title: Genotypic and phenotypic characterization of invasive neonatal Escherichia coli clinical isolates.
abstract: OBJECTIVE
  The objective of this study was to describe the clinical characteristics of neonates with Escherichia coli bacteremia and the antibiotic resistance pattern of the bacterial isolates. We assessed the isolates' genetic relatedness and virulence phenotypic characteristics in vitro.
  
  
  METHODS
  A total of 24 neonates with E. coli bacteremia were identified prospectively in a tertiary-care hospital. Clinical and antibiotic resistance data were investigated. The E. coli isolates were analyzed by multilocus sequence typing (MLST); the presence of the K1 capsule and their ability to invade intestinal epithelial cells were also assessed.
  
  
  RESULTS
  Most newborns were very low birth weight infants. Overall, 75% of the isolates were ampicillin resistant and 17% were gentamicin and tobramycin nonsusceptible. MLST determined sequence types 95 and 131 (ST95 and ST131) predominated, with ST131 becoming significantly more prevalent recently. The K1 capsule was present in 50% of the isolates. ST131 isolates and those producing bacteremia in newborns younger than 7 days showed a highly invasive phenotype.
  
  
  CONCLUSIONS
  Resistance to antibiotics currently used empirically to treat newborns is present in bacteremia-producing E. coli. Clonal spread among newborns of multidrug-resistant E. coli is possible; therefore, continued surveillance is needed. Identification of additional virulence factors associated with increased invasion in neonatal E. coli strains is important and further studies are warranted.
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
authors.forename: Salika Mehreen
authors.initials: SM
authors.lastname: Shakir
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
authors.forename: Jessica Marie
authors.initials: JM
authors.lastname: Goldbeck
authors.affiliation: Clinical Microbiology Laboratory, OU Medical Center, Oklahoma City, Oklahoma.
authors.forename: Denise
authors.initials: D
authors.lastname: Robison
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
authors.forename: Annette Marie
authors.initials: AM
authors.lastname: Eckerd
authors.affiliation: Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma.
authors.forename: Susana
authors.initials: S
authors.lastname: Chavez-Bueno
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D000942:Antigens, Bacterial / Q000032:analysis; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology*; D016667:Bacterial Capsules / Q000276:immunology; D015373:Bacterial Typing Techniques; D002478:Cells, Cultured; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000276:immunology; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D005838:Genotype; D005839:Gentamicins / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D058885:Multilocus Sequence Typing; D010641:Phenotype; D014031:Tobramycin / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D000942:Antigens, Bacterial; D005839:Gentamicins; D014031:Tobramycin