Effect of inappropriate initial empiric antibiotic therapy on outcome of patients with community-acquired intra-abdominal infections requiring surgery.

To assess the significance of initial empiric parenteral antibiotic therapy in patients requiring surgery for community-acquired secondary peritonitis, 425 patients hospitalized between January 1999 and September 2001 in 20 clinics across Germany were followed for a total of 6,521 patient days. Perforated appendix (38%), colon (27%), or gastroduodenum (22%) were the most common sites of infection. Escherichia coli was the most common pathogen. A total of 54 (13%) patients received inappropriate initial parenteral therapy not covering all bacteria isolated, or not covering both aerobes and anaerobes in the absence of culture results. Clinical success, predefined as the infection resolving with initial or step-down therapy after primary surgery, was achieved in 322 patients (75.7%; 95% confidence interval (CI), 70.6-81.2). Patients were more likely to have clinical success if initial antibiotic therapy was appropriate (78.6%; 95% CI, 73.6-83.9) rather than inappropriate (53.4%; 95% CI, 41.1-69.3). Patients having clinical success were estimated to stay 13.9 days in hospital (95% CI, 13.1-14.7), while those who had clinical failure stayed 19.8 days (95% CI, 17.3-22.3). In conclusion, appropriateness of initial parenteral antibiotic therapy was a predictor of clinical success, which in turn was associated with length of stay.