air
Biochemical reactions
Bacillus bacterial classification

18. Bacteria: Classification and Identification
Shape
Coccus – spherical, round, or ovoid
Bacillus – rod-shaped
Spirillum – spiral-shaped
Virbrio – comma-shaped
Spirillum bacterial classification

19. Bacteria: Classification and Identification (cont.)
Ability to retain certain dyes
Gram’s stain
Acid-fast stain
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
Biochemical reactions

20. 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

21. Protozoan Trichomonas vaginalis
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
Protozoan Trichomonas vaginalis

22. Yeast: a single-celled fungi
Eukaryotic organisms with rigid cell wall
Yeasts
Single-celled
Reproduce by budding
Molds
Large, fuzzy, multicelled organisms
Produce spores
Superficial infections
Athlete’s foot
Ringworm
Thrush
Can cause systemic infections

23. 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

24. Very Good! Apply Your Knowledge ANSWER: Matching:
___ Yeast or mold A. Virus
___ Tapeworm / lice B. Bacteria
___ Classified by shape C. Protozoan
___ Subcellular organism D. Fungus
___ May be aerobic or anaerobic E. Multicellular parasite
___ Smallest known organism
___ Found in soil and water
Very Good! E B A B A C

25. How Infections Are Diagnosed
Steps to diagnosis and treatment
Examine the patient
Presumptive diagnosis
May or may not need additional tests
Obtain specimen(s)
Label properly
Include presumptive diagnosis

26. How Infections Are Diagnosed (cont.)
Examine specimen directly
Wet mount
Smear
Culture specimen
Culture medium – contains nutrients
Examine culture visually and microscopically

27. How Infections Are Diagnosed (cont.)
Determine sensitivity to antibiotics
Treat the patient as ordered
Antimicrobial – to kill pathogen or suppress its growth

28. Super! Apply Your Knowledge
What is the process for diagnosing an infection?
ANSWER: There are six steps for diagnosis and treatment of an infection:
Examine the patient 4. Culture the specimen
Obtain specimen(s) 5. Determine sensitivity
Examine specimen directly 6. Treat patient / appropriate antimicrobial
Super!

29. 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

30. 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

31. Specimen Collection: Guidelines
Avoid causing harm, discomfort, or undue embarrassment
Collect from appropriate site
Obtain specimen at correct time
Use appropriate devices
Obtain sufficient quantity of specimen
Obtain specimen prior to the start of antimicrobial therapy
Label correctly

32. 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

33. 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

34. 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

35. Apply Your Knowledge Fantastic!
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.
Fantastic!

36. 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

37. Transporting Specimens to an Outside Laboratory (cont.)
Regularly scheduled daily pickups by the lab
Most reliable
As-needed pickup by the lab
Through the mail
Follow U.S. Public Health Service regulations
Etiologic Agent label

38. Impressive! Apply Your Knowledge
What are the objectives for transporting a specimen to an outside laboratory?
ANSWER: They are to follow proper collection procedures and use proper collection device, prevent deterioration of the specimen during transport, and protect anyone that will handle specimen from exposure.
Impressive!

39. 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

40. Preparation and Examination of Stained Specimens
Quick, tentative diagnosis
Differentiation between types of infections
Gram’s stain
Moderate- complexity test
Bacteria either retain or lose purple color
Gram-positive bacteria
Gram-negative bacteria

41. Culturing Specimens in the Medical Office
More common to send specimens for culture to outside labs
Culturing involves placing a sample of specimen on a culture medium
Medium – nutrients
Place in incubator for growth – colony develops as microorganism multiplies

42. Apply Your Knowledge
What are the methods for preparing a slide for direct examination by the physician?
ANSWER: They are wet mount and KOH mount.
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.

43. Apply Your Knowledge 3 for 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.
3 for 3!

44. 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

45. Culturing Specimens (cont.)
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

46. 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

47. 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

48. Apply Your Knowledge Bravo!
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.
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.

49. Quality Control in the Medical Office
Ongoing evaluation of the quality of medical care being provided
Objective means to define, monitor, and correct potential problems
Routine evaluation
All media, staining solutions, and reagents
Equipment

50. Quality Control: Impact of CLIA ’88
Appropriate policies and procedures
Proper documentation
Lab policies and procedures
Materials
Personnel qualifications and training
Participation in proficiency testing program

51. Very Good! Apply Your Knowledge
What is the purpose of a quality control program in the medical office?
ANSWER: To provide an ongoing evaluation of the quality of medical care provided and to provide an objective means to define, monitor, and correct potential problems.
Very Good!

52. In Summary Microorganisms are a major cause of disease
Medical assistant
Collects specimens
Processes or transports specimens
Quality control – ensures quality medical care

53. End of Chapter
End of Chapter 46
Each organism's environment, for the most part, consists of other organisms.
~ Kevin Kelly