Asymptomatic Chlamydia More Prevalent in HIV-Negative Than HIV-Positive Men

Becky McCall

November 18, 2009

November 18, 2009 (Cologne, Germany) — A study conducted at a primary care clinic in Berlin, Germany, of men who have sex with men found that HIV-negative men had a higher prevalence of asymptomatic Chlamydia trachomatis infection than HIV-positive men, contrary to expectation. Overall, the prevalence of C trachomatis and/or Neisseria gonorrhoeae was much higher than expected, at 18%.

In HIV-negative patients, the prevalence of asymptomatic chlamydia and/or asymptomatic gonorrhea was 21%, compared with 14.9% in HIV-positive subjects. For chlamydia alone, HIV-negative patients had a prevalence of infection of 15%, compared with 8.9% in HIV-positive patients. For gonorrhea alone, the prevalence was 6% for HIV-negative patients and 6% for HIV-positive patients.

Heiko Jessen, MD, a primary care physician for infectious diseases in Berlin, Germany, presented the results of the study at the 12th European AIDS Conference/European AIDS Clinical Society (EACS). "Up to 95% of either of these asymptomatic infections go untreated, so this is a reservoir for new infections. This is a nonulcerative STI [sexually transmitted infection], but we believe it increases the risk of acquiring HIV infection. This is the first prospective study in Germany," he told Medscape HIV/AIDS.

Dr. Jessen's team enrolled 100 HIV-positive and 100 HIV-negative men who visited their clinic for any reason. All received an anal and pharyngeal swab for polymerase chain reaction testing, and most returned a questionnaire about sexual history. Duration of HIV infection, CD4 count, and viral load were recorded. Any patients found to be positive for either infection received treatment, but any patients with symptoms of any kind that might be associated with the infections under investigation were excluded, as were patients who had received antibiotic therapy in the 4 weeks prior to the trial and patients in whom if 1 of the 2 infections had been identified in the 12 weeks prior to the trial. Patient age ranged from 18 to 65 years.

The investigators found that 17.9% of HIV-positive and HIV-negative patients were infected with either or both infections. "This is a very high number, higher than the figures in the United States. I had a suspicion there was a problem, but this is very high. In Germany, we don't have STI walk-in clinics, which we need for all groups, but especially for gay men." said Dr. Jessen.

There were 36 patients infected with 41 infections. Five had 2 infection sites or infections with both pathogens. The most frequent infection was chlamydia in the anus, followed by gonorrhea in the anus. "Frustratingly, only around 45% of HIV-positive and 55% of HIV-negative patients claimed they always used condoms in the [previous] month. This is concerning because when people have an STI in addition to HIV, then they are more likely to pass on HIV," he added. In addition, the HIV-negative patients might acquire HIV more easily.

Dr. Jessen found that men who had had HIV for a longer time had fewer STIs than those who had more recent infection. "Those who have had HIV for longer are likely to have been on antiretroviral therapy for longer. It would be interesting to find out if the treatment has any affect on other STIs through some influence on the immune system."

Among other study findings, Dr. Jessen reported that men who had had sex in the previous 4 weeks, particularly anal sex, had a higher likelihood of asymptomatic chlamydia or gonorrhea. There was no association between age and rate of infection with either chlamydia or gonorrhea.

The researchers also reported that 3.4% of HIV-negative patients required repeat treatment of persistent infections, compared with 13.8% of HIV-positive subjects.

Jürgen Rockstroh, MD, professor of medicine at the University of Bonn in Germany, and cochair of EACS, believes the study provides important and relevant information on the presence of STIs in both HIV-positive and HIV-negative populations of men who have sex with men. "If we don't screen for these, we won't find them. This underlines the quest to have a certain underlying STI screening service in place. In Germany, we don't have STI screening clinics with a standardized approach."

His interpretation of the finding that more HIV-negative men experienced asymptomatic chlamydia than HIV-positive men suggests the importance of monitoring. "I think this has something to do with the fact that HIV-positive men are more likely to seek regular medical [attention]. They are more likely to see the doctor every 3 months or so and discuss various odd sensations, so it is more likely that STIs will be found."

This study received funding from Abbott and GSK. Dr. Jessen has disclosed no relevant financial relationships. Dr. Rockstroh reports receiving funding and consultancy fees from Abbott, BMS, Gilead, Boehringer Ingelheim, Roche, MSD, Pfizer, Merck, Vertex, and Schering.

12th European AIDS Conference/European AIDS Clinical Society (EACS): Abstract 13.4. Presented November 13, 2009.

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