Cases of sexually transmitted diseases such as syphilis, gonorrhea and chlamydia are increasing. A study shows that a single dose of the antibiotic doxycycline could be an effective preventive measure after unprotected sex.
According to a new study, a single dose of doxycycline as the “morning after pill” could prevent the development of bacterial sexually transmitted diseases such as syphilis, gonorrhea or chlamydia: This is what a team led by Dr. Annie Luetkemeyer of the University of California, San Francisco in the New England Journal of Medicine. Around 500 men who have sex with men (MSM) and trans women were enrolled in the study. All were taking HIV pre-exposure prophylaxis (HIV-PREP) or were living with HIV infection. In addition, all of them had been diagnosed with an infection with a sexually transmitted disease (STI) in the year before the start of the study.
For the study, some of the test subjects took 200 mg of doxycycline within 72 hours of having sex without a condom, while the other group did not. This “pill” (more specifically, extended-release tablets) was used an average of four times per month in the first group, with 25 percent taking ten doses or more. The primary endpoint of the study was the incidence of at least one STI per quarter of follow-up. Tests for gonorrhea (clap), chlamydia and syphilis were carried out on a quarterly basis.
The result: The incidence of gonorrhea, chlamydia and syphilis decreased by two-thirds overall when taking doxycycline compared to the other group. The researchers did not report any particular concerns about the side effect profile, safety or acceptability.
What do German experts say about this?
The Science Media Center obtained expert opinions to classify this study result. Privatdozent Dr. Christoph Spinnen from the Klinikum Rechts der Isar of the Technical University of Munich reminds us, for example, that the uncritical use of antimicrobial substances is partly responsible for resistance and problem germs. Appropriate guidelines and recommendations are therefore urgently needed for the transfer of the clinical study results into everyday medical practice, especially in which constellations and target groups the use could be conceivable.
For professor dr. Norbert Brockmeyer from the Ruhr University Bochum and chairman of the German STI Society, the data from the USA cannot be transferred one-to-one to Europe. He emphasizes that the resistance rates for gonococci in the USA with regard to doxycycline, at around 25 percent, are significantly lower than in Europe, at around 60 to 70 percent, and in Germany, at almost 80 percent. One can therefore only expect a reduction in infections with chlamydia and syphilis in the EU. In his statement, Brockmeyer also mentions vaccination with a meningococcal B vaccine for people at risk of gonococcal infection.
DOI: 10.1056/NEJMoa2211934