Antibiotic therapy for abdominal infection.

Abdominal infections are treated by resuscitation, abdominal drainage, control of the source of infection, and antimicrobial agents. Ideally, antimicrobial therapy is active against expected pathogens, safe and effective in clinical trials, inexpensive, and unlikely to promote drug resistance. Numerous single-agent and combination-drug regimens have been efficacious in clinical trials, based on coverage of Escherichia coli and Bacteroides species, the predominant pathogens isolated. Whether expanded antimicrobial coverage is required, especially in hospital-acquired infections, is controversial. Candida infections should be treated with antifungal therapy in patients with recurrent abdominal infections, immunosuppressed patients, and those with candidal abscesses. Most agents have few serious adverse effects; aminoglycosides are the least expensive agents but cause nephro- and ototoxicity. There is little information on the promotion of drug resistance in this condition. Recent developments include the introduction of ticarcillin/clavulanic acid, ampicillin/ sulbactam, piperacillin/tazobactam, meropenem, aztreonam/clindamycin, and ciprofloxacin/metronidazole; success with once-daily aminoglycosides; evidence that antibiotics limit infectious complications of pancreatitis; controversy over the value of diagnostic cultures; the use of oral therapy; evidence in favor of shorter courses of treatment; and the introduction of pharmacoeconomic studies. Clinical investigators are challenged to improve drug trials by stratifying and controlling for the adequacy of surgical intervention.