Unit #5E – Clinical Laboratory Testing – Basic Clinical Microbiology Includes study of bacteria (bacteriology), parasites (parasitology), viruses (virology) and fungi (mycology) Cecile Sanders, M.Ed., MLS(ASCP)

Unit #5E – 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.

Unit #5E – 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

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Cocci/Diplococci –Bacilli/Rods

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

Unit #5E – 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

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Gram Positive Cocci

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Gram Positive Bacilli – Gram Negative Cocci

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Gram Negative Bacilli

Unit #5E – 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

Unit #5E – 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.

Unit #5E – 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 sories_gbx/filtrationmodules.php sories_gbx/filtrationmodules.php

Unit #5E – 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

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Sterilization - methods used to kill all organisms and their resting stages  EXAMPLE: Autoclaving

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology  Processing of Specimens –Agars - solid medium made of seaweed extract; bacteria grow on these agars and appear as small to large dots  Enrichment agars for growth – contain extra nutrients –Example: Blood Agar

Unit #5E – 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

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology  Selective agars – Inhibit the growth of certain microorganisms while allowing other organisms to grow

Unit #5E – 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

Unit #5E – 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

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology Life cycle of Giardia

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology Life cycle of Ascaris (round worm)

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology Life cycle of amoeba parasite parasite

Unit #5E – 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)

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology  “Wet Prep” for detection of Trichomonas vaginalis

Unit #5E – 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.

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Virus Detection  Most detected by testing for specific antibodies (review #5C PowerPoint)  Some viruses can be cultured –Anatomy of a virus particle – check this website: work/2006/WB_SC_Rimbakusumo/wworks.html work/2006/WB_SC_Rimbakusumo/wworks.html

Unit #5E – 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”

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Molds - filamentous fungi Assorted molds culture Assorted molds culture

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology –Yeasts - unicellular  Usually egg-shaped  Reproduce with buds  Pasty in appearance

Unit #5E – Clinical Laboratory Testing - Basic Clinical Microbiology Photos from clinical microbiology laboratories: