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Microbiology Flashcards

6 cards from real ASCP practice questions. Tap to flip, then mark Knew It or Still Learning โ€” missed cards come back until you master them.

Read the first 6 Microbiology flashcards as text
  1. Which culture medium is used for isolation of Neisseria gonorrhoeae?

    Answer: Thayer-Martin agar

    Modified Thayer-Martin agar contains antibiotics (vancomycin, colistin, nystatin) to select for Neisseria species from genital specimens.

  2. Acid-fast bacilli seen on Ziehl-Neelsen stain are most consistent with:

    Answer: Mycobacterium tuberculosis

    Mycobacterium tuberculosis retains carbol fuchsin after acid-alcohol decolorization due to its mycolic acid-rich cell wall.

  3. A positive oxidase test (purple color) differentiates which organism from Enterobacteriaceae?

    Answer: Pseudomonas aeruginosa

    Pseudomonas aeruginosa is oxidase-positive (contains cytochrome c oxidase), while all Enterobacteriaceae are oxidase-negative.

  4. Which toxin produced by Clostridium difficile causes pseudomembranous colitis?

    Answer: Toxin A (enterotoxin) and Toxin B (cytotoxin)

    C. difficile produces Toxin A (enterotoxin) and Toxin B (cytotoxin), both detected in stool EIA or PCR testing for diagnosis.

  5. India ink preparation is used to visualize the capsule of which organism in CSF?

    Answer: Cryptococcus neoformans

    India ink stain creates a dark background, highlighting the large capsule of Cryptococcus neoformans as a clear halo.

  6. Which antibiotic resistance mechanism involves enzymatic destruction of the beta-lactam ring?

    Answer: Beta-lactamase production

    Beta-lactamases hydrolyze the beta-lactam ring of penicillins and cephalosporins, rendering them inactive.