Report: Gut flora difficult to restore post-antibiotics

ANN ARBOR, Mich. Infection and Immunity, suggesting that those consumers taking a probiotic in conjunction with antibiotic therapy may need to continue with a probiotic supplement for some time following the course of antibiotics.—Patients on a course of antibiotics may have disrupted gut flora for weeks after stopping the medication, according to a report in the June issue of

In studies in mice, University of Michigan scientists determined that two different types of antibiotics can cause moderate- to wide-ranging changes in the ranks of beneficial bacteria. In the case of one of the antibiotics, good bacteria did not recover its former diversity even many weeks after a course of antibiotics was over.

The study results suggested that unless medical research discovers how to protect or revitalize the gut microbial community, “we may be doing long-term damage,” said Vincent Young, assistant professor in the departments of internal medicine and microbiology and immunology at the University of Michigan Medical School, and senior author of the study. “Both antibiotic treatments caused significant changes in the gut microbial community. However, in mice given cefoperazone, there was no recovery of normal diversity. In other mice given an amoxicillin-containing combination, the microbiota largely recovered, but not completely,” Young said.

Although cefoperazone is not commonly used in the United States, such related drugs as cefoxitin are, Young said. The study findings suggested that it is very important to use antibiotics only when indicated, especially in people with health problems that might already compromise their gut microbe health. Multiple rounds of antibiotics also may deserve concern.

The findings could eventually lead to better choices of antibiotics to minimize side effects of diarrhea, especially in vulnerable patients. They could also aid in understanding and treating inflammatory bowel disease, which affects an estimated 500,000 to 1 million people, and Clostridium difficile, a growing and serious infection problem for hospitals.