Genotypic and phenotypic characterisation of enteroaggregative Escherichia coli from children in Rio de Janeiro, Brazil.
Enteroaggregative Escherichia coli (EAEC) is a significant cause of diarrhoeal illness in both children and adults. Genetic heterogeneity and recovery of EAEC strains from both healthy and diseased individuals complicates our understanding of EAEC pathogenesis. We wished to establish if genetic or phenotypic attributes could be used to distinguish between strains asymptomatically colonising healthy individuals and those which cause disease. Genotypic screening of a collection of twenty four EAEC isolates from children with and without diarrhoea revealed no significant differences in the repertoire of putative virulence factors present in either group of strains. In contrast, EAEC strains from phylogroup A were more strongly associated with asymptomatic groups whereas strains from phylogroup D were more associated with cases of diarrhoea. Phenotypic screening revealed no differences in the ability of strains from either cohort of children to form biofilms, to adhere to and invade cells in tissue culture or to cause disease in the Caenorhabditis elegans model of infection. However, the latter assay did reveal significant reduction in nematode killing rates when specific virulence factors were deleted from human pathogenic strains. Our results suggest that current models of infection are not useful for distinguishing avirulent from pathogenic strains of EAEC but can be useful in studying the effect of specific virulence factors.
Departamento de Microbiologia, Imunologia e Parasitologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
Fernanda L S
FL
França
Timothy J
TJ
Wells
Douglas F
DF
Browning
Raquel Tayar
RT
Nogueira
Felipe Silva
FS
Sarges
Ana Claudia
AC
Pereira
Adam F
AF
Cunningham
Kely
K
Lucheze
Ana Claudia Paula
AC
Rosa
Ian R
IR
Henderson
Maria das Graças
Md
de Luna
D000818:Animals; D001422:Bacterial Adhesion / Q000235:genetics; D018441:Biofilms; D001938:Brazil; D017173:Caenorhabditis elegans / Q000382:microbiology; D016022:Case-Control Studies; D002460:Cell Line; D002675:Child, Preschool; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000472:pathogenicity / Q000502:physiology*; D004927:Escherichia coli Infections / Q000382:microbiology*; D017353:Gene Deletion; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D010641:Phenotype; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics
D037521:Virulence Factors