Presumptive antibiotics for penetrating abdominal wounds.

The optimal antimicrobial agent or agents for penetrating abdominal injuries remains undetermined. During the three year period ending August 1987, 317 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 kilograms every eight hours. Antibiotics were begun in the emergency department with duration of coverage based on the pattern of injury: the colon, five days; other hollow visceral injury, two days, and all others, one day. Twenty-three patients were excluded because of breach of protocol and 16 others died within 72 hours of presentation. The two study groups, 136 patients receiving mezlocillin and 142 patients receiving gentamicin and clindamycin, were comparable with respect to age, sex, mechanism of injury, shock, intraoperative replacement of blood, abdominal trauma index and distribution of hollow visceral injuries. The over-all incidence of septic morbidity was similar: infections developed in 21 (15 per cent) of the patients receiving mezlocillin compared with 19 (13 per cent) of patients receiving gentamicin and clindamycin. There was no significant difference in major infections (lobar pneumonia and intra-abdominal abscess), with 13 per cent in each group. The offending pathogens were similar. The most common isolates in intra-abdominal abscess were Escherichia coli, Klebsiella and Enterococcus species and anaerobic Bacteroides species. Mezlocillin, an extended spectrum penicillin, achieved similar results, compared with the expensive and potentially toxic combination regimen in patients with penetrating abdominal injuries.