Detection of extended spectrum β-lactamase producing E. coli from broiler chickens

Abstract:

[Objective] We detected and analyzed β-lactam resistance in E. coli in broiler chickens in Shandong province. [Methods] The viscera samples were obtained from broiler chickens in the slaughterhouse. We screened β-lactam resistant E. coli, used the disk diffusion assay to determine antimicrobial-resistance, extracted bacterial DNA, conducted phylogenetic and biochemical assays, identified β-lactam-resistance genes and the structure of integrons and performed conjugation assays. [Results] More than 80% isolates were resistant to 3 or more β-lactams. The bla_TEM and bla_CTX-M resistance genes encoding class A β-lactamases have a higher rate, 86.7% and 81%, respectively, but only bla_CTX-M and β-lactam resistance showed a significant correlation. The rate of β-lactam resistance genes in B₁ and D₂ subtypes of E. coli was higher, and the resistance was significantly enhanced, while the A₀ and A₁ subtypes were more sensitive. Although integrons were commonly detected in E. coli, their correlation with β-lactamase genes is low. [Conclusion] The results show that broiler-derived E. coli has highly resistant to β-lactams, and multi-drug resistance is widespread. The relationship between the resistance of β-lactams and the phylogeny in E. coli is clarified, and it provides a reference for the epidemiological surveillance of β-lactam resistance in E. coli from broilers.