Antibiotic-resistant microorganisms in patients with bloodstream infection of intraabdominal origin: risk factors and impact on mortality

Background Knowledge of resistance patterns is essential to choose empirical treatment. We aimed to determine the risk factors for antibiotic-resistant microorganisms (ARM) in intraabdominal infections (IAI) and their impact on mortality. Methods Retrospective cohort study of patients with bacteremia from IAI origin in a single hospital between January 2006 and July 2017. Results A total of 1485 episodes were recorded, including 381 (25.6%) due to ARM. Independent predictors of ARM were cirrhosis (OR 2; [95% CI 1.15–3.48]), immunosuppression (OR 1.49; 1.12–1.97), prior ceftazidime exposure (OR 3.7; 1.14–11.9), number of prior antibiotics (OR 2.33; 1.61–3.35 for 1 antibiotic), biliary manipulation (OR 1.53; 1.02–2.96), hospital-acquisition (OR 2.77; 1.89–4) and shock (OR 1.48; 1.07–2). Mortality rate of the whole cohort was 11.1%. Age (OR 1.03; 1.01–1.04), cirrhosis (OR 2.32; 1.07–4.38), urinary catheter (OR 1.99; 1.17–3.38), ultimately (OR 2.28; 1.47–3.51) or rapidly (OR 13.3; 7.12–24.9) fatal underlying disease, nosocomial infection (OR 2.76; 1.6–4.75), peritonitis (OR 1.95, 1.1–3.45), absence of fever (OR 2.17; 1.25–3.77), shock (OR 5.96; 3.89–9.13), and an ARM in non-biliary infections (OR 2.14; 1.19–3.83) were independent predictors of 30-day mortality. Source control (OR 0.24; 0.13–0.44) and 2015–2017 period (OR 0.29; 0.14–0.6) were protective. Conclusion Biliary manipulation and septic shock are predictors of ARM. The presence of an ARM from a non-biliary focus is a poor-prognosis indicator. Source control continues to be of paramount importance.