title: Evidence for the presence of a type III secretion system in diffusely adhering Escherichia coli (DAEC).
abstract: Diffusely adhering Escherichia coli (E. coli) strains (DAEC) represent a potential cause of diarrhoea in infants, and the detection of type three secretion system (TTSS) genes in DAEC would substantiate their pathogenic nature. In this work, four isolates of DAEC, recovered from stools of diarrhoeic children, were analysed by PCR, in order to detect the presence of TTSS genes. Primers targeted to the escC, escJ, escN and escV, some of the most conserved TTSS genes in enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), were used in order to verify the occurrence of homologous genes in our DAEC isolates. By this approach, we were able to characterise DNA fragments corresponding to putative escJ and escN genes in all DAEC isolates. Furthermore, DNA fragments homologous to the escC and escV genes were also amplified from all isolates. Besides the similarity found among the DAEC esc homologues with EPEC and EHEC esc genes, the nucleotide sequence analysis of the flanking regions of the amplified DNA fragments suggests that the putative DAEC esc genes are organised in the same manner as observed in EPEC and in EHEC strains. The results described here provide strong evidence for the presence of a TTSS in the DAEC strains analysed, implicating a pathogenic nature of these isolates.
authors.affiliation: Departamento de Biologia Celular, Instituto de Biologia, Laboratório de Microbiologia, Universidade de Brasília, Campus Universitário Darcy Ribeiro, Asa Norte, Distrito Federal, CEP 70910-900 Brasília, Brazil.
authors.forename: C M
authors.initials: CM
authors.lastname: Kyaw
authors.forename: C R
authors.initials: CR
authors.lastname: De Araujo
authors.forename: M R
authors.initials: MR
authors.lastname: Lima
authors.forename: E G S
authors.initials: EG
authors.lastname: Gondim
authors.forename: M M
authors.initials: MM
authors.lastname: Brígido
authors.forename: L G
authors.initials: LG
authors.lastname: Giugliano
mesh_terms: D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002648:Child; D017124:Conserved Sequence; D004269:DNA, Bacterial; D003967:Diarrhea / Q000382:microbiology; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology; D005798:Genes, Bacterial; D006801:Humans; D010802:Phylogeny; D012689:Sequence Homology, Nucleic Acid; D012703:Serotyping
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial