Randomized study of minocycline + gentamicin compared with metronidazole + gentamicin for prophylaxis or treatment of mixed infections in abdominal surgery.

Seventy patients admitted for abdominal surgery requiring short-term perioperative prophylaxis were randomized to receive minocycline + gentamicin or metronidazole + gentamicin. Thirty patients were considered to be infected at the time of surgery and were treated with the same regimen. In the prophylactic cohort, one patient from each group developed postoperative fever. One patient receiving minocycline developed a wound infection. The overall infection rate was 2.6%. In the treatment cohort, it appeared that the patients receiving metronidazole had more severe underlying diseases than those receiving minocycline. Consequently, more postoperative non-infectious complications were observed in the former. Minocycline + gentamicin appeared at least as effective than metronidazole + gentamicin in preventing postoperative infectious complications associated with abdominal surgery or in treating intra-abdominal infections.