Over the last few years, the prevalence of transmitted
HIV-1 drug resistance (TDR) has not risen in the industrialised countries of western Europe. As recently reported by the European surveillance programme monitoring the spread of
HIV resistance (SPREAD), the overall prevalence of TDR in drug-naïve individuals who have been newly diagnosed with
HIV is stable at 9%. In most countries, genotypic resistance analysis is routinely performed before antiretroviral treatment initiation and national drug-resistance databases have been established as central repositories for resistance results. Incomplete suppression of viral replication caused by insufficient drug levels, low adherence, compartmentation and individual pharmacogenetic characteristics of the patient are important factors influencing TDR. Since the development of second-generation and new antiretroviral drug classes, treatment options for patients infected with
HIV have significantly improved. However, the analysis of resistance pathways to new