Bacteremia caused by non-faecalis and non-faecium enterococcus species at a Medical center in Taiwan, 2000 to 2008

SummaryObjectivesHuman infections due to non-faecalis and non-faecium Enterococcus species are emerging but data on the characteristics of these infections are limited.MethodsWe retrospectively reviewed the computerized database of the bacteriology laboratory at National Taiwan University Hospital from January 2000 through December 2008 to identify patients with non-faecalis and non-faecium enterococcal bacteremia.ResultsEnterococcal bacteremia was diagnosed in 1887 patients during the study period and was caused by non-faecalis and non-faecium enterococci in 182 (9.6%) of these patients. The causative organisms included Enterococcus casseliflavus (n = 59, 3.1%), Enterococcus gallinarum (n = 58, 3.0%), Enterococcus avium (n = 45, 2.4%), Enterococcus hirae (n = 9, 0.5%), Enterococcus raffinosus (n = 9, 0.5%), Enterococcus durans (n = 2, 0.1%), Enterococcus cecorum (n = 2, 0.1%), and Enterococcus canintestini (n = 1, 0.5%). A commercially-available phenotypic identification system misidentified six isolates based upon sequence analysis of 16S and groESL genes. Among the 182 patients, 74 (40.7%) had catheter-associated bloodstream infection and 69 (37.9%) presented with biliary tract infection. Healthcare-associated enterococcal bacteremia comprised 99 (54.4%) episodes and a polymicrobial etiology was found in 106 (58.2%) episodes. The clinical manifestations varied between the infecting Enterococcus species. Multivariate logistic regression showed that immunocompromised status is the only risk factor for the all cause mortality.ConclusionsNon-faecalis and non-faecium Enterococcus species can cause protean manifestations which vary with the infecting Enterococcus species. Misidentification of unusual enterococcal species might occur by the commercial identification methods and accurate identification with molecular methods is required.