Changes in antimicrobial resistance patterns and dominance of extended spectrum β-lactamase genes among faecal Escherichia coli isolates from broilers and workers during two rearing periods

AbstractThe emergence of antibiotic-resistant Escherichia coli, especially extended–spectrum β-lactamase (ESBL)–producing strains, in the intestinal tract of broilers could be a threat to poultry and human. We investigated changes of antimicrobial resistance patterns and frequency of ESBL genes among faecal E. coli isolates of broilers and workers in five different farms during two rearing periods in Iran. In this regard, E. coli was isolated from rectal swabs of the workers and cloacal swabs of the broilers. After detection of antibiotic resistance patterns, phenotypic and genotypic characterisation of ESBL phenotype in these strains, carriage of the resistance genes on their crude plasmid extracts and diversity of plasmid profiles were analysed. Accordingly, multidrug-resistant (MDR) patterns were detected in a high percentage of E. coli strains from the workers (72.7%) and poultry (92.3%). ESBL-producing E. coli strains were identified in these farms throughout the two periods of rearing (6.3%). blaCTX...