Genotypic resistance to antiretroviral drugs in patients with therapeutic failure to highly active antiretroviral therapy

BACKGROUND: TO assess genotypic resistance mutations in patients with virol ogical failure with highly active antiretroviral therapy (HAART) METHODS: Genotyping of reverse transcriptase (RT) and protease (PRO) HIV-I genes were carried out in 33 adherent patients failing on HAART. RESULTS: Resistance mutations were found in 32 of the 33; 27 of them (81.8% ) being primary mutations: 26 (78.8%) in the RT gene and 60 (60.6%) in the PRO gene. Overall, 66.6% had genotypic resistance to two drugs and 60.6% sh owed resistance to drugs belonging to the two main classes of antiretrovira l drugs. At the time of treatment failure, 72.7% had on their therapeutic r egimen one antiretroviral drug to which they had resistance mutations, 48.5 % had genotypic resistance to two drugs of the therapeutic regimen and 21.2 % to three drugs. CONCLUSIONS: Most adherent patients failing on HAART carry drug resistant g enotypes. These patients may constitute a reservoir of multidrug resistant HIV that may limit treatment options in the future.