Biotyping, phage typing, and O-serotyping of clinical isolates of Enterobacter cloacae.

The purpose of this study was to make an independent evaluation of the methods of bio-, phage-, and O-serotyping which had been used only in the laboratory of origin, and to assess the extent of possible cross-infection of Enterobacter cloacae in a Danish university hospital. The material consisted of 237 clinical isolates of E. cloacae from the clinical microbiology laboratory at Hvidovre Hospital. The typability of bio-, phage-, and serotyping was 100%, 83%, and 85%, respectively. Reproducibility of serotyping was 90% and of phage typing 96% if two major differences were allowed to differentiate between patterns. O-serotyping had the highest discriminatory power and combination of all typing methods further increased discrimination. Outbreaks of E. cloacae were not evident in clinical departments, but cross-infections from one department to another could not be completely ruled out. We concluded that the combination of bio-, phage- and O-serotyping is sufficiently discriminating and will be satisfactory in the majority of clinical situations.