In a patient with suspected CMV retinitis (HIV-positive, CD4 18 cells/µL), plasma CMV DNA quantification by quantitative real-time PCR shows 48,000 IU/mL. What is the significance of viral load monitoring during treatment?

• A CMV DNA level predicts retinal detachment risk only, not treatment response
• B Antigen (pp65) detection in WBCs is superior to PCR for monitoring
• C Single baseline CMV DNA load determines whether ganciclovir or foscarnet is used
• D Serial CMV DNA quantification guides duration of induction therapy and confirms treatment response (target: ≥1-log10 decrease in 3 weeks) ✓

Explanation

Quantitative CMV DNA PCR is the gold standard for both diagnosing CMV end-organ disease in HIV patients and monitoring treatment response. During induction therapy with IV ganciclovir or oral valganciclovir, a ≥1-log10 reduction in CMV DNA by 3 weeks indicates adequate response. Persistent high-level viraemia or rising viral load despite therapy suggests ganciclovir resistance — prompting genotypic resistance testing (UL97 kinase mutations first, then UL54 polymerase mutations) and switch to IV foscarnet or cidofovir. CMV pp65 antigenemia is less sensitive than PCR in severely immunocompromised patients (low neutrophil count reduces sensitivity).

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.