Background: Failure of antiretroviral drugs to completely suppress HIV-1 replication inevitably leads to selection of drug-resistant variants. Emergence of drug resistance plays a major role in limiting the long-term success of antiretroviral therapy.
Material and methods: From August 1998 until April 2001, a total of 183 samples from 152 patients were analysed for HIV-1 drug resistance using genotypic analysis.
Results: Mutations associated with resistance were found in virus from 112 patients who received antiretroviral therapy. Mutations were frequently identified in the reverse transcriptase gene and to a lesser extent in the protease gene. Mutations associated with reduced drug susceptibility or polymorphisms were identified in 22 treatment naive patients. In addition, resistance mutations were observed in three out of eight patients with a recent infection.
Interpretation: Genotypic resistance testing is a valuable tool for rational decision-making when the current therapy is failing. In addition, patients with a recent HIV-1 infection should be tested for the surveillance of transmission of drug-resistant genotypic variants.