Risk factors and outcomes of endocarditis due to non-HACEK Gram-negative bacilli: data from the prospective multicenter SEI cohort

Objective: To investigate predisposing factors and outcomes of non-HACEK Gram-negative bacilli (GNB) infective endocarditis (IE) in a multicenter, contemporary cohort.Patients and Methods:Patients with IE due to GNB prospectively observed in 26 Italian centers from 2004 to 2011 were analyzed. Using a case-control design, each case was compared to three controls with IE by other etiologies matched for age and sex. Logistic regression was performed to identify risk factors for GNB IE. Factors associated with early and late mortality were assessed by Cox regression analysis.Results:The study group comprised 58 patients with GNB IE.Escherichia coliwas the most common pathogen followed byPseudomonas aeruginosaandKlebsiella pneumoniaeGenitourinary tract as source of infection (OR 13.59, 95% CI 4.63-39.93, p<.001), immunosuppression (OR 5.16, 95% CI 1.60-16.24, p=.006) and presence of a cardiac implantable electronic device (CIED) (OR 3.57, 95% CI 1.55-8.20, p=.003) were factors independently associated with GNB IE. The in-hospital mortality was 13.8%, and rose up to 30.6% at 1 year. A multidrug-resistant etiology was associated with in-hospital (HR 21.849, 95% CI 2.672-178.683, p=0.004) and 1-year mortality (HR 4.408, 95% CI 1.581-12.287, p=0.005).Conclusions:The presence of a genitourinary focus, immunosuppressive therapy and an indwelling CIED are factors associated with GNB IE. MDR etiology is the major determinant of in-hospital and long-term mortality.