ABSTRACT
OBJECTIVE: To investigate the molecular epidemiology of systemic nosocomial infections caused by Enterobacter cloacae. SETTING: Neonatal intensive care unit (NICU) of a tertiary-care university hospital. PATIENTS: Forty-two high-risk neonates with systemic infections caused by E. cloacae. METHODS: From 1995 to 1997, the variables associated with death in these patients were evaluated. The molecular epidemiology of the strains responsible for the systemic infections, and 14 unrelated strains, was studied using plasmid analysis and pulsed-field gel electrophoresis (PFGE). RESULTS: The overall mortality rate for infection caused by E. cloacae was 34%, whereas the crude mortality rate during the study period was 8.12% (P < .001). Gestational age (preterm neonates) and birth weight (small for gestational age) were not associated with a higher risk of death. Insertion of a venous catheter by dissection of a peripheral vein was the only invasive procedure related to death (P = .016) in this study. A molecular analysis showed that three outbreaks, each occurring in a different year, were caused by strains with distinctive DNA profiles. Only one outbreak was identified by the infection control service, in the NICU. Plasmid analysis and PFGE showed similar ability to discriminate control strains from the E. cloacae strains isolated from the neonates. CONCLUSIONS: Systemic infections caused by E. cloacae in our NICU were associated with a high mortality rate and occurred as small, unrecognized outbreaks. These results may not be generalizable because the data were from a single center.
