Background:  In previous studies, sexually transmitted infections (STI’s) appear to increase seminal HIV-1 shedding in antiretroviral naïve individuals. Conversely, HAART appears to reduce seminal shedding of HIV-1.  However, previous published studies have not investigated the effect of STI’s on seminal shedding of HIV-1 in patients receiving antiretroviral therapy. Since drug-resistant virus may emerge in such individuals, which is then potentially transmissible, estimates of the prevalence of resistant virus in the genital tract during these episodes are required.

Methods:  A prospective case control study of 24 HIV-1 patients on stable HAART regimens and urethritis vs 16 patients on therapy without urethritis was performed. Matched semen and bloods samples were obtained at presentation and at 1 and 2 weeks post-antibiotic treatment.  Quantitative viral load was performed on blood plasma (BP) and seminal plasma (SP). To detect the presence of drug resistance, associated mutations samples with detectable HIV-1 RNA were amplified by in house nested RT-PCR and sequenced using the Beckman CEQ 2000.

Results:  18/24 cases (10 gonorrhoea, 6 chlamydia, 8 non-gonococcal urethritis) and 13/16 controls had undetectable SPVL and BPVL at all visits.  However in 6/24 cases SPVL and BPVL was detectable at the time of STI. Median BPVL and SPVL at the time of infection were 41,457 copies/mL (range <500-98,882) and 11,091 copies/mL (1512-100,000), respectively. At baseline, 4 of 6 semen samples in which genotypic analysis was possible, primary drug resistance associated mutations were detected (2 samples NRTI resistance; 1 sample NRTI+PI; 1 sample NRTI+ NNRTI).   All 4 cases had gonorrhoea and there was minimal discordance between mutational patterns in blood and semen. 2 weeks following antibiotic treatment the median BPVL and SPVL were reduced to 30,125 copies/mL (<500-85,262) and 4156 copies/mL (<900-23,786) respectively in the 6 cases.

Conclusions:  In this case-control study drug resistant HIV was detected in 4 of 24 antiretroviral treated men with STI's.  This must be considered in guiding public health strategies to limit the sexual spread of  drug resistant HIV-1.