Heterogeneous Virulence of EnteroaggregativeEscherichia coliStrains Isolated from Children in Southwest Nigeria

Abstract

Enteroaggregative Escherichia coli (EAEC) has been implicated in acute and persistent diarrhea, and most strains harbor a member of a partially-conserved plasmid family (called pAA). We studied EAEC isolated from Nigerian children aged <5 years to elucidate the roles of plasmid and chromosomal EAEC loci. We tested a total of 131 EAEC strains isolated from acute diarrhea case patients and control subjects for hybridization with 8 pAA plasmid-derived and 2 chromosomal gene probes, for several in vitro phenotypes and for resistance to antimicrobial agents. Using by multiple logistic regression, we found genes encoding the AAF/II fimbriae to be strongly associated with diarrhea in this population. EAEC strains appear to be of heterogeneous virulence, and data suggest that AAF/II may be a marker for pathogenic strains.

Characteristics of the enteroaggregative Shiga toxin/verotoxin-producing Escherichia coli O104:H4 strain causing the outbreak of haemolytic uraemic syndrome in Germany, May to June 2011

“…EAggEC is best known for its role in persistent diarrhoea (>14 days) in infants and children in developing countries. Studies in Mongolia [27], India [28], Brazil [29,30], Nigeria [31,32], Israel [33], Venezuela [34], Congo [35] and many other countries, have identified EAggEC as a highly prevalent (often the most prevalent) E. coli pathotype in infants. Further, the role of EAggEC as an important pathogen in AIDS patients continues to develop, and EAggEC now ranks among the most important enteric pathogens in this population group [36,37].…”

Molecular Characterization of Diarrheagenic Escherichia coli from Libya

“…[4][5][6][7][8][9] The EAEC is a heterogeneous group of organisms possessing a broad range of virulence factors. 10,11 The pathogenesis of EAEC infection is not well understood. For this reason, additional virulence genes have been used to screen EAEC-positive E. coli that include: aggR, a transcriptional activator; aggA, fimbriae AAFI; aafA, fimbriae AAF II; agg3A, fimbriae AAF III; astA, aggregative stable toxin 1 (EAST 1); pet, plasmid-encoded heat-labile toxin; aap, antiaggregation protein; and pic, protein involved in colonization.…”

Distribution and Molecular Characterization of Enteroaggregative Escherichia coli Isolated from Children in A Case-control Study of Acute Diarrhea in Thailand

“…Adherence is mediated in part by aggregative adherence fimbriae (AAF) variants I-IV [21][22][23][24][25]. As many EAEC strains lack a known fimbria, other adherence mechanisms are likely present.…”