Single Course of Antibiotics Disrupts Gut Microbiome for 1 Year

Authors of a new study have found that just a single course of antibiotics has the strength to disrupt gut microorganisms for as long as 1 year, and recommend that physicians use antibiotics only when necessary.

A team led by Egija Zaura, MD, an associate professor in oral microbial ecology at the Academic Centre for Dentistry in Amsterdam, the Netherlands, studied 66 healthy adults from the United Kingdom and Sweden who were prescribed different antibiotics. Those taking part in the study were randomly assigned to receive a full course of 1 of 4 antibiotics: amoxicillin or minocycline, ciprofloxacin, clindamycin, or a placebo. Zaura and colleagues collected fecal and saliva samples from patients at the start of the study, immediately after participants took the antibiotics. The authors collected fecal and saliva samples again at 1, 2, 4, and 12 months after participants finished the course.
______________________________________________________________________________________________________________________________________________________________________

RELATED CONTENT
Certain Gut Bacteria Can Block Food Allergies
Study: Gut Bacteria May Boost Metabolic Health
______________________________________________________________________________________________________________________________________________________________________

The researchers found the drugs enriched genes associated with antibiotic resistance, and significantly affected microbial diversity in the gut for several months after exposure. Conversely, the authors saw signs of recovery in microorganisms within the saliva in just a few weeks. In addition, microbiome diversity in feces was greatly reduced for as long as 4 months in patients taking clindamycin, and as much as 12 months in participants who took ciprofloxacin. However, oral cavity microbiome diversity was only changed for up to 1 week after exposure. While amoxicillin was linked to the highest number of antibiotic-resistant genes, the drug showed no considerable effect on microbiome diversity in either the gut or oral cavity.

Ultimately, the findings show that antibiotics “have an enormous impact on gut microbiome,” says Zaura, who thus recommends that antibiotics be used “only when really necessary.”

—Mark McGraw

Reference

Zaura E, Brandt B, et al. Same Exposure but Two Radically Different Responses to Antibiotics: Resilience of the Salivary Microbiome versus Long-Term Microbial Shifts in Feces. mBio. 2015.