NAAT (nucleic acid amplification test) for Chlamydia trachomatis on a first-void urine sample from an asymptomatic 22-year-old woman is positive. The specimen was collected into a validated NAAT transport medium. Which of the following is true about chlamydial NAAT?
- A NAAT on first-void urine has sensitivity 80–90% for C. trachomatis urogenital infection, equivalent to cervical/urethral swab NAAT
- B A positive NAAT result for C. trachomatis in urine should be confirmed by culture before treatment
- C NAAT cannot be used for test-of-cure within 3 weeks of treatment due to detection of dead organism DNA ✓
- D NAAT detects only live organisms and correlates exactly with culture viability
Correct answer: C. NAAT cannot be used for test-of-cure within 3 weeks of treatment due to detection of dead organism DNA
Explanation
NAAT detects nucleic acids (DNA or RNA) and does not distinguish live from dead organisms. After successful treatment, Chlamydia DNA fragments may persist for up to 3 weeks and generate false-positive NAAT results — hence test-of-cure by NAAT should not be performed within 3 weeks of completing therapy. First-void urine NAAT is highly sensitive (82–92%) and is the preferred non-invasive method; sensitivity is equivalent to swab-based NAAT for urogenital chlamydia. NAAT is the gold standard and does not require culture confirmation before treating.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.