title: Prevalence of enteroaggregative Escherichia coli and its virulence-related genes in a case-control study among children from north-eastern Brazil.
abstract: Enteroaggregative Escherichia coli (EAEC) is an important agent that causes endemic and epidemic diarrhoeal diseases worldwide. Several EAEC virulence-related genes (VRGs) have been described but their role in the clinical outcome of infection is not completely defined. This study investigated the prevalence of EAEC and potential associations of its VRGs with risk of or protection from diarrhoeal diseases in children from urban communities in north-eastern Brazil. The case-control study included 166 children, who had their stools evaluated for the EAEC diagnostic genes (aaiC and aatA) using PCR. Positive samples were further analysed by multiplex PCR and identified 18 VRGs. EAEC was found in the same proportion in both groups (41%). The plasmid-borne gene encoding a hexosyltransferase homologue (capU) was the most frequently detected (89.6%), followed by dispersin protein (aap, 58.2%) and EAEC HilA homologue (eilA, 57.8%). The AAF/III fimbrial subunit (agg3A) gene was observed at lower frequency (1.5%). Plasmid-encoded toxin (pet) or AAF/II fimbrial subunit (aafA) was associated significantly with disease. AAF/IV fimbrial subunit (agg4A) or hypothetical plasmid-encoded haemolysin (orf61) was detected significantly more in controls than in children with diarrhoea. In addition, one set of genes in combination, aaiC and agg3/4C but lacking agg4A and orf61, was associated with diarrhoea cases; and another one, orf61 in the absence of pet and aafA, was correlated with control children. These data confirm a high prevalence, endemicity and heterogeneity of EAEC strains in the developing urban areas of north-eastern Brazil. Statistical correlation between cases and controls was seen with either isolated or combined sets of genes, suggesting that the pathophysiology of EAEC infection involves a complex and dynamic modulation of several VRGs.
authors: Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Ila Fernanda Nunes
authors: IFN
authors: Lima
authors: Center for Global Health, Division of Infectious Diseases and International Health, Departments of Medicine and Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA, USA.
authors: Nadia
authors: N
authors: Boisen
authors: Josiane da Quetz
authors: JDQ
authors: Silva
authors: Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Alexandre
authors: A
authors: Havt
authors: Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Eunice Bobo
authors: EB
authors: de Carvalho
authors: Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Alberto Melo
authors: AM
authors: Soares
authors: Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Noélia Leal
authors: NL
authors: Lima
authors: Departament of Statistics and Applied Mathematics, Science Center, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Rosa Maria Salani
authors: RMS
authors: Mota
authors: Center for Global Health, Division of Infectious Diseases and International Health, Departments of Medicine and Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA, USA.
authors: James P
authors: JP
authors: Nataro
authors: Center for Global Health, Division of Infectious Diseases and International Health, Departments of Medicine and Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA, USA.|Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Richard Littleton
authors: RL
authors: Guerrant
authors: Center for Global Health, Division of Infectious Diseases and International Health, Departments of Medicine and Pediatrics, School of Medicine, University of Virginia, Charlottesville, VA, USA.|Institute of Biomedicine for Brazilian Semi-Arid and Clinical Research Unit/Center for Global Health, School of Medicine, Federal University of Ceara, Fortaleza, CE, Brazil.
authors: Aldo Ângelo Moreira
authors: AÂM
authors: Lima
mesh_terms: D001938:Brazil / Q000453:epidemiology; D016022:Case-Control Studies; D002675:Child, Preschool; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology*; D005260:Female; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D014774:Virulence