Risk factors for multidrug-resistant bacteria in patients with post-operative peritonitis requiring intensive care

Abstract

This prospective non-interventional study investigated the risk factors for multidrug-resistant bacteria (MDRB) in patients with post-operative peritonitis (POP), to provide guidance for empirical antimicrobial therapy. All consecutive patients, >15 years old, admitted to a surgical intensive care unit (ICU) between September 2006 and January 2009 for a first episode of POP were included. Antibiotic susceptibilities of microorganisms recovered from blood cultures and peritoneal fluid were determined by disc diffusion. Amoxicillin/clavulanic acid, ticarcillin/clavulanic acid, piperacillin/tazobactam, cefotaxime, ceftazidime, cefepime, imipenem, gentamicin, amikacin and ciprofloxacin were tested against Gram-negative bacteria, and oxacillin, amoxicillin, vancomycin, gentamicin and erythromycin were tested against aerobic Gram-positive bacteria. Results were reported as susceptible or resistant. MDRB were isolated from 20/115 (17%) patients. In univariate analysis, use of antimicrobial therapy during the 3 months prior to hospitalization and a long duration between hospital admission or first operation and relaparotomy were significantly associated with MDRB recovery. In multivariate analysis, only antimicrobial treatment in the 3 months preceding hospitalization and duration between first operation and relaparotomy were independent risk factors for MDRB [odds ratio (OR) = 5.80, 95% confidence interval (95% CI) = 1.99−16.91 and OR = 1.10, 95% CI = 1.02−1.19, respectively]. No MDRB were found when the delay between the first operation and relaparotomy was 5 days between the first operation and relaparotomy.