Successful substitution of rectal metronidazole administration for intravenous use.

Wound infection and isolation of anaerobic organisms before and after intravenous and rectal administration of metronidazole were studied in 24 505 surgical patients. In the 6303 patients who underwent "risk" surgery (bowel, biliary, gynaecological, or otolaryngological surgery) introduction of intravenous metronidazole was associated with a striking fall in wound infection and wound anaerobe isolation rates; and the changes were maintained when the majority of metronidazole used was in suppository form. In the 18 202 patients who underwent "clean" surgery (e.g., orthopaedic, ophthalmic, and plastic surgery) metronidazole use was associated with a small formulation-independent change in infection rate without change in anaerobe isolation rates. Without compromising clinical care the use of intravenous metronidazole can be limited to a minority of patients with special needs.