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Microbiology Basics Flashcards

7 cards from real CMLA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Microbiology Basics flashcards as text

  1. Which viral hepatitis is transmitted primarily through the fecal-oral route?

    Answer: Hepatitis A

    Hepatitis A virus (HAV) is transmitted via contaminated food and water (fecal-oral route), unlike hepatitis B and C which spread parenterally.

  2. What is the function of a mordant in the Gram staining procedure?

    Answer: Fix the crystal violet–iodine complex to the cell wall

    Gram's iodine acts as a mordant, forming an insoluble crystal violet–iodine complex that becomes trapped within the thick peptidoglycan of Gram-positive cell walls.

  3. Clostridium difficile is best detected in stool specimens using which laboratory method?

    Answer: EIA or PCR for toxins A and B

    Enzyme immunoassay (EIA) for C. difficile toxins A/B or PCR-based molecular testing for toxin genes are the preferred diagnostic methods for C. difficile infection.

  4. The oxidase test detects the presence of which enzyme in bacteria?

    Answer: Cytochrome c oxidase

    The oxidase test uses a reagent (tetramethyl-p-phenylenediamine) that turns purple when reduced by cytochrome c oxidase, an enzyme in the electron transport chain.

  5. Which organism is a common cause of nosocomial (hospital-acquired) urinary tract infections and is known for its characteristic grape-like odor?

    Answer: Pseudomonas aeruginosa

    Pseudomonas aeruginosa produces pyocyanin and has a distinctive grape-like or fruity odor; it is a leading cause of healthcare-associated infections, especially in immunocompromised patients.

  6. Which stain is used to visualize Cryptococcus neoformans capsule in cerebrospinal fluid?

    Answer: India ink preparation

    India ink (or nigrosin) creates a dark background that outlines the large polysaccharide capsule of Cryptococcus neoformans as a clear halo in CSF specimens.

  7. Beta-lactamase production by bacteria causes resistance by:

    Answer: Enzymatically destroying the beta-lactam ring of antibiotics

    Beta-lactamases hydrolyze the beta-lactam ring that is essential for the antibiotic's activity, rendering penicillins and cephalosporins inactive before they can inhibit cell wall synthesis.