Enterococci increase the morbidity and mortality associated with severe intra-abdominal infections in elderly patients hospitalized in the intensive care unit

Objectives: Enterococci may increase morbidity and mortality in elderly patients with intra-abdominal infections (IAIs) hospitalized in the intensive care unit (ICU). Patients and methods: A single-centre, retrospective evaluation of an ICU database (1997-2007) of elderly ICU patients (>= 75 years) with a severe IAI was performed. Demographics, severity scores, underlying diseases, microbiology and outcomes were recorded. Patients with enterococci isolated in peritoneal fluid (E+ group) were compared with those lacking enterococci in peritoneal fluid (E- group). Stepwise multivariate logistic regression was used to identify independent factors associated with mortality. Results: One hundred and sixty patients were included (mean +/- SD age 82 +/- 5 years; n=72 in the E+ group). The E+ group was more severely ill than the E- group, with higher Simplified Acute Physiologic Score 2 (61 +/- 20 versus 48 +/- 16, P=0.0001) and Sequential Organ Failure Assessment scores (8 +/- 3 versus 5 +/- 3, P=0.0001), a greater postoperative infection rate (58.3% versus 34.1%, P=0.01), a higher incidence of inappropriate empirical antimicrobial therapies (33.3% versus 19.3%, P=0.04), a longer duration of mechanical ventilation (11.8 +/- 10.9 versus 7.8 +/- 10.2 days, P=0.02) and greater vasopressor use (7.2 +/- 7.1 versus 3.3 +/- 4.1 days, P=0.001). ICU mortality was higher in the E+ group than in the E- group (54.2% versus 38.6%, P=0.05). In the multivariate analysis, E+ status was independently associated with mortality (odds ratio 2.24; 95% confidence interval 1.06-4.75; P=0.03). Conclusions: In severely ill, elderly patients in the ICU for an IAI, the isolation of enterococci was associated with increased disease severity and morbidity and was an independent risk factor for mortality.