The Centers for Disease Control and Prevention (CDC) is making a new recommendation for a preventive measure against bacterial sexually transmitted infections (STIs).
According to some experts, the measure—which proposes the use of the antibiotic doxycycline—could be a turning point in the fight against STIs, including gonorrhea, chlamydia, and syphilis.
The CDC published a notice on Oct. 2 seeking comment from physicians and public health officials on the proposed guidance for the drug as a preventive measure.
“The proposed guidelines for bacterial STI prevention include post-exposure prophylaxis with doxycycline (doxycycline PEP) because it has demonstrated benefit in reducing chlamydia, gonorrhea, and syphilis infections and represents a new approach to addressing STI prevention in populations at increased risk for these infections,” according to the CDC.
“Novel approaches are needed to address the STI epidemic, especially for populations disproportionately affected.”
Use of doxycycline as prophylaxis would also apply to sexual activity between men. Treatment would require a dose of 200 milligrams taken once within 72 hours after engaging in sexual activity—if one of the men involved had a history of a bacterial STI in the last year, or were deemed to be at a higher risk of contracting bacterial STIs.
Doxycycline was developed by Pfizer in the early 1960s. It has been used as prophylaxis against several infectious diseases, such as malaria and Lyme disease, while also being used as a treatment for acne. It also serves as the first-line treatment for chlamydia, and is also applied as an alternative treatment for syphilis in those who are allergic to treatment with the antibiotic penicillin.
Clinical studies have shown that doxycycline is highly effective in post-exposure prophylaxis (PEP) in men who have sex with men who tested negative for HIV. There were only minimal gastrointestinal side effects that subsided after treatment ended.
The rates of STIs are significantly higher in men who have sex with men. According to the CDC, repeated bacterial infections could also indicate an undiagnosed HIV infection.
“Doxycycline PEP, when offered, should be implemented in the context of a comprehensive sexual health approach including risk reduction counseling, STI screening and treatment, recommended vaccination, and linkage to HIV pre-exposure prophylaxis (PrEP), HIV care, or other services, as appropriate,” the CDC advisory states.
Nonmonogamous men who have sex with men have long been advised by the CDC to test regularly for STIs—typically at intervals of three to six months.
The use of doxycycline post-exposure prophylaxis (Doxy-PEP) has also been trialed in women. The results of a randomized trial, however, did not show any benefits, though this was partially due to the participants not taking the antibiotic as instructed.
Despite this, officials are saying that more information needs to be gathered in order to make broader assertions.
There is another reason for the prophylaxis being recommended, as widespread antibiotic use could lead to antibiotic resistance, which is a major global public health threat, according to the World Health Organization (WHO). Long-term data is not currently available on the prolonged use of doxycycline.
“Current data suggest overall benefit of the use of doxycycline PEP, but potential risks related to the development of resistance and impacts on the microbiome will need to be closely monitored after implementation of these guidelines,” according to the CDC.
Some local health departments, including the San Francisco Department of Public Health (SFDPH), have also previously recommended the use of Doxy-PEP as a prophylaxis against STIs.
An SFDPH study conducted in October last year corroborated the CDC’s findings, showing that the measure “significantly reduced acquisition of chlamydia, gonorrhea, and syphilis” in men who have sex with men.
The California Department of Public Health subsequently released similar guidance in April, recommending Doxy-PEP to men who have sex with men, and who have had at least one bacterial STI in the last 12 months.
The CDC will issue its final recommendations on November 16, when the proposed guidance comment period on doxycycline expires.
