Comparison of prevalence of avian pathogenic Escherichia coli in South African and US poultry

Abstract

Avian pathogenic Escherichia coli (APEC) as the etiological agent for Colibacillosis has extensively been described, with numerous research papers dissecting and elaborating on the prevalence and population dynamics of APEC throughout the world. The South African landscape however has not been elucidated to the same extent. In this study, 3025 South African E. coli samples were analysed for the period 2017 – 2022. Data were also analysed to compare the prevalence of APEC in the United States of America (USA) versus South Africa (SA). The USA isolates were all from broiler operations, with SA isolates from different operations. The study investigated the prevalence of APEC in SA, whether population differences occur for specific virulence - associated genes (VAGs) between operations, as well as the possible differences of virulence - associated gene (VAG) prevalence over time (2017 – 2022) within SA. The data available were also analysed to establish the potential difference of VAG prevalence between SA and USA. The extracted DNA was screened by a multiplex PCR for five APEC VAGs (cvaC, iss, iucC, tsh and irp2). The pathogenicity of each isolate was determined by comparing the number of genes detected in each isolate to a positive control. Isolates with two or more virulence genes were considered APEC positive. This research provides supporting evidence for the theory that geographical and environmental factors influence the genetic diversity and subsequent virulence of APEC. It would therefore suggest that prophylactic measures would need to be tailored to regional needs as required by each operation for a specific period in time.