Bacteriology-Methods Flashcards
What bacteria grow best at 25-30C? (2)
- Yersinia entercolitica
- Psuedomas spp.
Gram Stain Morphology:
-Pyogenic streptoccoci
Gram Positive Cocci
-Pairs/Short chains
Indole Test use/function.
Identification of E. coli (indole Positive)
*not unique to E. coli
What biochemical test is used to identify Group B pyogenic strep and Listeria monocytogenes?
CAMP Test
*Both produce CAMP factor
Gram Stain - Gram Negative features:
- Peptidoglycan*
- Outer membrane
*Staining characteristic
- Thin peptidoglycan cell wall*
- Outer membrane present
*Lose crystal violet/Iodine during decoloarization – Visualized w/ Red Safranin counterstain
Hippurate Hydrolysis Test is used for the presumptive identification of which organisms? (5)
- Campylobacter jejuni
- LIsteria monocytogenes
- Strep agalactiae
- Gardnerella vaginalis
- Legionella pneumophila
*All are POSITIVE
Oxidase Positive Organisms (7)
- Neisseria spp.
- Moraxella
- Pseudomonas
- Legionella
- Campylobacter*
- Vibrio*
- Helicobacter*
*Curved Gram Negative RODS
Gram Stain Morphology:
-Campylobacter
Gram Negative Rods
- Thin, Curved
- S-shaped, Seagull/Corkscrew
Oxidase Negative Organism.
Enterobacteriaceae
What selective media is used for recovery of Neisseria spp. from nonsterile sites?
Thayer-Martin medium
Which organisms don’t grow on Sheep blood agar? (3)
- N. gonorrhea
- H. influenzae
- Legionella
Gram Stain Morphology:
-Staphylococci
Gram Positive Cocci
-Grapelike clusters
Novobiocin Susceptibility testUse/Function.
S. saprophyticus (Novobiacin Resistent) Vs. other coagulase Negative staphylococci
-S. epidermidis (Novobiacin Susceptible)
What selective media is used for recovery of Yersinia spp.?
Cefsulodin-Irgasan-Novobiocin agar
CIN
Growth in Lysozyme containing broth medium is indicative of what bacteria?
Nocardia
Oxidase Test use/function.
Initial classification of Gram Negatives
What medium is used to recover Legionella spp.?
Buffered Charcoal Yeast Extract agar
BCYE
Coagulase Test Use/Function.
S. aureus (Coagulase Positive) Vs. other Staphylococci (Coagulase Negative)
*should always be confirmed using the tube test
Gram Stain Morphology:
-Vibrio spp.
Gram Negative Rods
- Curved, Comma-shaped
- Short rods
Gram Stain Morphology:
-Yersinia pestis
Gram Negative Rods
-Bipolar staining (“Closed Safety-Pin”)
Gram Stain Morphology:
-Nonpyogenic streptococci
Gram Positive Cocci
-Long chains
Gram Stain - Gram Positive features:
- Peptidoglycan
- Outer membrane
*Staining characteristic
- THICK peptidoglycan cell wall*
- NO outer membrane
*Retains purple crystal violet/Iodine stain during the decolarization step (alcohol)
Catalase Test Use/Function.
Gram Positive Cocci
- Staphylococci - Catalase Positive
- Streptococci/Enterococci - Catalase Negative
Why don’t Mycobacteria stain well with Gram Stain?
Mycolic Acids in Peptidoglycan Cell wall
-Hydrophobic-Repels Crystal violet/Iodine
PYR tests use/function.
Identifies Group A pyogenic streptococci and Enterococcus spp.
(Positive Test - Red color change)
Which body sites normally harbor indigenous Anaerobic flora (and should not be cultured for anearobes)? (5)
- Stool
- Skin
- Oropharynx
- Vagina
- Urethra
What selective media inhibits growth of Gram Positive bacteria and many Enterics?
-What does grow?
Selenite Broth
-Samonella
Gram Stain Morphology:
-Neisseria spp.
Gram Negative Diplocci
-Coffee Bean shaped
Listeria monocytogenes - Temperature characteristics.
37C - Optimal growth
25C - Shows motility
4C - Able to multiply
Optochin Susceptibility test (P disk) Use/Function.
S. pneumoniae (Optocin Susceptible*) vs other alpha-hemolytic Streptococci
-Viridans strep (Optocin Resistent)
*Shows Clearing
Besides Staphylococci, what other bacteria are Catalase Positive? (3)
- Campylobacter spp.
- Listeria spp.
- Bacillus spp.
Gram Stain Morphology:
-S. pneumoniae
Gram Positive Diplocci
-Lancet shaped
Acid-Fast Stain principle.
Uses Heat and/or Phenol to allow a Fuchsin dye to penetrate the Hydrophobic barrier
-Stains Mycolic Acids in cell wall
Gram Stain Morphology:
-Enterococcus
Gram Positive Diplocci
Bile Esculin Test Use/Function.
Identifies Enterococci and Group D strep (S. bovis)
What selective media is used for recovery of Vibrio spp.?
Thiosulfate-Citrate-Bile Salts-Sucrose agar
TCBS
Rapid Urease Test use/function.
Proteus spp. and H. pylori identification
-Urease Positive
(Red/Pink coloration)
Gram Stain Morphology:
-Legionella
Gram invisible in primary smear
Campylobacter spp. grows best at what temperature?
42C
