title: Characterizing the pathotype of neonatal meningitis causing Escherichia coli (NMEC).
abstract: BACKGROUND
  Neonatal meningitis-causing Escherichia coli (NMEC) is the predominant Gram-negative bacterial pathogen associated with meningitis in newborn infants. High levels of heterogeneity and diversity have been observed in the repertoire of virulence traits and other characteristics among strains of NMEC making it difficult to define the NMEC pathotype. The objective of the present study was to identify genotypic and phenotypic characteristics of NMEC that can be used to distinguish them from commensal E. coli.
  
  
  METHODS
  A total of 53 isolates of NMEC obtained from neonates with meningitis and 48 isolates of fecal E. coli obtained from healthy individuals (HFEC) were comparatively evaluated using five phenotypic (serotyping, serum bactericidal assay, biofilm assay, antimicorbial susceptibility testing, and in vitro cell invasion assay) and three genotypic (phylogrouping, virulence genotyping, and pulsed-field gel electrophoresis) methods.
  
  
  RESULTS
  A majority (67.92%) of NMEC belonged to B2 phylogenetic group whereas 59% of HFEC belonged to groups A and D. Serotyping revealed that the most common O and H types present in NMEC tested were O1 (15%), O8 (11.3%), O18 (13.2%), and H7 (25.3%). In contrast, none of the HFEC tested belonged to O1 or O18 serogroups. The most common serogroup identified in HFEC was O8 (6.25%). The virulence genotyping reflected that more than 70% of NMEC carried kpsII, K1, neuC, iucC, sitA, and vat genes with only less than 27% of HFEC possessing these genes. All NMEC and 79% of HFEC tested were able to invade human cerebral microvascular endothelial cells. No statistically significant difference was observed in the serum resistance phenotype between NMEC and HFEC. The NMEC strains demonstrated a greater ability to form biofilms in Luria Bertani broth medium than did HFEC (79.2% vs 39.9%).
  
  
  CONCLUSIONS
  The results of our study demonstrated that virulence genotyping and phylogrouping may assist in defining the potential NMEC pathotype.
authors.affiliation: Department of Veterinary and Biomedical Sciences, Pennsylvania State University, 115 Henning Bldg, University Park, Pennsylvania, USA. dsw179@psu.edu.
authors.forename: D S S
authors.initials: DS
authors.lastname: Wijetunge
authors.affiliation: Department of Veterinary and Biomedical Sciences, Pennsylvania State University, 115 Henning Bldg, University Park, Pennsylvania, USA. srg220@psu.edu.
authors.forename: S
authors.initials: S
authors.lastname: Gongati
authors.affiliation: E. coli Reference Center, Department of Veterinary and Biomedical Sciences, Pennsylvania State University, University Park, Pennsylvania, USA. rcd3@psu.edu.
authors.forename: C
authors.initials: C
authors.lastname: DebRoy
authors.affiliation: Division of Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. kwangkim@jhmi.edu.
authors.forename: K S
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Department of Cell Biology, University of Paris Descartes, Paris, France. pierre-olivier.couraud@inserm.fr.
authors.forename: P O
authors.initials: PO
authors.lastname: Couraud
authors.affiliation: Department of Biological Sciences, Open University, Milton Keynes, UK. i.romero@open.ac.uk.
authors.forename: I A
authors.initials: IA
authors.lastname: Romero
authors.affiliation: Department of Medicine, Weill Cornell Medical College in New York, New York, USA. babette@med.cornell.edu.
authors.forename: B
authors.initials: B
authors.lastname: Weksler
authors.affiliation: Department of Veterinary and Biomedical Sciences, Pennsylvania State University, 115 Henning Bldg, University Park, Pennsylvania, USA. sxk91@psu.edu.|Center for Molecular Immunology and Infectious Disease, Pennsylvania State University, University Park, Pennsylvania, USA. sxk91@psu.edu.
authors.forename: S
authors.initials: S
authors.lastname: Kariyawasam
mesh_terms: D018441:Biofilms / Q000254:growth & development; D001770:Blood Bactericidal Activity; D004705:Endocytosis; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D004927:Escherichia coli Infections / Q000382:microbiology*; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D016920:Meningitis, Bacterial / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010641:Phenotype; D065288:Serogroup; D037521:Virulence Factors / Q000235:genetics
chemical_list: D037521:Virulence Factors