Clinical comparison of antibiotic combinations in the treatment of peritonitis and related mixed aerobic‐anaerobic surgical sepsis

Patients with presumed mixed aerobic‐anaerobic peritoneal (126) or soft tissue (59) sepsis were treated with 1 of 3 randomly assigned antibiotic regimens: gentamicin plus clindamycin (68), gentamicin plus metronidazole (60), and cefamandole plus erythromycin (60). Primary and complicating foci of infection were cultured for both aerobic and anaerobic pathogens and antibiotic sensitivities were determined. In vitro aerobic and anaerobic sensitivities were, respectively: 80% and 70% for cefamandole, 10% and 64% for clindamycin, 31% and 91% for erythromycin, 83% and 0% for gentamicin, and 1% and 87% for metronidazole. Similar control of primary infection was obtained with each regimen (95%), although recurrence of sepsis was least common after treatment with gentamicin‐metronidazole (3%,p+<0.05) in contrast to gentamicin‐clindamycin (19%) and cefamandole‐erythromycin (15%). Significant complications were hypoprothrombinemia, occurring only after cefamandole‐erythromycin therapy (5%), and acute renal failure, found almost exclusively with gentamicin treatment (10%,p=< 0.01), and accounting for 3 deaths. Unremitting sepsis caused 3 deaths. There were 5 deaths due to complications not related to the mode of therapy. These results suggest the relative safety of cefamandole, superiority of metronidazole for anaerobes, and frequent life‐threatening nephrotoxicity of gentamicin.