Study: Common Antibiotic Significantly Reduces STI Transmission

A new study confirms that taking doxycycline within 72 hours can significantly reduce the risk of getting an STI from condomless sex according tyo a relesse from the National Institutes of Health.

A study published in the New England Journal of Medicine on April 6 looked at the effectiveness of using doxycycline – a readily available oral antibiotic – as a "morning after" preventative among men who have sex with men (MSM) and transgender women, the release noted.

"Specifically, the post-exposure approach, termed doxy-PEP, resulted in a two-thirds reduction in the incidence of syphilis, gonorrhea, and chlamydia among the study participants, all of whom reported having an STI within the previous year," the NIH release detailed.

"STI incidence has been increasing in the United States over the past few years with a disproportionate impact among MSM and transgender women," the release explained.

"An estimated 2.5 million cases of syphilis, gonorrhea, and chlamydia occurred in 2021 up from 2.4 million cases in 2020, according to the Centers for Disease Control and Prevention. If left untreated, STIs can lead to serious health consequences, including brain and nerve problems, blindness, infertility and increased risk of HIV acquisition."

Dr. Hugh Auchincloss, the acting director of the National Institute of Allergy and Infectious Diseases (NIAID), spoke to the relevance of the study's findings, saying, ""Effective methods for preventing sexually transmitted infections are badly needed.

"This is an encouraging finding that could help reduce the number of sexually transmitted infections in populations most at-risk," Dr. Auchincloss added.

Dr. Annie Luetkemeyer, one of the study's co-principal investigators, said: "Given its demonstrated efficacy in several trials, doxy-PEP should be considered as part of a sexual health package for men who have sex with men and transwomen if they have an increased risk of STIs."

Because infectious diseases can develop resistance to antibiotics over time, Dr. Luetkemeyer added, "It will be important to monitor the impact of doxy-PEP on antimicrobial resistance patterns over time and weigh this against the demonstrated benefit of reduced STIs and associated decreased antibiotic use for STI treatment in men at elevated risk for recurrent STIs."

The New York Times reported on the news last month, in advance of the study's publication.

"The Centers for Disease Control and Prevention does not yet recommend post-exposure doxycycline to prevent S.T.I.s," the Times noted. "But based on the strength of the new evidence, some cities like San Francisco are already offering the antibiotic to those at high risk of infection with chlamydia, syphilis and gonorrhea. Health officials are calling it 'doxy-PEP.' "

Rates of syphilis and gonorrhea have rebounded over the last two decades, the Times said, recalling that at the turn of the millennium, syphilis "was nearly eliminated in the United States" – but the account went on to add, "the infections have resurged, in large part because of the shuttering of sexual health clinics across the country."

Rates of transmission have increased dramatically in recent years. "Between 2017 and 2021, syphilis cases shot up by 68 percent and gonorrhea cases by 25 percent," the Times article detailed. "About half of those new infections were in teens and young adults.

"The incidence of S.T.I.s also rose in women, and Black women in particular," the article noted. "Rates of congenital syphilis, acquired during gestation from an infected mother, increased by nearly 200 percent during the period."

The Times also noted that "Although these studies included only men who have sex with men, she and other researchers said they expected the results to be applicable to men of any sexual orientation.

"But the antibiotic did not prevent S.T.I.s in cisgender women, at least in Kenya," the Times cautioned.