Cluster Analysis and Genetic Characterization of Enterobacter cloacae Complex from Blood Cultures

Enterobacter cloacae bacteremia is reported as an important cause of morbidity and mortality. The members of E. cloacae complex are clinically involved in nosocomial infections. The purpose of this study was to investigate the prevalence of E. cloacae complex and its members in blood samples and conduct the hsp60 cluster analysis and genotyping of the isolates. Eight isolates of E. cloacae complex were collected from blood cultures of hospitalized patients during the study period (December 2012 to November 2013). The hsp60 sequencing was done for the genetic classification. Pulsed-field gel electrophoresis (PFGE) was used for genotyping of the isolates. Fifty percent of the isolates belonged to two E. hormaechei subspecies. Three isolates (37.5%) clustered within genotype III while only one isolate fitted cluster XIII genotype (12.5%). Pulsed-field gel electrophoresis analysis revealed four different pulsotypes. Different E. cloacae complex species and subspecies unequally contribute to the pathogenesis of blood infections and the subspecies of E. hormaechei were found to be most prevalent. Moreover, the common E. cloacae pulsotypes were observed to essentially produce identical hsp60 sequence types, indicating the probable clonality of isolates with identical pulsotypes.