A 6-week-old infant born to an HIV-infected mother who did not receive antiretroviral prophylaxis is tested with a standard third-generation HIV antibody ELISA, which returns positive. The correct next step is:

• A Perform HIV-1 DNA or RNA PCR (nucleic acid testing) now to establish the diagnosis ✓
• B Repeat antibody testing at 18 months before drawing any conclusion
• C Start antiretroviral therapy immediately since the test confirms infection
• D Disregard the result because vertical transmission never occurs without prophylaxis failure

Explanation

Transplacental maternal IgG persists in the infant up to 18 months, so any antibody-based assay before that age reflects maternal status and cannot diagnose infant infection. Definitive diagnosis in infancy requires virologic testing, namely HIV-1 DNA PCR or plasma RNA PCR, recommended at birth or by 6 weeks. Option B delays necessary care, and option C treats an unconfirmed diagnosis.

Reference: Nelson Textbook of Pediatrics, 22nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.