Intro to Microbiology Flashcards
Normal Microbiota in Skin
Staphylococcus epidermis: can colonize plastic catheters
Staphylococcus aureus: causes skin infections
Propionibacterium acnes: acne, anaerobic. Produces green pigment / fruity smell. Gram negative.
Normal Microbiota in Mouth / Nose
Streptococcus mutans: colonize teeth / gingival tissue.
Can enter bloodstream after dental surgery. Colonize dmg or prosthetic heart valves, leading to potentially fatal infective endocarditis
Streptococcus pneumoniae: cause pneumonia
Normal Microbiota in Intestinal Tract
Urea -> ammonia cloud surrounds H. Pylori
Largest number of bacteria.
Normal Microbiota in Urogenital Tract
Lactobacillus species: maintain low pH in vagina. If urine is not sterile, you have infection.
Diagnostic Microbiology: gram stain, acid-fast stain, india ink, potassium hydroxide
Gram Stain
Gram positive : Purple
Gram negative : Pink/red
Crystal Violet, Iodine, acetone, safranin, check. Iodine traps crystal violet within peptidoglycan
Acid-fast Stain: pink/red when positive. Checks for organisms with large amounts of FAs.
India Ink: look for capsules
Potassium Hydroxide Prep: fungi recognized
Catalase, Oxidase, Coagulase, Urease Test
Catalase Test:
Degradation of H2O2. Staphylococci = + Streptococci = -.
Oxidase Test:
Look for complex 4 (cytochrome c oxidase). Detect Pseudomonas aeruginosa (+) or Enterobacteriaceae (-)
Coagulase Test:
Forms clot. Differentiate staphylococcus aureus vs staphylococci
Urease Test:
Urea -> ammonia and CO2. Detect pH change.
Quellung Reaction, Latex Agglutination, Complement Fixation, ELISA, Western Blotting, Fluorescent Antibody Tests
Quellung Reaction: find capsule
Latex Agglutination: check for agglutination of antibody
Complement Fixation: Pink = negative. Look for patient’s serum antibody. Ability for
antibody to bind complement
ELISA: check for antibody
Western BLotting: check protein
Fluorescent antibody tests: check antibodies
