Drug resistance in patients experiencing early virological failure under a triple combination including indinavir

Abstract
To assess the pattern of drug resistance mutations selected in HIV-1-infected patients failing a first line triple combination therapy including indinavir. Plasma samples from 87 patients collected at the time of the first virological rebound (> 50 HIV-RNA copies/ml) were examined for the presence of drug-resistant genotypes. The mean level of plasma viraemia at rebound was 7824 HIV-1 RNA copies/ml in 73 subjects with good compliance, whereas it was 359 460 HIV-1 RNA copies/ml in 14 patients who admitted to poor adherence. Genetic sequence analysis yielded results for 51 (70%) of the patients having good adherence. More than half of them (26/51, 51%) carried primary mutations associated with resistance to nucleoside analogues. In contrast, primary protease inhibitor resistance mutations were recognized less frequently (14/51, 27%; P The overall rate of drug-resistant HIV genotypes was 38% (28/73) in patients with good adherence and who were experiencing a first virological failure under a triple combination regimen including indinavir; resistance to nucleoside analogues was more frequent than resistance to indinavir. Therefore, treatment intensification in those patients without resistance, or a selective substitution of nucleosides in those with resistance limited to these compounds, might be justified.