An update is given on the epidemiology of transmitted antiretroviral drug resistance among HIV-1-infected adults.
Reported prevalence surveys show inter-region and intra-region variability, in part as a result of methodological differences. Temporal trends are difficult to define as rates appear stable or declining in some cohorts but increasing in others. While the highest prevalence continues to be observed in North America, Western Europe and areas of South America, transmitted antiretroviral drug resistance is emerging in countries where access to therapy is being scaled up, including regions of sub-Saharan Africa. Resistance patterns in drug-experienced and drug-naïve persons, transmission efficiency of resistant variants and their ability to persist as dominant species in the absence of drug pressure determine the prevalence of resistance mutations in persons with transmitted antiretroviral drug resistance. The most frequently detected mutations are in reverse transcriptase, especially thymidine analogue mutations, whereas protease mutations other than natural polymorphisms are generally less prevalent.
A consensus is required internationally on how transmitted antiretroviral drug resistance should be investigated and reported. Although routine testing methods provide only minimal estimates of the prevalence of transmitted antiretroviral drug resistance, successful treatment outcomes are observed in patients with resistance receiving first-line therapy guided by baseline resistance testing.
Royal Free Hospital and Royal Free and University College Medical School, London, UK
Correspondence to Dr Anna Maria Geretti, MD, MSc, PhD, MRCPath, Department of Virology, Royal Free Hospital, Pond Street, London NW3 2QG, UK Tel: +44 (0)20 7794 0500; fax: +44 (0)20 7830 2854; e-mail: email@example.com
Sponsorship: Dr Geretti has received Consultancy and/or Speaker fees from the following: Abbott Diagnostics, Abbott Pharmaceuticals, Boehringer Ingelheim, Bristot-Meyers Squibb, Gilead Sciences, GlaxoSmithKline, Medivir, Pfizer, Roche Pharmaceuticals, Tibotec and Virco.