title: Emergence of Antibiotic Resistance-Associated Clones Among Escherichia coli Recovered From Newborns With Early-Onset Sepsis and Meningitis in the United States, 2008-2009.
abstract: BACKGROUND
  Escherichia coli associated with early-onset sepsis (EOS) have historically been antibiotic-susceptible and K1-encapsulated. In the era of emerging antibiotic resistance, however, the clonal makeup of E coli associated with EOS has not been well characterized.
  
  
  METHODS
  Escherichia coli isolates were collected from 28 cases of EOS and early-onset meningitis (EOM) from April 2008 through December 2009, during a parent study conducted at National Institute of Child Health and Human Development Neonatal Research Network centers from February 2006 through December 2009. Clinical and microbiologic data were collected for the parent study. We applied polymerase chain reaction- and sequence-based molecular techniques to determine clonal, virulence-associated and antibiotic resistance-associated traits of the E coli isolates.
  
  
  RESULTS
  Among 28 E coli strains, phylogroup B2 strains predominated (68%), of which more than half were K1-encapsulated (53%). Phylogroup D strains were prominent as well (18%), but none were K1-encapsulated. Across the strain collection, the rate of ampicillin resistance was high (78%). The sole strain resistant to either extended-spectrum cephalosporins or fluoroquinolones represented ST131 H30-Rx, the multidrug-resistant subclone that has emerged worldwide in the last decade. This strain encoded extended-spectrum β-lactamase CTX-M-15 and carried an IncF plasmid of type F2:A1:B-.
  
  
  CONCLUSIONS
  In this collection of EOS/EOM-associated E coli isolates, we observed a high rate of ampicillin resistance, a low rate of fluoroquinolone resistance, and no aminoglycoside resistance, with resistance to third-generation cephalosporins appearing in only a single strain, from the worldwide emerging ST131 clone. Ongoing surveillance of antibiotic resistance among EOS isolates is warranted, to ensure that standard empiric regimens remain effective.
authors.affiliation: Center for Global Infectious Disease Research, Seattle Children's Research Institute, Washington.
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Weissman
authors.affiliation: Social, Statistical and Environmental Sciences, RTI International, Research Triangle Park, North Carolina.
authors.forename: Nellie I
authors.initials: NI
authors.lastname: Hansen
authors.affiliation: Social, Statistical and Environmental Sciences, RTI International, Research Triangle Park, North Carolina.
authors.forename: Kristen
authors.initials: K
authors.lastname: Zaterka-Baxter
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
authors.forename: Rosemary D
authors.initials: RD
authors.lastname: Higgins
authors.affiliation: Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia Children's Healthcare of Atlanta, Georgia Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network, Bethesda, Maryland.
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: Stoll
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology; D000668:Ampicillin Resistance; D015373:Bacterial Typing Techniques; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D007231:Infant, Newborn; D016920:Meningitis, Bacterial / Q000453:epidemiology / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D000071074:Neonatal Sepsis / Q000453:epidemiology / Q000382:microbiology*; D010802:Phylogeny; D010957:Plasmids; D014481:United States / Q000453:epidemiology; D014774:Virulence
chemical_list: D000617:Aminoglycosides; D024841:Fluoroquinolones
keywords: Escherichia coli; ST131; antibiotic resistance; early-onset sepsis