2023-08-11 11:25:18
An antibiotic developed decades ago could turn into a preventive pill across the Atlantic. The United States should soon recommend the addition of a new weapon to the arsenal used against sexually transmitted infections. Doxycycline, when taken after sex without a condom, has been shown in clinical trials to significantly reduce the risk of infection with three diseases: chlamydia, gonorrhea and syphilis.
The main US federal health agency, the CDC (Centers for Disease Control and Prevention), is responsible for making a decision on new recommendations. It will have to take into account the need to contain epidemics affecting millions of Americans, but also the risk of increasing resistance to the antibiotic.
Priority groups at risk
“Innovation and creativity are important in public health, and we desperately need new tools,” said CDC official Jonathan Mermin. These recommendations, which should be published this summer, will probably only target the groups most at risk: gay men or transgender women with previous infections.
But as word spreads, some doctors are already prescribing the antibiotic for this purpose. Malik, a 37-year-old Washington resident who did not want to give his last name, has already used doxycycline twice as a preventive measure, on the advice of his doctor, after risky reports – including one with a partner not having informed that he had withdrawn his condom.
From -80 to -50% infections
Cases of these three bacterial infections have been increasing for a decade and reached 2.5 million in 2021 in the United States. Firstly because mechanically, the more infections there are, the more they are transmitted. But also because condoms are used less and less since the arrival of Prep – a drug taken as a preventive measure to avoid contracting AIDS.
Additionally, people on Prep should get tested every three months, which helps identify more infections. Doxycycline has been shown to be effective in three out of four clinical trials conducted. “We found a two-thirds reduction in sexually transmitted infections,” said Annie Luetkemeyer, who led a US trial. The latter was carried out on 500 men having sex with other transgender men and women. Efficacy was found to be higher against chlamydia and syphilis (-80% infections) than for gonorrhea (-55%).
Potential antibiotic resistance
Side effects were few. But expanding access to doxycycline has also raised concerns that antibiotic resistance could develop, especially for gonorrhea, where the bacteria mutate rapidly. Initial analyzes are however reassuring. During the American clinical trial, the researchers compared samples of this bacterium from infections that occurred despite treatment with doxycycline, with samples from the untreated group.
The rate of resistant bacteria was certainly higher for the treated group, but that could simply mean that the antibiotic is less effective against this resistant strain, not that it caused it, explained Connie Celum, co-leader of this work. . Moreover, since doxycycline could reduce the number of infections by half, it would mean half as many people to treat with the antibiotic normally prescribed for gonorrhea (ceftriaxone). But doctors want to preserve the effectiveness of this drug.
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