[Differentiating clinical characteristics in bacteriemia caused by Enterococcus faecalis or Enterococcus faecium]

Introduction: Enterococci are responsible for severe infections, such as endocarditis and bacteremia. During recent decades, enterococcal infections have grown in importance because of the increasing number of cases. Knowledge of the factors predisposing to acquisition of infection by E. faecalis or E. faecium may be useful to improve the empirical treatment.

Methods: Retrospective study of patients diagnosed with enterococcal bacteremia and hospitalized over a 7-year period (January 2000-December 2006), analyzing demographic data, clinical and microbiological characteristics, antibiotic exposure, treatment, and outcome. To identify the predisposing factors for isolation of E. faecalis or E. faecium in a clinical specimen, we performed univariate comparisons between the 2 groups, and subsequently, multivariate logistic regression analysis.

Results: A total of 228 episodes of bacteremia were recorded, 168 caused by E. faecalis and 60 by E. faecium. All E. faecalis isolates were susceptible to ampicillin, but only 25% of E. faecium were ampicillin-susceptible. There was only 1 vancomycin-resistant isolate. The variables independently associated with acquisition of E. faecium bacteriemia were surgical ward admission (odds ratio [OR], 4.223; P=.001), >5 days of previous treatment with cephalosporins (OR, 2.564; P=.013), >5 days of carbapenems (OR, 2.652; P=.027), previous administration of penicillins (OR, 2.008; P=0.044), SAPS score >30 at admission (OR, 3.530; P=0.001), and hepatobiliary disease as a comorbid condition (OR, 3.754; P<0.001),

Conclusion: Because of the differing susceptibility patterns of the enterococcal species studied, it is essential to know the factors predisposing to acquisition of infection by one or the other species to initiate adequate empirical treatment.