Metronidazole in the prevention and treatment of anaerobic sepsis

Clinical trials were carried out in order to determine the value of metronidazole in preventing the development of anaerobic infections after surgery. Following a successful controlled trial of hysterectomy patients, among whom the prophylactic use of oral metronidazole resulted in a reduction of the anaerobic sepsis rate from 25% to nil, further trials were carried out with patients having urgent appendicectomy, those having elective colonic surgery and pregnant women having delivery by the vaginal and caesarean routes. These studies were conducted as double-blind trials in which metronidazole was compared with a placebo; patients were randomly allocated to the two "drug" groups. Since completion of the hysterectomy trial over 618 hysterectomies have been performed under metronidazole cover, none of which were complicated by anaerobic sepsis. Among appendicectomy patients, anaerobic infection did not develop in any of the 49 patients who received prophylactic metronidazole, but bacteriologically confirmed clinical anaerobic infections developed in 9 (19%) of 46 control patients. Since completion of the trial over 1098 appendectomies have been performed under metronidazole cover, only two of which developed an anaerobic infection. Among colonic surgery patients, anaerobic infections did not develop in any of 27 patients who received prophylactic metronidazole, but bacteriologically confirmed clinical anaerobic infections developed in 11 (58%) of 19 control patients. Since completion of the trial over 126 colonic operations have been performed under metronidazole cover, none of which were complicated by anaerobic sepsis. Pregnant women having vaginal delivery were not especially prone to anaerobic infections so that metronidazole prophylaxis is not indicated in these patients. Delivery by caesarean section appears to carry a risk of post surgical anaerobic sepsis in about 20% of patients not protected with metronidazole prophylaxis. Metronidazole is regarded as the drug of choice for the treatment of those non-clostridial anaerobic infections that require antimicrobial therapy. It may be given orally, rectally, intravenously and topically, has virtually no side effects and its use is characterized by a strikingly rapid and sustained clinical and microbiological response.