Effect of meropenem on the intestinal microflora.

Ten healthy volunteers were given 500 mg of meropenem by intravenous infusion over 30 min three times daily for seven days. Stool specimens were collected before, during and after meropenem administration. The numbers of enterobacteria and streptococci decreased during the administration period, while the numbers of enterococci increased. There was a decrease in the numbers of clostridia, bacteroides and gram-negative cocci, while the numbers of gram-positive cocci and rods were not changed by the administration of meropenem. The intestinal flora returned to normal in all volunteers within two weeks after the termination of meropenem administration.