Microbial diagnostics · USMLE Step 1

A microbiology lab identifies Gram-negative diplococci in a urethral smear from a symptomatic male. What is the next best confirmatory step?

  1. PCR for Neisseria gonorrhoeae
  2. Tube coagulase test
  3. Catalase enzyme test
  4. Rapid urease test
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Correct answer: PCR for Neisseria gonorrhoeae

PCR is sensitive and specific for N. gonorrhoeae and is widely used for confirmation. Culture is less sensitive but still possible.

Difficulty: Medium Question 5 of 20

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