Antibiotic resistance is rising among MSM taking PrEP

Data from a study conducted among MSM using Pre-Exposure Prophylaxis (PrEP) to prevent HIV recorded an increased prevalence of mycoplasma genitalium (MG). However, the incidence rate did not change with the use of post-exposure prophylaxis (PEP) doxycycline. The results were presented by the Ipergay Agency for AIDS and Viral Hepatitis Research (ANRS Ipergay) in the journal Clinical Infectious Diseases.

Men participating in the ANRS Ipergay study use event-based oral PrEP containing tenofovir disoproxil fumarate and emtricitabine.

Participants in this prospective study were randomized into two groups:

• Group 1 (Doxy PEP) received 200 mg of doxycycline for 24 hours after each intercourse (up to 600 mg per week)
• Group 2 (No PEP) received no prophylactic treatment

210 men were tested for MG at baseline and again 6 months later. Swabs were collected from the oropharynx and/or anus. Resistance to azithromycin (AZM), fluoroquinolones (FQ) and doxycycline has also been investigated.

Of the 32 participants who tested positive for MG, 22 participants tested positive at baseline and 19 participants were positive at 6 months.

The overall prevalence for all sites at baseline was 10.5% (95% CI 6.7-15.4%), with the highest prevalence in urine at 6.3%, followed by anal samples at 4.3% and throat samples at 0.5%.

At 6 months, the overall prevalence was 9.9% (95% CI, 6.1-15.0%). Of the 19 participants who tested positive, 10 were in the doxycycline PEP group. The prevalence in the PEP group was 10.2% and in the non-PEP group it was 9.6% (P = 0.89).

Among the participants, 69.6% had mutations for azithromycin resistance and 11.1% for fluoroquinolones. Initially, 60% of the samples had mutations associated with resistance to AZM, and 5.6% had mutations associated with resistance to FQ. By 6 months they had increased to 73.3% and 13.3%, respectively.

The researchers concluded that the prevalence of MG in this cohort was high and that there was no evidence of a change in prevalence amongst those taking doxycycline PEP. In addition, they reported high levels of AZM and FQ resistance along with potential tetracycline resistance mutations.

According to the investigators, these results highlight the need for routine MG testing before treatment, and support recommendations for prevention, testing and treatment of asymptomatic MG infection.

Opinions of scientists about the use of antibiotics for pre-and-post-exposure prophylaxis of sexually transmitted infections differ. Some scientists believe that this will lead to the development of antibiotic resistance and reduce the effectiveness of drugs in treating STIs, while others believe that such prevention is possible where an infection can be prevented with a low probability of developing resistance.