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?
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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?
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Purple (they retain crystal violet)- What color do gram-negative organisms appear after Gram staining?
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Pink or red (they retain the safranin counterstain)- What type of agar selectively grows gram-negative organisms while inhibiting gram-positive growth?
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MacConkey agar- What does lactose fermentation on MacConkey agar indicate?
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The organism is a lactose fermenter, producing pink colonies (such as E. coli)- What is blood agar used for?
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General purpose growth and observing hemolysis patterns- What is alpha hemolysis on blood agar?
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Partial hemolysis producing a greenish discoloration around colonies- What is beta hemolysis on blood agar?
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Complete hemolysis producing a clear zone around colonies- What is gamma hemolysis?
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No hemolysis (no change to the agar around colonies)- What organism is classically catalase-positive, coagulase-positive, and beta-hemolytic?
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Staphylococcus aureus- What test distinguishes Staphylococcus species from Streptococcus species?
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The catalase test (Staphylococcus is catalase-positive, Streptococcus is catalase-negative)- What test distinguishes Staphylococcus aureus from coagulase-negative staphylococci?
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The coagulase test (S. aureus is coagulase-positive)- What organism does the optochin susceptibility test identify?
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Streptococcus pneumoniae, which is optochin-sensitive- What organism does the bacitracin susceptibility test identify?
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Group A Streptococcus (Streptococcus pyogenes), which is bacitracin-sensitive- What does the oxidase test differentiate?
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Enterobacteriaceae (oxidase-negative) from other gram-negative rods like Pseudomonas (oxidase-positive)
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