Investigation of the phylogenetic groups, pathotypes, and clonality of extended spectrum β-lactamase encoding Escherichia coli strains in the intestine of broilers during rearing periods

Abstract

The emergence of extended spectrum β-lactamase (ESBL) among pathogenic Escherichia coli (E. coli) strains could be a threat to poultry and humans. This study aimed to investigate the diversity of ESBL genes among different phylogenetic groups (A, B1, B2, D) and pathotypes of E. coli strains (Shiga toxin producing E. coli, enteroinvasive E. coli, enteropathogenic E. coli, enterotoxigenic E. coli) in the intestines of chicken during the rearing period. PCR was done to characterize the phylogenetic groups, pathotypes, and blaTEM, blaSHV, and blaCTX genes. The homology of E. coli strains with ESBL-resistance pattern was analyzed by random amplification of polymorphic DNA-PCR and biotyping methods. In total, 6.3% (28/444) of the strains presented the ESBL phenotype, where carriage of blaCTX-M-1, blaCTX-M-61, blaTEM-116, and blaTEM-1 was confirmed after sequencing of the PCR products. Phylogenetic group D was the most prevalent phylogenetic group among ESBL-producing E. coli strains (42.85%), followed by group B1 (32.15%), group A (17.85%) and group B2 (7.15%). Two ESBL producing E. coli strains belonged to shiga toxin-producing E. coli (STEC) and one to atypical enteropathogenic E. coli (AEPEC) pathotypes. While identical RAPD-PCR and resistance profiles were detected among ESBL-producing strains in some of the poultry houses during the rearing period, this similarity was not confirmed among different farms. In conclusion, our results showed the presence and gradual dissemination of ESBL producing E. coli strains with pathogenic capacity for humans as well as poultry.