Presumptive antibiotics for penetrating abdominal wounds

The optimal antibiotic agent or agents for penetrating abdominal injuries remains undetermined. During the two year period ending April 1985, 150 consecutive patients undergoing celiotomy for penetrating abdominal trauma were prospectively randomized to receive either mezlocillin (4 grams every six hours) or clindamycin (600 milligrams every six hours) and gentamicin (loading dose of 2.0 milligrams per kilogram, then 1.5 milligrams per kilogram every eight hours). Antibiotics were begun in the emergency department with duration of coverage based upon the injury pattern--colon, five days; other hollow visceral injury, two days, and all others, one day. Ten patients were excluded due to breach in protocol and other patients died within 48 hours of presentation. The two study groups, comprised of the remaining 130 patients, were comparable with respect to age, sex, injury mechanism, incidence of colonic injuries, intraoperative blood replacement and abdominal trauma index. Overall incidence of septic morbidity was similar among the groups; ten of the 61 patients receiving mezlocillin and nine of those receiving clindamycin and gentamicin had infection develop. There was no significant difference with respect to extensive abdominal infection (10 versus 3 per cent). The pattern of postoperative infection and offending pathogens were similar in the study groups. Enterobacteriaceae, enterococcus and Bacteroides species were most frequently isolated. Infection was due to an organism resistant to the initial study regimen in one of the ten failures with mezlocillin and in two of the nine failures with clindamycin and gentamicin. Mezlocillin, a single agent broad spectrum penicillin, achieved comparable results with more expensive potentially toxic combination therapy for penetrating wounds.