title: Outbreak of extended-spectrum β-lactamase-producing Escherichia coli transmitted through breast milk sharing in a neonatal intensive care unit.
abstract: BACKGROUND
  Routine surveillance in a neonatal intensive care unit (NICU) showed an increased detection of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-E. coli) in August 2012, following nearly a year without detection.
  
  
  OBJECTIVE
  To describe the investigation and interventions by a hospital infection control team of an outbreak of ESBL-E. coli in a NICU.
  
  
  METHODS
  Six neonates with positive cultures of ESBL-E. coli (five with respiratory colonization, one with a urinary tract infection), control infants who were negative for ESBL-E. coli during the study period, and mothers who donated their breast milk were included. A case-control study was performed to identify possible risk factors for positive ESBL-E. coli cultures and molecular typing of isolated strains by pulsed-field gel electrophoresis.
  
  
  RESULTS
  The odds ratio for ESBL-E. coli infection after receiving shared unpasteurized breast milk during the study period was 49.17 (95% confidence interval: 6.02-354.68; P < 0.05). The pulsed-field gel electrophoresis pattern showed that all strains were identical, and the same pathogen was detected in freshly expressed milk of a particular donor. After ceasing the breast milk sharing, the outbreak was successfully terminated.
  
  
  CONCLUSIONS
  This outbreak indicates that contamination of milk packs can result in transmission of a drug-resistant pathogen to newborn infants. Providers of human breast milk need to be aware of the necessity for low-temperature pasteurization and bacterial cultures, which should be conducted before and after freezing, before prescribing to infants.
authors.affiliation: Department of Infection Control, Fukushima Medical University, Fukushima, Japan; Infection Control Unit, Fukushima Medical University Hospital, Fukushima, Japan. Electronic address: kinakamu@fmu.ac.jp.
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Department of Pediatrics, Fukushima Medical University, Fukushima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kaneko
authors.affiliation: Department of Emergency and Critical Care Medicine, Fukushima Medical University, Fukushima, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Abe
authors.affiliation: Department of Infection Control, Fukushima Medical University, Fukushima, Japan; Infection Control Unit, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Infection Control Unit, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Mori
authors.affiliation: Infection Control Unit, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Yoshida
authors.affiliation: Department of Clinical Laboratory Medicine, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohashi
authors.affiliation: Department of Infection Control, Fukushima Medical University, Fukushima, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Miura
authors.affiliation: Department of Infection Control, Fukushima Medical University, Fukushima, Japan.
authors.forename: T T
authors.initials: TT
authors.lastname: Yang
authors.affiliation: Department of Pediatrics, Fukushima Medical University, Fukushima, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Momoi
authors.affiliation: Department of Infection Control, Fukushima Medical University, Fukushima, Japan; Infection Control Unit, Fukushima Medical University Hospital, Fukushima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kanemitsu
mesh_terms: D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission; D004196:Disease Outbreaks; D018562:Disease Transmission, Infectious; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*; D005260:Female; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D008297:Male; D008895:Milk, Human / Q000382:microbiology*; D058889:Molecular Typing; D012307:Risk Factors; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases
keywords: Breast milk sharing; Extended-spectrum β-lactamase-producing E. coli; Neonatal intensive care unit