Niu, DongyanWang, Yanqi2024-01-092024-01-092024-01Wang, Y. (2024). Microbiological and molecular identification and characterization of avian pathogenic Escherichia coli from poultry farms, Alberta (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/117874https://doi.org/10.11575/PRISM/42717Avian pathogenic Escherichia coli (APEC) is the etiological agent of avian colibacillosis, leading to significant economic losses in Canada and elsewhere. Avian fecal E. coli (AFEC) is considered to serve as a potential reservoir for APEC given shared genetic features. This study aimed to profile phenotypic and genotypic features of causative APEC in Alberta. Here, 100 APEC isolates from diseased and dead chickens (broiler and layer) and turkeys from 45 farms collected between 2021 and 2023 were subjected to serogroup typing, APEC-associated virulence gene (VG) profiling, antimicrobial susceptibility testing, multilocus sequence typing, and phylogenetic analysis. In addition, 121 AFEC isolates from five layer flocks were collected to investigate APEC-associated VG carriage in healthy birds. Furthermore, genetic similarity between 22 AFEC strains identified as potential APEC (poAPEC) and APEC strains was assessed through phylogenetic analysis. We identified 27 serogroups, 38 known and two novel sequence types (STs), and varied VG distribution across APEC isolates from chickens and turkeys. Interestingly, variations in VG among AFEC strains were found across distinct egg laying stages or housing systems. Antimicrobial resistance (AMR) genes, especially extended-spectrum beta-lactamase genes were detected in APEC and poAPEC strains across all poultry species. Moreover, phylogenetic analysis revealed close clonal relationships among APEC and poAPEC strains. Notably, we identified a poAPEC isolate that shared ST155 and VGs with an APEC strain. This study is the first to report the characteristics of APEC and poAPEC isolates that cause or potentially cause colibacillosis morbidity and mortalities in chickens and turkeys in Alberta. A variety of APEC phenotypes and genotypes can lead to colibacillosis in poultry farms and may originate from the commensal E. coli found in the gastrointestinal tract of birds.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Avian Pathogenic Escherichia coliBioinformaticsMicrobiologyBiology--Molecularmaster thesis