Antibiotics can cause long-term changes in the bacterial population of the human gut

Using a sophisticated novel technique, scientists at the Marine Biological Laboratory at the Josephine Bay Paul Center in Massachusetts, have completed the most precise survey to date of how microbial communities in the human gut respond to antibiotic treatment.

Using very conservative criteria, the scientists identified at least 3,300 to 5,700 genetically distinct types of bacteria in the human distal gut, and antibiotic treatment influenced the abundance of about a third of them. Antibiotic treatment caused shifts in the structure of the microbial community. Some bacteria that were in low abundance prior to treatment became more abundant, and bacteria that were dominant decreased in abundance. Some of these shifts can be persistent; some individuals may recover quickly, and others won't recover for many months.

In all the individuals tested in the study, the bacterial community recovered and closely resembled its pre-treatment state within four weeks after the antibiotic course ended, although several types of bacteria failed to recover within six months.

This raises questions about the health effects of the changes to the bacterial population of the gut which may occur with antibiotic treatment. Previous studies have related changes in the bacterial population of the gut to cancer and obesity so changes in this population could have important, but as yet undiscovered, health effects.

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Nov 18 issue of PloS Biology

First published in April 2009


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