Emergence of Enterobacter cloacae as a common pathogen in neonatal units: pulsed-field gel electrophoresis analysis D. Talon a, *, P. Menget b , M. Thouverez a , G. Thiriez b , H. Gbaguidi Haore a , C. Fromentin b , A. Muller a , X. Bertrand a a Service d’Hygie `ne Hospitalie `re et d’Epide ´miologie mole ´culaire, 25030 Besanc ¸on cedex, France b Service de ne ´onatologie, Centre Hospitalier Universitaire Jean Minjoz, 25030 Besanc ¸on cedex, France Received 12 August 2003; accepted 21 January 2004 Available online 13 May 2004 KEYWORDS Enterobacter cloacae; Molecular epidemiology; Neonatal units; Antibiotic use Summary In the first week of December 2002, three infants hospitalized in the neonatal department of our hospital had blood cultures positive with Enterobacter cloacae. Screening cultures and genotyping showed that 10 of 25 screened patients also carried E. cloacae and that nine isolates belonged to the same clone as that responsible for all three bacteraemias. This epidemic cluster was limited to one of the two units of the department. Surveillance of both units continued until the end of March 2003; 51 of 159 neonates screened were colonized with E. cloacae, 38 out of 80 (47.5%) in the premature unit (PU) and 13 out of 79 (16.4%) in the paediatric intensive care unit (PICU). Pulsed-field gel electrophoresis (PFGE) analysis of 130 available isolates revealed 30 different pulsotypes, including 24 unique pulsotypes from individual patients and six from multiple patients. Antibiotic (particularly b-lactam) use did not significantly vary from 1999 to 2003. The consumption of alcohol-based hand rub (four-fold higher in the PICU than in the PU) and nurse-to-patient ratio (1:2 in the PICU and 1:4 in the PU) might explain the higher cross-transmission rate in the PU. Finally, despite an epidemiological survey, we failed to identify the causes of the emergence of E. cloacae in our neonatology units. However, improved hygiene practices combined with restriction of admission led to the progressive disappearance of the epidemic strain. The increasing importance of this type of unit and the dramatic consequences of infections emphasize the need for additional research on the constitution of the flora of newborns and the mode of acquisition Gram- negative multi-resistant bacteria. Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. 0195-6701/$ - see front matter Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jhin.2004.01.023 Journal of Hospital Infection (2004) 57, 119–125 www.elsevierhealth.com/journals/jhin * Corresponding author. Tel.: þ33-381-668286; fax: þ33-381-668914. E-mail address: daniel.talon@ufc-chu.univ-fcomte.fr