Seroconversion on preexposure prophylaxis: a case report with segmental hair analysis for timed adherence determination

Abstract

Objective: We describe the third case report of seroconversion with multidrug resistant (MDR)-HIV despite pre-exposure prophylaxis (PrEP) with emtricitabine (FTC) and tenofovir (TFV) disoproxil (TDF).

Design: Case report.

Methods: PrEP adherence was assessed via self-report, pharmacy records, and measuring TFV/FTC levels with liquid-chromatography/tandem-mass-spectrometry in plasma and hair. Segmental hair analysis was performed to assess PrEP adherence over prior months. Genotypic resistance was assessed.

Results: A 34 year-old white MSM started daily FTC/TDF in February 2016 after being provided 11 refills. In March 2017, he developed fevers, chills, myalgias and was assessed, but no HIV test was sent. In April 2017, an antigen/antibody HIV test was reactive (day 0). On day 2, HIV-1 RNA was 27 316 copies/ml, genotyping revealed M184V, K70T, K65R, and K103N mutations, plasma TFV and FTC concentrations were consistent with recent dosing. To evaluate adherence over preceding months, a hair sample was collected at day 27 and segmental analysis of TFV/FTC levels performed in one-centimeter segments from the scalp. Hair drug levels (0.0434-0.0520 ng TFV/mg hair) were commensurate with consistently high PrEP adherence over the prior 3 months.

Conclusions: This study employs segmental analysis of PrEP drug levels in hair for the first time to assess adherence over preceding months in the setting of an HIV seroconversion on PrEP. High adherence over the period of likely acquisition makes MDR-HIV infection the most likely scenario in this case. Adequate adherence assessment when examining PrEP failures and ensuring best practices in PrEP prescribing and follow-up are important.

Fig. 1.. Segmental hair analysis in patient on tenofovir disoproxil fumarate–emtricitabine-based preexposure prophylaxis who seroconverted.

Dates show first positive HIV test (day 0), as well as time over which adherence was assessed by hair concentrations in the University of California, San Francisco Hair Analytical Laboratory. Data from a dose-concentration study called STRAND [4] allows us to estimate number of doses per week from tenofovir levels in hair.