September 6, 2012
Delivette Castor et al. J Acquir Immune Defic Syndr 2012;61:1-8. Read the abstract.
A dictum of antimicrobial therapy is the more you use, the more you lose (as in microbe sensitivity to the drugs that get prescribed often). With HIV treatment, this has generally been the case. Resistance to antiretrovirals follows widespread use and then can be transmitted to others, compromising treatment response in the unfortunate recipient of said virus. Interestingly, the level of transmitted resistance seems to be fairly stable in the developed world, with changes seen not so much in the proportion infected with drug-resistant HIV, but in which antiretrovirals the virus is resistant to.
In New York City, where the incidence of HIV among MSM is high, a collaborative research team examined 600 cases of acute or recent (within a year) HIV infection from 1995 to 2010 to describe trends in acquired antiretroviral resistance and also the clustering of these cases based on phylogenetic analyses. Remarkably, 97% of the cases were male. Overall, 68% were non-Hispanic white, but the proportion who were black increased significantly over time and was up to 12% in the most recent time period -- commensurate with the shift of the domestic HIV epidemic toward black MSM.
The rate of transmitted drug resistance was stable across the study period at around 14% (declining slightly to 11% during the most recent time period). However, there were changes in the patterns of resistance, such that nucleoside reverse transcriptase inhibitor (NRTI) resistance fell from 15% to 3% over time (P = .005), while NNRTI resistance increased from 3% to 8% (P = NS, although there was a strong trend for mutations at 103 position). PI as well as dual- and triple-class resistance were not detected during the last year of observation.
The clustering analyses found that 19% to 27% of the cases co-clustered and that clustering increased over time. Demographic and other characteristics, such as the use of the Internet to find partners, were not associated with clustering, suggesting the dynamics of transmission of HIV in NYC are complex and difficult to elucidate in a relatively small study.
Overall, this work helpfully makes clear the rise and plateau of transmitted NNRTI resistance among MSM. The continued ability of this cohort to add participants, and the increased proportion of cases that were among black MSM, also demonstrates that transmission of HIV is not slowing down. Lastly, the study also underscores the need for a screening genotype during acute/recent infection and before HIV therapy is started.
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