[HIV resistance. More the rule than an exception]

Resistance-associated mutations of the HIV genome are one major reason for failure of highly, active antiretroviral therapy. The accumulation of resistance is demonstrated by data from the HCUS-study, where resistant virus strains were isolated in about 50%. More than 60% of the patients showed therapy failure in this survey, and resistance was found in almost 80% of these. Mutations in the HIV genome were also described in treatment-naive patients. In the German Seroconverter Study the rate of resistance was 12%, in a multicenter study in Nordrhein-Westfalen resistant isolates were found in 14% of chronically infected cases. The wide distribution of HIV resistance in treated and untreated patients is an important problem in the management of HIV-infection. It requires a rational application of resistance testing. International studies are under way to further characterize the relevance of the phenomenon of HIV resistance.