Effect of ceftibuten on the normal intestinal microflora

14 healthy volunteers were given 400 mg ceftibuten orally once daily for ten days. Stool specimens were collected before, during and after ceftibuten administration. Ceftibuten was well absorbed; on average 123 mg was excreted in urine 0-6 h after dosing, while only two volunteers had detectable concentrations of ceftibuten in faeces (< or = 3.2 mg/kg). There was an overgrowth of enterococci during the administration period, while the numbers of Escherichia coli and anaerobic cocci were reduced. Six volunteers were colonized by Clostridium difficile during days 4 to 17. Beta-lactamase activity was detected in faecal samples from eight volunteers and increased significantly during the administration period.