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Taking a dose of the oral antibiotic doxycycline after a high-risk sexual encounter has dramatically decreased the incidence of sexually transmitted infections (STIs) in locations the place the technique is being tried.
Regardless of its effectiveness, the brand new technique, referred to as doxy-PEP, might include dangers, particularly with power use. Consultants fear in regards to the influence on the neighborhood of intestine micro organism, often known as the microbiome, and the potential that the antibiotic will give rise to resistant strains of micro organism.
Now, utilizing metagenomic sequencing to see the influence of doxycycline on the intestine microbiome of those that took it incessantly for six months, UC San Francisco researchers have discovered each reassurance and doable trigger for concern.
Doxy-PEP didn’t have a lot influence on the general composition of bacterial communities in gastrointestinal tracts. However scientists famous indicators of resistance constructing towards tetracycline, the category of antibiotic that doxycycline belongs to, which might make it much less efficient.
The examine seems Oct. 3 within the journal Nature Medication.
Whereas doxy-PEP didn’t seem to have international impacts on the intestine microbiome, it did have impacts on the antimicrobial resistance of intestine micro organism, each when it comes to the proportion of tetracycline class resistance genes and the quantity that had been turned on, or expressed.»
Chaz Langelier, Affiliate Professor, Medication, Division of Infectious Ailments, College of California – San Francisco
San Francisco’s high-profile STI prevention position
Doxy-PEP is brief for doxycycline post-exposure prophylaxis, and it entails taking two 100-milligram tablets inside 72 hours of condomless intercourse.
Prompted by early promising scientific trial outcomes, San Francisco grew to become the primary metropolis within the nation in October of 2022 to advocate doxy-PEP to homosexual and bisexual males and transgender girls with a historical past of getting unprotected encounters with a number of companions.
In March of 2024, the San Francisco Division of Public Well being launched outcomes displaying that after a few yr, the strategy halved the incidence of chlamydia and early syphilis. In June, the U.S. Facilities for Illness Management and Prevention (CDC) issued tips recommending doxy-PEP for these teams. It was the primary new STI prevention instrument to be adopted in many years.
However the widespread use of antibiotics raises considerations about resistance and the potential dangerous influence on intestine well being, particularly the steadiness of micro organism and different microbes. Disruption can result in diarrhea, nausea, fever and belly ache; and till now, there had been very restricted analysis into these uncomfortable side effects.
Working with the Chan Zuckerberg Biohub and scientists in Washington and Georgia, UCSF researchers studied individuals from the current doxy-PEP scientific trial in San Francisco and Seattle, led by Annie Luetkemeyer, MD, a professor of drugs within the Division of Infectious Ailments at UCSF.
The examine included 100 people who used doxy-PEP and 50 people who acquired standard-of-care and didn’t use doxy-PEP. Researchers analyzed rectal swabs collected at enrollment and after six months to review the presence of DNA and RNA from intestine micro organism and their antibiotic resistance genes.
«Whereas we discovered no main modifications to the neighborhood of intestine micro organism in doxy-PEP customers, we noticed that doxy-PEP customers over time had rising quantities of tetracycline resistance genes current of their intestine,» mentioned Victoria T. Chu, MD, MPH, an assistant professor of pediatrics within the Division of World Well being and Infectious Ailments at UCSF and a primary writer of the examine. «It additionally gave the impression to be dose dependent, that means the extra doxy-PEP they used, the bigger the rise was.»
Extra analysis is required to find out which intestine micro organism are turning on these tetracycline-resistant genes to know whether or not it will result in extra doxycycline-resistant infections amongst each people taking doxy-PEP and within the larger neighborhood.
«Proper now, it appears like the professionals outweigh the cons,» Langelier mentioned. «Particularly given the dramatic rise in STIs, specifically syphilis, over the previous decade.»
Supply:
Journal reference:
Chu, V. T., et al. (2024). Impression of doxycycline post-exposure prophylaxis for sexually transmitted infections on the intestine microbiome and antimicrobial resistome. Nature Medication. doi.org/10.1038/s41591-024-03274-2.
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