Study of an outbreak of Enterobacter cloacae sepsis in a neonatal intensive care unit: the application of epidemiologic chromosome profiling by pulsed-field gel electrophoresis.
OBJECTIVE
From October 1996 to March 1997, a cluster of 11 cases of neonatal sepsis caused by Enterobacter cloacae with similar antimicrobial susceptibility patterns occurred in a neonatal intensive care unit. This outbreak prompted an investigation.


METHODS
Twelve isolates obtained from 6 neonatal patients who developed E cloacae sepsis during the outbreak were analyzed. Four E cloacae isolates from 2 preterm neonates without E cloacae infection on the same ward, and 1 isolate from the hands of a nurse, were also examined. No E cloacae were isolated from the environment. Bacterial DNA digested with XbaI or NotI was analyzed with pulsed-field gel electrophoresis.


RESULTS
Three distinct banding patterns were identified by pulsed-field gel electrophoresis. Of the 6 preterm infants with sepsis, strain I was identified in 1, strain II in 2, a mixed infection of strains I and II in 2, and strain III was found in only 1 infant. An isolate from the hands of a nurse was identified as strain II, as were the 4 isolates from the 2 preterm neonates without E cloacae infection. Thus, this outbreak of sepsis was caused by 2 genotypes of E cloacae.


CONCLUSIONS
This study demonstrates that pulsed-field gel electrophoresis with restriction enzyme digestion is a valuable tool for genetic characterization of multidrug-resistant E cloacae strains during outbreaks.
Liu
Shu-Chih
SC
Division of Infectious Diseases, Department of Pediatrics, Chung Shan Medical and Dental College Hospital, Taichung, Taiwan.
Leu
Hsieh-Shong
HS
Yen
Muh-Yong
MY
Lee
Ping-Ing
PI
Chou
Ming-Chih
MC
D015373:Bacterial Typing Techniques; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D016972:Enterobacter cloacae / Q000235:genetics* / Q000302:isolation & purification*; D004756:Enterobacteriaceae Infections / Q000453:epidemiology / Q000382:microbiology; D005260:Female; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D012307:Risk Factors; D018805:Sepsis / Q000453:epidemiology* / Q000382:microbiology*