Management of complicated intra-abdominal infections

Complicated intra-abdominal infections are defined by the U.S. Food and Drug Administration as those in which an operation would not remove all of the infected tissue. Therefore perforated appendicitis, although usually straightforward to treat, would be considered complicated, whereas gangrenous non-perforated appendicitis would not. Antibiotics play an adjunctive role to the surgical procedure in the management of these infections. Studies of newer antibiotics generally exclude critically ill patients, so it is unclear whether dose or duration of therapy can be addressed by such studies. Typical characteristics of anti-infective studies of intra-abdominal infection are: enrollment of upwards of 50% appendicitis cases, mortality 5%, and a clinical cure rate of 85%. Several antibiotic combinations with metronidazole are acceptable (e.g. third- or fourth-generation cephalosporin, aminoglycoside, aztreonam, or second-generation quinolone), as are several agents as monotherapy (e.g. second-generation cephalosporin, beta-lactamase agent, or third-generation quinolone). In addition to questions of dose and duration, questions have been raised regarding the value of intraoperative cultures, and whether issues of the quality of the surgical procedure can be addressed. The issue of the adequacy of surgical "source control" may be paramount, as an improper, untimely, or incorrect operation would have an overwhelmingly negative effect on outcome compared to the efficacy of the antibiotic.