A morning-after pill against syphilis, gonorrhea or chlamydia

Bbacterial sexually transmitted diseases such as syphilis, gonorrhea or chlamydia are still widespread in Germany, particularly among men who have sex with men (MSM). The infections are often asymptomatic and are therefore not treated at all – which can not only lead to serious consequences for those affected, but also promotes the transmission of these diseases.

In 2018, a Germany-wide study of 2,303 gay men gave an impression of the extent of the problem. Within the study period between February and July 2018, almost one in three of those who were regularly tested had been infected with at least one of the sexually transmitted diseases (STI) examined. This was particularly the case among those individuals who were also taking concomitant pre-exposure prophylaxis (PrEP) against human immunodeficiency virus (HIV) and who therefore probably refrain from using a condom.

The development of a “morning after pill” that could prevent infection would therefore be an important step. A recent study published in the renowned New England Journal of Medicine could now provide just such a pill. An antibiotic is presented there that should be taken within 72 hours after unprotected sex without a condom. The researchers tested the drug in a randomized trial of 501 participants who were MSM and trans women who were taking PrEP or living with HIV infection. Participants also had a gonococcal infection within the year prior to study enrollment, Chlamydia trachomatis or syphilis.

Significantly fewer infections

Subjects were randomized 2:1 to take 200 milligrams of doxycycline (doxycycline post-exposure prophylaxis, DoxyPEP) within 72 hours of unprotected sex or standard of care without doxycycline, and tested quarterly for syphilis, gonorrhea, and chlamydia. The result of the study is encouraging: in the group that took doxycycline, the number of infections with syphilis, gonorrhea or chlamydia was reduced by two-thirds compared to the control group.

“The data show that the use of DoxyPEP as a single dose after a high-risk contact in this patient group appears to be effective,” Georg Stary, from the Medical University of Vienna, told Germany’s Science Media Center. “It is known that patients who take HIV PrEP to protect themselves from contracting HIV frequently engage in unprotected sex and some of these become infected with many sexually transmitted pathogens. In this special subgroup, the use as a prophylactic seems to offer a great advantage.” If this could prevent infections, this could also be a protection for those who do not take the drug.

On average, the test participants took the pill four times a month, and one in four used it ten times or more – which, however, also increases the risk of antibiotic resistance occurring. The uncritical use of antimicrobial substances is ultimately partly responsible for such resistances and the occurrence of problem germs, pointed out the infectiologist Christoph Spinner from the Rechts der Isar Clinic at the Technical University of Munich. “For the translation of the clinical study results into everyday medical practice, there is an urgent need for corresponding guidelines and recommendations for patients and doctors – especially in which constellations and target groups the use could be conceivable.”

Can the study be transferred to Germany?

Existing resistance could in any case make it difficult to transfer the American study results to Germany. “It is significant 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,” said Norbert Brockmeyer, chairman of the German STI Society .

In the EU, therefore, only a reduction in infections with chlamydia and syphilis can be expected. In addition, a significant change in the microbiome is to be expected, as well as increased side effects with longer use – such as undesirable effects on fertility and inflammatory reactions.

Georg Stary, who heads the “Translational Immunology in Mucosa and Skin (TIMS)” research group in Vienna, is also skeptical. It should be emphasized that the application cannot be generally recommended. “A recommendation would only make sense – if at all – for a selective group, and there, too, resistance is a problem that must be taken very seriously.”