Bacterial identification, culture media, and staining and biochemical test interpretation tested on ASCP microbiology sections.
40 cards · basic cards · AI-written, checked twice. Edit anything.
- What is the primary purpose of a Gram stain?
- To differentiate bacteria into gram-positive and gram-negative groups based on cell wall structure
- What color do gram-positive organisms appear after Gram staining?
- Purple (they retain crystal violet)
- What color do gram-negative organisms appear after Gram staining?
- Pink or red (they retain the safranin counterstain)
- What type of agar selectively grows gram-negative organisms while inhibiting gram-positive growth?
- MacConkey agar
- What does lactose fermentation on MacConkey agar indicate?
- The organism is a lactose fermenter, producing pink colonies (such as E. coli)
- What is blood agar used for?
- General purpose growth and observing hemolysis patterns
- What is alpha hemolysis on blood agar?
- Partial hemolysis producing a greenish discoloration around colonies
- What is beta hemolysis on blood agar?
- Complete hemolysis producing a clear zone around colonies
- What is gamma hemolysis?
- No hemolysis (no change to the agar around colonies)
- What organism is classically catalase-positive, coagulase-positive, and beta-hemolytic?
- Staphylococcus aureus
- What test distinguishes Staphylococcus species from Streptococcus species?
- The catalase test (Staphylococcus is catalase-positive, Streptococcus is catalase-negative)
- What test distinguishes Staphylococcus aureus from coagulase-negative staphylococci?
- The coagulase test (S. aureus is coagulase-positive)
- What organism does the optochin susceptibility test identify?
- Streptococcus pneumoniae, which is optochin-sensitive
- What organism does the bacitracin susceptibility test identify?
- Group A Streptococcus (Streptococcus pyogenes), which is bacitracin-sensitive
- What does the oxidase test differentiate?
- Enterobacteriaceae (oxidase-negative) from other gram-negative rods like Pseudomonas (oxidase-positive)
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