[Epidemiology of enterobacteriaceae causing bloodstream infections in neonatal intensive care unit patients]

An increasing number of neonates require intensive care, and this population has a high risk of developing infections. The Enterobacteriaceae most commonly related to healthcare-associated infection in neonatal intensive care units (NICU) are Escherichia coli, Klebsiella spp and Enterobacter cloacae.

From January 2001 to December 2005, 84 bloodstream infections caused by E. cloacae, E. coli and Klebsiella spp. were studied in 80 neonates hospitalized in the NICU and intermediate care unit. Clinical histories were reviewed to extract the most important demographic data. Identification and susceptibility patterns were carried out with GN VITEK 2 and AST_N057 VITEK 2 (bioMérieux, Marcy l'Etoile, France). Molecular typing was performed by macrorestriction and pulsed-field gel electrophoresis (PFGE).

Twenty-one community bloodstream infections and 63 healthcare-associated infections were diagnosed. In community bloodstream infections there were no significant differences according to birth weight or gestational age of the neonates. In healthcare-associated infection, however, there was a high percentage of neonates whose birth weight was between 1.001 and 1.500 grams and gestational age < or =36 weeks (P<0.001). On PFGE analysis, the majority of E. coli strains belonged to different clones. Among Klebsiella pneumoniae and E. cloacae isolates, some strains showed a high percentage of similarity, highlighting detection of an E. cloacae outbreak.

The study has provided better knowledge of bloodstream infections caused by Enterobacteriaceae in the NICU of our hospital from both the epidemiological and clonal standpoints.