Prevalences of the Enterobacter cloacae complex and its phylogenetic derivatives in the nosocomial environment

Despite the importance of the Enterobacter cloacae complex as a nosocomial pathogen, little is known about the relative contribution of its single species and genotypes to its pathogenicity. We studied here the relationship between phylogenetically related strains and clinical infection sites. A total of 196 prospectively collected isolates of the E. cloacae complex were included in the study, comprising 67 blood culture isolates. Isolates were analyzed for clonality by pulsed-field gel electrophoresis (PFGE) and genetically assigned to their genotypes by partial hsp60 sequencing. Most isolates belonged in phylogenetic clade 1, with E. hormaechei being the most prevalent species. Notably, some genotypes and species, indeed, showed predilections to certain clinical specimens, whereas clinical outbreaks with members of the E. cloacae complex were rare. Our study stresses the need to identify alleged E. cloacae isolates on the subspecies level in clinical routine in order to obtain more insight into their distinct infectious potentials.