1. Unit #6E – Clinical Laboratory Testing – Basic Clinical Microbiology
Includes study of bacteria (bacteriology), parasites (parasitology), viruses (virology) and fungi (mycology)
Cecile Sanders, M.Ed., MT(ASCP),
CLS (NCA)

2. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Bacteriology
Study of a large diverse group of single celled prokaryote microorganisms which multiply by fission to form a “colony” (on solid media), which can be observed for characteristic appearance.
Bacteria cannot be seen with the naked eye. They can only be seen after staining them with special dyes and observing them under a microscope.

3. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Bacterial Microscopic Morphology
Coccus - round (cocci = plural)
Example: Streps, staphs, Neisseria
Diplococcus - cocci in pairs (diplococci = plural)
Example: Strep. pneumoniae
Bacillus or rods - parallel sides (bacilli = plural)
Example: E. coli
Spirochetes - curved or spiral organisms
Example: Treponema pallidum

4. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Cocci/Diplococci
Bacilli/Rods

5. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Spirochetes

6. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Gram Stain
Most bacteria fall into one of two categories:
Gram-positive = microorganisms that stain purple - Example: Streps, staphs
Gram-negative = microorganisms that stain pink or red - Example: E. coli, Neisseria
Purpose of Gram Stain: Provides valuable information for physician to start antibiotic therapy, as antibiotics act differently on gram (+) vs. gram (-) organisms

7. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Gram Positive Cocci

8. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Gram Positive Bacilli
Gram Negative Cocci

9. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Gram Negative Bacilli

10. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Clinical Bacteriology Terms
Pathogens / pathogenic – capable of causing disease
Communicable - capable of being transferred from one person to another
Normal flora - natural micro-inhabitants of the body
Opportunists / Opportunistic pathogens – organisms that only cause disease in compromised individuals
Antibiotic susceptibility testing – tests for sensitivity of organism against various antibiotics

11. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Specimen collection - Body sites / fluids cultured to grow microorganisms
Fastidious organisms - require special medium / conditions to grow
Aerobic - organisms which require oxygen to grow or live
Anaerobic - organisms which live and grow only in absence of oxygen.

12. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Microbiological Safety Cabinets - H(igh) E(fficiency) P(article) A(ir filter) “HEPA”
Air moves away from worker, over specimen, through filter, and vented to outside

13. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Disinfectants - chemicals used on working areas to kill or control growth of organisms in their active or vegetative stages (NOT resting stages, such as spores). Some harsh disinfectants will kill spores, too
EXAMPLE: 10% bleach, phenols
Antiseptics - chemicals used to control microorganisms on living tissue
EXAMPLE: 70% isoprophyl alcohol, Betadine

14. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Sterilization - methods used to kill all organisms and their resting stages
EXAMPLE: Autoclaving

15. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Processing of Specimens
Agars - solid medium made of seaweed extract
Enrichment agars for growth – contain extra nutrients
Example: Blood Agar

16. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Differential agars – differentiate organisms by color or growth pattern
Example: MacConkey Agar – inhibits the growth of gram positive organisms while allowing gram negative organisms to grow

17. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Selective agars – Inhibit the growth of certain microorganisms while allowing other organisms to grow

18. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Antibiotic Sensitivity (Susceptibility) Testing
Kirby-Bauer Method
MIC – Minimum Inhibitory Concentration – Provides information on weakest dose of antibiotic that would be effective

19. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Parasitology –
Common human parasites
Enterobius vermicularis “Pin Worm”
Giardia lamblia
Trichomonas vaginalis
O & P (Ova and Parasites) - Detection of Intestinal Parasites
Helminths - flatworms, round worms, flukes, or hookworms
Amoeba in cyst or trophozoite stage

20. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Life cycle of Giardia

21. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Life cycle of Ascaris (round worm)

22. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Life cycle of amoeba
parasite

23. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Stool samples - usually collected X3 and at least 24 hours apart
Most common preservative = ParaPak (has two vials, one with Polyvinyl Alcohol [PVA] and the other with formalin)

24. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
“Wet Prep” for detection of Trichomonas vaginalis

25. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Virology
Characteristics
Intracellular parasites
Too small to be seen with light microscopy
Contain either DNA or RNA, but not both
Common viral infections include the common cold, influenza, measles, chickenpox, hepatitis. Others viral infections include polio, HIV, bird flu, West Nile virus.

26. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Virus Detection
Most detected by testing for specific antibodies (review #6C PowerPoint)
Some viruses can be cultured
Anatomy of a virus particle – check this website:

27. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Mycology - study of fungus. Infection with fungus is called a mycosis
Types of Specimens for Fungal Cultures
Skin scrapings
Nail clippings
Scalp scrapings
Sputum
Blood
Bone marrow
Lung biopsies
Fungi (plural of fungus) are either “molds” or “yeasts”

28. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Molds - filamentous fungi
Assorted molds culture

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Yeasts - unicellular
Usually egg-shaped
Reproduce with buds
Pasty in appearance

30. Unit #6E – Clinical Laboratory Testing - Basic Clinical Microbiology
Photos from clinical microbiology laboratories: