HIV drug resistance is increasing in the UK

The researchers published the results of a study conducted to determine the incidence of transmission of drug resistant HIV- 1 in the United Kingdom.

Participants in their study “were a subset of those enrolled in the UK register of HIV seroconverters, for whom a stored serum or plasma sample was available within 18 months of a negative result in an HIV antibody test or who were found to be infected after having had a negative result in an HIV antibody test in the preceding 18 months.” Drug resistance in the study “was defined as the presence of one or more key mutations in reverse transcriptase or protease recognized as being associated with reduced susceptibility to drugs.” The date of seroconversion was calculated as the “midpoint between the dates of negative and positive antibody tests.”

The researchers reported that of 69 patients infected between June 1994 and August 2000, “60 were infected with subtype B virus (the major subtype in Europe and North America) and nine by non-B (three subtype A, five subtype C, one subtype D). …Ten (14%) had evidence of reverse transcriptase or protease gene mutations associated with drug resistance. In two of the 10 cases, resistance against two of the three available classes of antiretroviral agents was identified.” In their discussion, the researchers reported “preliminary evidence of an increase in the transmission of drug resistant HIV-1 over time in the United Kingdom, with an estimated prevalence of 27% (95% confidence interval 12% to 48%) in people infected in 2000.”

Authors of the study suggested two factors that likely contributed to their findings: “First, highly active antiretroviral therapy is used more often, and the prevalence of drug resistance in people infected with HIV may be increasing. Secondly, as unprotected sex among those at highest risk of HIV infection increases, the likelihood of being infected by a person who has taken antiretroviral drugs is increased.” “Clearly, adherence to treatment in people receiving highly active antiretroviral therapy must be improved in order to minimize the emergence of drug resistance,” they wrote. “In addition, further work is needed to evaluate the impact of primary drug resistance on the outcome of HIV infection in such individuals. Finally, new approaches to encourage safer sexual behaviour within all sectors of the population are urgently needed,” the authors concluded.

UK Collaborative Group on Monitoring the Transmission of HIV Drug Resistance. British Medical Journal (05.05.01) Vol 322: P 1087-1088.