Abstract
The virulence, serotype and phylogenetic traits of diarrhoeagenic Escherichia coli were detected in 502 strains isolated during digestive infections. Molecular detection of the target virulence genes, rfb gene of operon O and phylogenetic grouping genes Chua, yjaA and TSPE4.C2 was performed. Prevalence of strains harbouring virulent genes was 7.8%. The virulent genes eaeA, bfp, stx2, st1, lt, aggA, east1, ipaH, ial, cnf1 and afa were detected. EAEC (36%) and both EPEC and ATEC (25.6%) are the most detected pathovars (p<0.05). STEC (5.1%), NFEC (7.7) and DAEC (7.7) are less represented. Serogroups are overall diversified (89%), however, serogroups O157, O103 and O86, previously known to be associated with virulence were revealed. Most of the E. coli pathovars (53%) belonged to phylogenetic group A and in decreasing importance order, to D (23.5%), B1 (11.7%) and B2 (11.7%) groups. The study shows a diversified population of intestinal strains (84.6%), with a low phenotypic and phylogenetic link lower (p<0.05). Due to the great diversity of pathotypes, continuous monitoring should be implemented to identify risk factors and major pathways of contamination that help defining strategies to reduce infections associated with E. coli. Key words: Escherichia coli, virulence gene, serogroup, phylogenetic group, diversity.
Highlights
Escherichia coli are known as a component of the intestinal microflora of humans and most homeothermic or warm-blooded animals (Bettelheim, 1997)
The results showed the presence of stx2 genes, ial, ipaH, afa and cnf1 that are respectively some characteristic pathovars of Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), diffusely adherent E. coli (DAEC) and necrotizing factor producing E. coli (NFEC)
Eight of nine pathovars known as agents associated with diarrheas caused by pathogenic E. coli were detected
Summary
Escherichia coli are known as a component of the intestinal microflora of humans and most homeothermic or warm-blooded animals (Bettelheim, 1997). Strains that have acquired virulence factors are involved in digestive and extra-intestinal infections (Donnenberg, 2002). The epidemiological significance of virulent E. coli is well known and of public health concern (EFSA, 2011, 2012). The most recent outbreak occurred in Germany, and has spread in many countries of the European Union (Bielaszewska et al, 2011; Frank et al, 2011).
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