MANAGEMENT OF INTRAABDOMINAL INFECTIONS - THE CASE FOR INTRAOPERATIVECULTURES AND COMPREHENSIVE BROAD-SPECTRUM ANTIBIOTIC COVERAGE

Objective: To test the hypothesis that comprehensive broad-spectrum em pirical antimicrobial therapy is superior to limited-spectrum empirica l antimicrobial therapy in intra-abdominal infections. Design: Prospec tive, randomized, double-blinded study. Setting: University-affiliated hospitals in Canada. Patients: Two hundred thirteen patients with int raabdominal infections and planned operative or percutaneous drainage. Intervention: limited-spectrum empirical antimicrobial therapy c cons isted of cefoxitin sodium, 2 g, intravenously, every 6 hours (n=109). Comprehensive broad-spectrum empirical antimicrobial therapy consisted of a combination of imipenem and cilastatin sodium, 500 mg, intraveno usly, every 6 hours (n=104). Main Outcome Measures: Failure to cure th e intraabdominal infection (persistence of infection or death). Result s: Of initial isolates, 98% were sensitive to imipenem plus cilastin s odium compared with 72% for cefoxitin. No difference was found in the failure rate between treatment groups. Among various reasons for failu re (including technical), 12 of 80 patients in the limited-spectrum em pirical antimicrobial therapy group had resistant organisms at a secon d intervention compared with 1 of 74 in the comprehensive broad-spectr um empirical antimicrobial therapy group (P<.003, chi(2)). One death i n the limited-spectrum empirical antimicrobial therapy group was due t o autopsy-proved disseminated Pseudomonas aeruginosa (blood, peritoneu m, lung, and pleural fluid) that was resistant to cefoxitin, and the o ther was associated with peritonitis due to cefoxitin-resistant Entero bacter cloacae. One death in the comprehensive broad-spectrum empirica l antimicrobial therapy group was associated with peritonitis from Clo stridium perfringens that was sensitive to imipenem plus cilastin sodi um, and the other was associated with peritonitis from Pseudomonas aer uginosa that was resistant to imipenem plus cilastin sodium. Conclusio n: Treatment failure of intra-abdominal infection may be due, in part, to the presence of resistant pathogens at the site of infection. Ther efore, routine culture of these sites seems worthwhile and empirical t herapy should be as comprehensive as possible and should cover all pot ential pathogens.