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Taking antibiotics can change your gut bacteria for months

taking antibiotics can change your gut bacteria

Antibiotics are beneficial in many cases, but taking them too often may be leading us down a harmful path. In addition to contributing to widespread antibiotic resistance, one study led by the University of Amsterdam finds another reason for doctors and patients alike to use discretion when it comes to starting antibiotics.

Specifically, researchers found that just a weeklong course of antibiotic treatment can lead to dramatic changes in the bacterial population of the human gut—and those changes can last up to a full year after taking the medication.

More than 60 adults took part in the study and received either a placebo or a course of one of four common antibiotics: clindamycin, ciprofloxacin, minocycline, or amoxicillin. Samples of both oral and gut bacteria were taken before and after the study, and follow-up samples were taken throughout the year. While the oral bacteria population seemed to recover quickly, the gut was another story.

Among the most notable results was an increase in the number of antibiotic-resistant genes present in the gut microbiome for all groups. Additionally, participants in the clindamycin and ciprofloxacin group saw a notable decline in certain types of beneficial bacteria associated with reduced oxidative stress and a healthy inflammatory response, leaving researchers concerned about the potential effects of a decrease in gut diversity.

According to the study findings, published in mBio, “…even a single antibiotic treatment in healthy individuals contributes to the risk of resistance development and leads to long-lasting detrimental shifts in the gut microbiome.” The reality is that antibiotics don’t discriminate; they kill a lot of good bacteria along with the bad, and those good bacteria make up most of our natural defenses. (Remember, at least 70% of our immune system is in the gut.)