Outbreak of Colibacillosis in Intensive Chicken Farms: Pathogenicity and
Molecular Characterization
Abstract
Avian pathogenic E. coli (APEC) are generally considered to be the
reservoir for human extraintestinal pathogenic E. coli (ExPEC): they
share similar genetic characteristics and pathogenicity with no or
minimal host specificity. In this study, we successfully isolated and
identified an E. coli strain as the culprit responsible for serious
colibacillosis outbreaks in intensive chicken farms in China in 2016. We
investigated its phylogenetic classification (A, B1, B2, C, D, E, and F)
by PCR analysis; its virulence and host range using challenge
experiments with different animals; and its virulence factors, drug
resistance genes, sequence type (ST), and related biological information
through high-throughput sequencing. This isolate was found to belong to
ST95, group B2, and serotype O18. The E. coli strain shows strong
virulence in chickens with a minimum lethal dose (MLD) of 3 × 103
CFU/chicken and a strong virulence in mice with an MLD of 3 × 102
CFU/mouse and in rabbits with an MLD of 3 × 103 CFU/rabbit. Whole-genome
sequencing showed that it consists of six types of prevalent resistance
genes, 33 antibiotic efflux genes, and nine recognized virulent factors.
The detailed data are available from GenBank (SRR13005645) for further
study.