[Resistance in HIV therapy. Which cases profit from resistance testing]

Although resistance tests are widely recommended, definitive and convincing data on the indication for, and the potential benefits of, such tests are not available. In the present article, the major basics and data of importance for the use of such tests in the clinical setting are presented and discussed. Resistance is not a routine investigation, but in specific cases it could lead to an improvement in the selection of the (optimal) antiretroviral drug. In the majority of cases, however, in particular in the case of multiple pretreated patients, little benefit is to be expected. In any case, a specialist should be available prior to and following such testing. Many questions will be answered only after further prospective studies.