title: Incidence of virulence-encoding genes among enteric Escherichia coli strains isolated from healthy subjects.
abstract: Escherichia coli, heterogeneous species consisting of commensal and pathogenic strains, is causing a broad spectrum of intestinal and extra intestinal diseases, ranging from asymptomatic infections to septicaemia, according to its capacity to produce different virulence factors. The incidence of different virulence-associated genes among the strains isolated from healthy subjects, taking into account that the human gastrointestinal tract is considered an important source for spreading E. coli strains, was evaluated. A total of 241 E. coli strains isolated from 41 healthy subjects, working in the food chain and coming to the laboratory for periodical medical control, were investigated for harbouring patogenicity factors--encoding genes. Extra intestinal virulence-associated genes, pap, sfa/foc, afa, hly, cnf and intestinal ones eaea, bfp, agg, It, st, vtx1 (stx1), vtx2 (stx2) and ipaH, were targeted by PCR using cellular lysate for total DNA. Genes encoding for adherence were the most prevalent. A number of 67 strains (27.80%) were positive for pap genes and 34 strains (14.11%) presented PCR positive results when afa genes were targeted, but sfa/foc genes were identified in only 10 strains (4.15%). Genes encoding for toxigenesis were less prevalent. A total of 9 strains amplified hly genes, 2.49% were positive for cnf genes and only 2 strains presented vtx1(stx1) gene. The results are in concordance with those which demonstrate that healthy subjects carrying strains possessing virulence-encoding genes could represent a reservoir for environmental circulation of such strains, considered life-threatening when a receptive host is encountered.
authors.affiliation: "Cantacuzino" National Institute of Research-Development for Microbiology and Immunology, Bucharest, Romania. mdamian@cantacuzino.ro
authors.forename: Maria
authors.initials: M
authors.lastname: Damian
authors.forename: Codruţa-Romaniţa
authors.initials: CR
authors.lastname: Usein
authors.forename: Dorina
authors.initials: D
authors.lastname: Tatu-Chiţoiu
authors.forename: A M
authors.initials: AM
authors.lastname: Palade
authors.forename: Natalia
authors.initials: N
authors.lastname: Popovici
authors.forename: Simona
authors.initials: S
authors.lastname: Ciontea
authors.forename: Maria
authors.initials: M
authors.lastname: Nica
authors.forename: Laura
authors.initials: L
authors.lastname: Grigore
mesh_terms: D000328:Adult; D001422:Bacterial Adhesion / Q000235:genetics; D002353:Carrier State; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology / Q000517:prevention & control*; D029968:Escherichia coli Proteins / Q000235:genetics; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics; D005798:Genes, Bacterial; D006801:Humans; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D029968:Escherichia coli Proteins; D037521:Virulence Factors; D036781:Fimbriae Proteins