Genomic Characterization of Enteroaggregative Escherichia Coli From Children in Mali

J Infect Dis. 2012 Feb 1;205(3):431-44. doi: 10.1093/infdis/jir757. Epub 2011 Dec 19.

Abstract

Background: Enteroaggregative Escherichia coli (EAEC) is a cause of epidemic and sporadic diarrhea, yet its role as an enteric pathogen is not fully understood.

Methods: We characterized 121 EAEC strains isolated in 2008 as part of a case-control study of moderate to severe acute diarrhea among children 0-59 months of age in Bamako, Mali. We applied multiplex polymerase chain reaction and comparative genome hybridization to identify potential virulence factors among the EAEC strains, coupled with classification and regression tree modeling to reveal combinations of factors most strongly associated with illness.

Results: The gene encoding the autotransporter protease SepA, originally described in Shigella species, was most strongly associated with diarrhea among the EAEC strains tested (odds ratio, 5.6 [95% confidence interval, 1.92-16.17]; P = .0006). In addition, we identified 3 gene combinations correlated with diarrhea: (1) a clonal group positive for sepA and a putative hemolysin; (2) a group harboring the EAST-1 enterotoxin and the flagellar type H33 but no other previously identified EAEC virulence factor; and (3) a group carrying several of the typical EAEC virulence genes.

Conclusion: Our data suggest that only a subset of EAEC strains are pathogenic in Mali and suggest that sepA may serve as a valuable marker for the most virulent isolates.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Case-Control Studies
  • Child, Preschool
  • Comparative Genomic Hybridization
  • DNA, Bacterial / genetics
  • Diarrhea / epidemiology
  • Diarrhea / microbiology
  • Escherichia coli / classification*
  • Escherichia coli / genetics*
  • Escherichia coli / isolation & purification
  • Escherichia coli Infections / epidemiology*
  • Escherichia coli Infections / microbiology*
  • Escherichia coli Proteins / genetics
  • Genome, Bacterial
  • Genotype
  • Hemolysin Proteins / genetics
  • Humans
  • Infant
  • Infant, Newborn
  • Mali / epidemiology
  • Molecular Epidemiology
  • Multiplex Polymerase Chain Reaction
  • Peptide Hydrolases / genetics
  • Virulence Factors / genetics*

Substances

  • Bacterial Proteins
  • DNA, Bacterial
  • Escherichia coli Proteins
  • Hemolysin Proteins
  • SepA protein, Shigella
  • Virulence Factors
  • Peptide Hydrolases
  • SepA protein, E coli