[Application of HIV drug resistance testing according to guidelines]

Guidelines for application of HIV drug resistance testing have recently been develeped in Europe and the USA. This article discusses these recommendations. Since the widespread use of highly active antiretroviral therapy (HAART), quality of life has been improved for the majority of HIV-infected patients and the mortality rate has declined significantly. However, an incomplete suppression of viral replication results in selection of resistant viral strains resulting in a loss of HAART efficacy and worsening in the quality of life. Resistance testing is likely to improve virological monitoring of untreated but especially in pre-treated patients. Genotypical and phenotypical assays present similar results, but genotypical testing is the method of choice initially. Translation of resistance testing into clinical decisions-making requires consideration of a patient's history, interpretation of results by a validated algorithm, and expert advice. Problems of adherence should be avoided by counselling and therapeutic drug monitoring. Resistance testing or storage of a patient's plasma sample should be undertaken as early as possible in the disease history. If this is not possible, treatment with HAART, including a boosted protease inhibitor, is warranted. European and USA guidelines present similar recommendations. HIV drug resistance is preventable by rational choice of drug combinations in HAART. After development of resistance-associated mutations, drug resistance testing can preserve future treatment options and preventing further clinical deterioration. The method has been incorporated into national and international guidelines on the basis of good scientific evidence.