INTERREPEAT FINGERPRINTING OF 3RD-GENERATION CEPHALOSPORIN-RESISTANT ENTEROBACTER-CLOACAE ISOLATED DURING AN OUTBREAK IN A NEONATAL INTENSIVE-CARE-UNIT

OBJECTIVE: To investigate an outbreak in neonates of Enterobacter cloa cae infection resistant to third-generation cephalosporins. DESIGN: A retrospective study of an outbreak in the neonatal intensive care unit (NICU) and review of E cloacae isolates in pediatric wards and other intensive care units from June 1992 through March 1993. SETTING: An ac ademic tertiary care hospital. PATIENTS: Six patients admitted to the NICU were colonized or infected with E cloacae resistant to third-gene ration cephalosporins. In the period preceding the outbreak, four E cl oacae isolates were available from four patients in the pediatric surg ical ward. Nine isolates from four patients in two other intensive car e units (ICUs) also were collected during the outbreak. Isolates were biotyped by the API 50CH system and genotyped by polymerase chain reac tion (PCR) fingerprinting. RESULTS: Typing by interrepeat PCR showed t hat 21 isolates, which were obtained from five neonates, were identica l. One neonate was colonized with a different strain. Some neonates we re colonized with a single type of E cloacae for a relatively long per iod of time. Isolates of patients who were cared for in the pediatric surgical ward and the two other intensive care units (ICUs) showed dif ferent genotypes. One patient in an ICU was colonized with an E cloaca e strain genetically identical to the outbreak strain. No predominant biotype could be established. CONCLUSIONS: E cloacae can colonize neon ates for a long period of time and although colonization with E cloaca e initially may arise endogenously, we were able to show further trans mission by cross-contamination in a neonatal intensive care unit