Antibiotic treatment during surgery for diffuse peritonitis: a prospective randomized study comparing the effects of cefuroxime and of a cefuroxime and metronidazole combination.

In a prospective randomized open study of patients operated upon for diffuse peritonitis, the effects of two different antibiotic regimens were evaluated. Cefuroxime given as a single drug (Group I; n = 59) was compared with a combination of cefuroxime and metronidazole (Group II; n = 63). Bacteriological cultures, both aerobic and anaerobic, were obtained peroperatively and in the event of any complication. The antibiotic sensitivities of isolated bacteria, and the serum and tissue concentrations of cefuroxime were determined. Postoperative infectious complications occurred in 22 per cent of Group I patients (cefuroxime), and in 17.5 per cent of Group II (cefuroxime plus metronidazole). The mortality rates were 5 per cent for Group I and 8 per cent for Group II. Tissue concentrations of cefuroxime were well above the MIC (minimal inhibiting concentration) values for most of the bacteria isolated. From a few patients in Group I, however, cultures were obtained with isolates sensitive to metronidazole but resistant to cefuroxime. Our findings suggest that, in the antibiotic treatment of patients operated for diffuse peritonitis, an agent which is primarily effective against aerobic bacteria (but not entirely without effect on anaerobes) is as effective as combination therapy covering both aerobic and anaerobic bacteria.