High prevalence of HIV-1 drug resistance among patients on first-line antiretroviral treatment in Lomé, Togo.

backgroundWith widespread use of antiretroviral (ARV) drugs in Africa, one of the major potential challenges is the risk of emergence of ARV drug-resistant HIV strains. Our objective is to evaluate the virological failure and genotypic drug-resistance mutations in patients receiving first-line highly active antiretroviral therapy (HAART) in routine clinics that use the World Health Organization public health approach to monitor antiretroviral treatment (ART) in Togo.

methodsPatients on HAART for one year (10-14 months) were enrolled between April and October 2008 at three sites in Lomé, the capital city of Togo. Plasma viral load was measured with the NucliSENS EasyQ HIV-1 assay (Biomérieux, Lyon, France) and/or a Generic viral load assay (Biocentric, Bandol, France). Genotypic drug-resistance testing was performed with an inhouse assay on plasma samples from patients with viral loads of more than 1000 copies/ml. CD4 cell counts and demographic data were also obtained from medical records.

resultsA total of 188 patients receiving first-line antiretroviral treatment were enrolled, and 58 (30.8%) of them experienced virologic failure. Drug-resistance mutations were present in 46 patients, corresponding to 24.5% of all patients enrolled in the study. All 46 patients were resistant to non-nucleoside reverse-transcriptase inhibitors (NNRTIs): of these, 12 were resistant only to NNRTIs, 25 to NNRTIs and lamivudine/emtricitabine, and eight to all three drugs of their ARV regimes. Importantly, eight patients were already predicted to be resistant to etravirine, the new NNRTI, and three patients harboured the K65R mutation, inducing major resistance to tenofovir.

conclusionsIn Togo, efforts to provide access to ARV therapy for infected persons have increased since 2003, and scaling up of ART started in 2007. The high number of resistant strains observed in Togo shows clearly that the emergence of HIV drug resistance is of increasing concern in countries where ART is now widely used, and can compromise the long-term success of first- and second-line ART.