title: ESBL-producing Enterobacteriaceae in 24 neonatal units and associated networks in the south of England: no clustering of ESBL-producing Escherichia coli in units or networks.
abstract: OBJECTIVE
  The objectives of this study were to characterize ESBL-producing Enterobacteriaceae present in 24 neonatal units (NNUs) in eight networks participating in a multicentre probiotic study and to test the hypothesis that specific strains would cluster within individual units and networks.
  
  
  METHODS
  We performed analysis of stool samples for the presence of ESBL-producing Enterobacteriaceae at 2 weeks post-natal age and 36 weeks post-menstrual age. ESBL-producing Enterobacteriaceae were characterized and typed using molecular methods.
  
  
  RESULTS
  ESBL-producing Enterobacteriaceae (n = 71) were isolated from 67/1229 (5.5%) infants from whom we received a sample at either sampling time or both sampling times, and from infants in 18 (75%) of the 24 recruiting NNUs. Thirty-three Escherichia coli, 23 Klebsiella spp. and 6 Enterobacter spp. strains were characterized. ESBL-producing E. coli were all distinguishable within individual NNUs by antibiotic resistance genotype, serogroup (O25b), phenotype, phylotype or ST. Ten of the 33 were ST131 and 9 of the 10 ST131 isolates were ciprofloxacin resistant. Seven of the 10 ST131 isolates carried genes encoding CTX-M group 1 enzymes. ST131 isolates were isolated from centres within five of the eight NNU networks. There were clusters of indistinguishable ESBL-producing Klebsiella and Enterobacter isolates associated with specific NNUs.
  
  
  CONCLUSIONS
  Strains of E. coli ST131 were distributed across neonatal networks in the south of England. There was no evidence of clustering of clonally related ESBL-producing E. coli strains, by contrast with Klebsiella spp. and Enterobacter spp., which did cluster within units. The possibility that ESBL-producing E. coli strains are spread by vertical transmission requires further investigation.
authors.affiliation: Department of Infection, Barts Health NHS Trust, 3rd Floor, Pathology and Pharmacy Building, 80 Newark Street, Whitechapel, London E1 2ES, UK michael.millar@bartshealth.nhs.uk.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Millar
authors.affiliation: Department of Infection, Barts Health NHS Trust, 3rd Floor, Pathology and Pharmacy Building, 80 Newark Street, Whitechapel, London E1 2ES, UK.
authors.forename: Jo
authors.initials: J
authors.lastname: Seale
authors.affiliation: Public Health England, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Turton
authors.affiliation: Department of Infection, Barts Health NHS Trust, 3rd Floor, Pathology and Pharmacy Building, 80 Newark Street, Whitechapel, London E1 2ES, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Wilks
authors.affiliation: Blizard Institute, Queen Mary, University of London, London, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: Costeloe
authors.affiliation: Public Health England, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Woodford
authors.affiliation: National Perinatal Epidemiology Unit, Oxford, UK.
authors.forename: Ed
authors.initials: E
authors.lastname: Juszczak
authors.affiliation: Department of Infection, Barts Health NHS Trust, 3rd Floor, Pathology and Pharmacy Building, 80 Newark Street, Whitechapel, London E1 2ES, UK.
authors.forename: Angela
authors.initials: A
authors.lastname: Whiley
authors.affiliation: Department of Infection, Barts Health NHS Trust, 3rd Floor, Pathology and Pharmacy Building, 80 Newark Street, Whitechapel, London E1 2ES, UK.
authors.forename: Nicola
authors.initials: N
authors.lastname: Panton
authors.affiliation: Blizard Institute, Queen Mary, University of London, London, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Wareham
mesh_terms: D016000:Cluster Analysis; D004739:England / Q000453:epidemiology; D004755:Enterobacteriaceae / Q000145:classification* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000453:epidemiology* / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017720:Molecular Epidemiology; D058889:Molecular Typing; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001618:beta-Lactamases