Impact of imipenem/cilastatin therapy on faecal flora

To evaluate the effects of parenteral imipenem/cilastatin therapy upon human faecal microflora, stool specimens obtained from ten patients before, during and after therapy were cultured quantitatively for aerobic and anaerobic microorganisms. The patients received 500 mg imipenem combined with 500 mg cilastatin every 6 h for 6-11 days. The antimicrobial therapy was associated with a small decrease in the numbers of enterobacteria, anaerobic cocci and bacteroides during treatment but afterward the microflora normalized in all patients. None of the patients was colonized with new imipenem-resistant bacteria, had Clostridium difficile or cytotoxin in the stools, or developed diarrhoea.