Rise in antibiotic-resistant gonorrhea may be due to wide use of doxycycline for other STIs

Gonorrhea bacteria are becoming more resistant to the antibiotic doxycycline, potentially because the drug is taken after unprotected sex to preemptively lower the chance of contracting other sexually transmitted infections (STIs), according to a study.
A July 9 STAT News article featuring the study noted that the U.S. and several other countries have recommended that high-risk individuals, including men who have sex with men and transgender women who have had a bacterial STI in the prior year, take doxycycline after having unprotected sex to avoid getting infected with an STI. But the new study found that this practice—called doxy PEP (PEP is short for post-exposure prophylaxis)—appears to be playing a role in an increase in antibiotic resistance, particularly in gonorrhea infections.
Researchers reported on the study in a July 9 letter to the editor in the New England Journal of Medicine (NEJM). Senior author was Yonatan Grad, professor of immunology and infectious diseases at Harvard T.H. Chan School of Public Health. Postdoctoral fellow David Helekal was also a co-author.
In the study, researchers analyzed the genomic sequences of over 14,000 gonorrhea bacteria samples collected from U.S. patients between 2018-2024. They found that before 2020, under 10% of the sequences contained a gene that makes bacteria resistant to doxycycline. But by the first quarter of 2024, over 30% of the sequences contained the gene. The rise could have been driven by doxy PEP, according to Grad, because taking antibiotics leads to resistance not only in the targeted bacteria, but also in others that happen to be in the body.
However, Grad noted that the use of doxy PEP is likely to continue, since it is effective in preventing other STIs such as syphilis and chlamydia. “I think it’s a hard genie to put back in the bottle,” he said.
Read the STAT News article: Use of antibiotic to reduce STIs appears to be fueling some antibiotic resistance, research shows
Read the NEJM letter to the editor: Expansion of tetM-Carrying Neisseria gonorrhoeae in the United States, 2018–2024