Antimicrobial resistance, virulence gene profiles, and phylogenetic groups of Escherichia coli isolated from healthy broilers and broilers with colibacillosis in Thailand

BackgroundMultidrug resistance in Escherichia coli has a significant global impact on poultry production. This study aimed to determine the phenotypic and genotypic backgrounds of antimicrobial resistance (AMR) and virulence gene profiles of E. coli strains isolated from diseased and healthy broilers. A total of 211 E. coli isolates were recovered from diseased (n = 110) and healthy broilers (n = 101). All the isolates were subjected to antimicrobial susceptibility testing. A PCR-based technique was applied to screen AMR genes, virulence genes and analyze phylogenetic groups.ResultsPhylogenetic groups B1 and D were the most prevalent for E. coli isolated from diseased and healthy birds. Among virulence genes, the detection rates of cva/cvi, iutA, iucD, iroN, iss and ompT were considerably greater in E.coli strains from diseased birds than in healthy birds. The virulence gene pattern of hlyF-iutA-iucD-iroN-iss-ompT (16.4%) was frequently observed in E.coli isolated from diseased birds, whereas approximately 22.8% of E.coli from healthy birds did not carry any virulence genes. Analysis of AMR profiles revealed that 58.3% of E.coli were resistant to multiple classes of antibiotics, and 96.7% carried at least one antibiotic resistance gene AMR genes.ConclusionThe findings of this study demonstrate the variable distribution of phylogenetic groups and virulence genes. E.coli strains isolated from broilers had multidrug resistance profiles. The study emphasizes the need for continuous monitoring of AMR emergence in E. coli from broilers. This monitoring allows for early detection and implementation of strategies to control the spread of resistant strains.