Comparison of systemic prophylaxis with metronidazole-fosfomycin and metronidazole-cephalothin in elective colorectal surgery.

A comparative randomized study was designed to evaluate the prophylactic effect of two different combinations of antimicrobials, i.e. metronidazole-fosfomycin (n = 30) and metronidazole-cephalothin (n = 28), in elective colorectal surgery. The study was strictly consecutive and the treatment groups comparable. The total rate of surgical septic complications was low (10%) in both treatment groups. No anaerobic infections could be demonstrated and the clinical course was mild in all patients developing septic complications. No other antimicrobial therapy was given. Peroperative bacteriological sampling yielded aerobes and anaerobes in 51 and 32, respectively, of 58 patients. A high percentage of the isolated aerobes and anaerobes were cephalothin-resistant, whereas most aerobes were sensitive to fosfomycin. Only aerobes were isolated from surgical septic sites. The absence of anaerobic sepsis must be ascribed to the metronidazole prophylaxis; the probable reason for the low rate of surgical aerobic septic complications is that antimicrobials, active against aerobes, were included in the prophylactic regimens. The combination, metronidazole-fosfomycin, seems adequate and safe for continued evaluation.