Analysis of plasmid pattern in paediatric intensive care unit outbreaks of nosocomial infection due to Enterobacter cloacae.

Sequential outbreaks of nosocomial infection due to multiply-resistant Enterobacter cloacae occurred in September 1987, and between December 1988 and January 1989, in a paediatric intensive care unit. A total of eight neonates were affected and most had received ventilatory support. Initially, we were unable to determine whether the two outbreaks were caused by the same strain of E. cloacae. After applying plasmid profile analysis to identify epidemic strains, we established that the strain from the first outbreak was different from the second outbreak strain, as each had its own plasmid pattern. During the second outbreak, an environmental bacteriological survey was carried out. We found that the distilled water containers were contaminated with E. cloacae which had the same plasmid profile. After changing the distilled water containers and by reinforcement of aseptic techniques, the nosocomial outbreak was terminated.