Prevalence of rilpivirine resistance in people starting antiretroviral treatment in Argentina.

BACKGROUND: Rilpivirine-based regimens are now preferred or alternative first-line regimens according to many HIV treatment guidelines. Recently, a surveillance study conducted in Argentina determined that prevalence of pretreatment resistance to first-generation non-nucleoside reverse transcriptase inhibitors (NNRTIs) was 10%. The aim of this study was to analyse the prevalence of resistance mutations to newer generation NNRTIs in the population starting ART in Argentina.

METHODS: We analysed the prevalence of resistance mutations to rilpivirine and etravirine (according to the IAS list), obtained through a nationally representative pretreatment HIV-drug resistance (PDR) surveillance study performed in Argentina in 2014-2015. Briefly, 25 ART-dispensing sites throughout the country were randomly chosen to enrol 330 adults starting ART. Samples were processed with Trugene (Siemens)® and analysed using the Stanford algorithm.

RESULTS: All 270 samples corresponding to participants with no prior exposure to antiretroviral drugs were included in this analysis. Median (IQR) age was 35 years (28-43); 66.7% were male; median (IQR) CD4+ T-cell count was 284 cells/mm3 (112-489). The prevalence of resistance to any antiretroviral was 16% (±5%) and prevalence of NNRTI RAMs was 13% (±4%). The prevalence of resistance to rilpivirine was 8% (±3%). Prevalence of resistance to etravirine was 4% (±3%). The most frequent mutations conferring resistance to rilpivirine were: E138A (n=6) and G190A (n=4).

CONCLUSIONS: This PDR surveillance study showed concerning levels of HIV drug resistance (HIVDR) in Argentina, not only for first-generation NNRTIs but also to rilpivirine. In our setting, performing resistance testing would be necessary before prescription of ART even if a second-generation NNRTI-based regimen was used as first-line therapy.