Enterococcus avium bacteremia: a 12-year clinical experience with 53 patients

Because Enterococcus avium is rarely isolated from blood cultures, little is known about the clinical features and outcomes of bacteremia caused by this organism, formerly called "group Q streptococcus". We retrospectively evaluated the clinical features and outcomes of patients with clinically significant bacteremia caused by E. avium presenting at a tertiary-care hospital in Korea between February 1997 and February 2009. We identified 53 patients over the 12-year period; of these, 27 (50.9%) had biliary and 13 (24.5%) had intra-abdominal E. avium infections. Thirty-six (67.9%) of the episodes were polymicrobial. Thirty-three (62.3%) episodes were nosocomial bloodstream infections and resistance to vancomycin was not observed. The crude mortality rate was 24.5% (13/53), and the E. avium bacteremia-related mortality rate was 11.3% (6/53). Multivariate analysis showed that underlying rapidly fatal or ultimately fatal disease (adjusted odds ratio [AOR], 6.92; 95% confidence interval [CI], 1.56-30.65; P = 0.011) and inadequate antimicrobial therapy (AOR, 7.29; CI, 1.27-41.93; P = 0.026) were independent risk factors for mortality. In summary, bacteremia due to E. avium was commonly of biliary or intraabdominal origin and was often associated with polymicrobial bacteremia. The crude mortality rate was considerable. Severe underlying conditions and inadequate antimicrobial therapy were significant and independent risk factors for crude patient mortality.