Over 27% of gay men in England, Wales and Northern Ireland in 2002 with recently acquired HIV had been infected with a drug-resistant strain of HIV, according to a poster presentation to the Fifteenth International AIDS Conference in Bangkok on July 14th. The investigators from the UK Health Protection Agency also found that the prevalence of drug resistant HIV was even higher in men with an acute sexually transmitted infection and suggest that routine resistance testing at the time of HIV diagnosis should become standard.
Individuals attending for sexual health screens at genitourinary medicine clinics in the UK are routinely asked to consent to the anonymous unlinked testing for HIV of their blood sample obtained for syphilis testing.
Investigators used samples obtained through this programme to determine trends in the transmission of drug resistant HIV in gay men with recent HIV infections in England, Wales and Northern Ireland between 1999 and 2002. As individuals with recent infection identified by anonymous unlinked testing would be unaware of their HIV status they would not have had the opportunity to take antiretroviral therapy and therefore the presence of drug resistant virus in samples would indicate that it had been sexually transmitted.
Over 26,000 samples were collected from 15 clinics. If available, clinics provided with each sample information on age, sexual orientation, world region of birth, and whether an individual was infected with an acute sexually transmitted infection.
Samples from gay men that tested positive for HIV were screened by a testing algorithm to determine if they had a recently acquired infection.
These samples were then tested for resistance to both protease inhibitors and reverse transcriptase inhibitors.
A total of 243 recent infections in gay men were identified between 1999 and 2002. Of these 30 involved infection with a drug resistant strain of HIV. Two samples involved infection with virus that was resistant to drugs from more than one class.
The proportion of samples involving infection with drug resistant virus increased from 20.3% in 2001 to 27.3% in 2002.
Differing trends were identified for the transmission of HIV with resistance to reverse transcriptase inhibitors and to protease inhibitors. High-level resistance to reverse transcriptase inhibitors fell from 1999 to 2001, before increasing slightly in 2002. By contrast, the transmission of virus with high-level resistance to protease inhibitors increased until 2001 before falling slightly.
The most common mutation conferring resistance to protease inhibitors was L90M and the most common mutation in reverse transcriptase was M41L.
An acute sexually transmitted infection was present in 39.5% of gay men recently infected with drug resistant HIV. In total 90% gay men recently infected with drug resistant HIV were aged between 20 and 44. The prevalence of drug resistance in samples collected within London and outside London was similar. Almost all infections (94.5%) involved HIV subtype B.
“The data from 2002 suggest that over 27% of recent HIV infections in [gay men] had mutations consistent with drug resistance. This may lead to suboptimal first line therapy with reduced health benefit for the patients,” conclude the investigators. They add that “further spread of resistant viruses is likely because of the high prevalence of resistance in individuals with high risk sexual behaviour” and recommend that “routine resistance testing at the time of first diagnosis should become part of standard” HIV care.
Rinck G et al. Trends in transmitted antiretroviral drug resistance in men who have sex with men attending genitourinary medicine clinics in England, Wales and Northern Ireland. XV International AIDS Conference, Bangkok, abstract PpC4713, 2004.