Putative enteroaggregative virulence and multidrug-resistance genes in Escherichia coli isolated from poultry in Algeria

Introduction. Enteroaggregative Escherichia coli (EAEC) is an important agent of persistent diarrhoea in the developing world and of outbreaks of diarrhoea in the developed world. Several virulence factors such as aggA, aggR and aap are important in EAEC adherence to the intestinal mucosa and in stimulating biofilm formation. Several other genes, including aatA, pet, ShET1, astA, irp2 and shf are also thought to be involved in EAEC pathogenesis. The aim of this study was to evaluate the enteroaggregative virulence genes in multi-drug resistant E. coli strains isolated from healthy broiler chicken and egg samples in Western Algeria. Materials and Methods. A total of 47 Escherichia coli strains isolated from healthy broiler chickens and eggs, collected from Western Algeria, were analyzed regarding the presence of EAEC virulence genes (aggR, aap, aatA, astA, pet, shf, irp2, set1A) by polymerase chain reaction. Phylogenetic groups were assigned by a multiplex PCR detecting the genes chuA, a gene required for heme transport in enterohemorrhagic E. coli O157:H7, yjaA stress-induced protein and DNA fragment TspE4.C2, codifying a lipase. Results. E. coli strains from chicken carried the EAEC probe sequence. Among these, two was AggR, astA and irp2 probe positive strains, 9 was astA+ and 10 was irp2+. None of egg samples showed enteroaggregative virulence genes. The strains were identified mainly as phylogroup A, the most frequent commensal E. coli strains, 4 strains as B1 and one as E. Discussion and Conclusions. Our data clearly indicates that the EAEC strains isolated from healthy broiler chicken samples present heterogenous combinations of putative enteroaggregative virulence genes. The AggR gene, important virulence factor in EAEC adherence to the intestinal mucosa, associated with irp2 (yersiniabactin biosynthesis gene) and astA (gene encoding enteroaggregative heat-stable toxin 1, EAST-1) was harbored in two strains. The irp2 and astA genes were both expressed in only one strain. Previously our study showed the resistance of the same strains to many of these drugs: nalidix acid, ciprofloxacin, amoxicillin, amoxicillin+clavulanic, cefotaxime, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, neomycin, colistin and imipenem. Among these, six cefotaxime resistant strains expressed ESBL genes. Taken together all these results showed the coexistence of ESBL and virulence genes. Particularly, two strains (group B1 and E) harbored irp2 and TEM, one (group B1) irp2, TEM and CTX-M-1, two (group A) astA and TEM and one (group F) was carrying simultaneously astA, irp2 and TEM. In conclusion, this study revealed the presence of putative enteroaggregative virulence genes in multidrug resistant E. coli strains isolated from poultry.