Serotyping of Escherichia coli species isolated from broilers and determination of Colistin resistance

Abstract

Systemic infections by avian pathogenic Escherichia coli (APEC) are economically damaging to poultry industries Worldwide. E. coli strains of serotypes O1, O2, O18 and O78 are preferentially associated with avian colibacillosis. The rfb gene cluster that controls O antigen synthesis generally varies among different E. coli serotypes. In this study, the rfb gene clusters of E. coli serotypes O1, O2, O18 and O78 were characterized and compared, and it was also aimed to search for Colistin resistance on a molecular basis. For the research, 200 swab samples were taken from 200 chickens suspected of colibacillosis in broiler poultry farms located in the vicinity of Aydın, İzmir, and Manisa Provinces in Turkey 2022. Bacterial growth was obtained from 92% of the samples, and microbiological analysis identified 108 (54%) Escherichia coli isolates. In addition, Klebsiella spp. was identified in 35 (17.5%) samples, Proteus spp. in 23 (11.5%), Pseudomonas spp. in 18 (9%), and no bacterial growth was observed in 16 (8%) samples. mcr-1 (309 bp) and mcr–2 (567 bp) genes responsible for Colistin resistance was investigated in plasmid DNA extracted from 108 E. coli isolates obtained in the study, using the PCR method. However, neither mcr-1 nor mcr–2 genes were detected in any of the samples. In conclusion, the allele-specific PCR method was found sensitive and applicable for APEC identification and multiple drug resistance emerged in E. coli strains isolated according to the antibiogram results.