Characterization of Isolates from Diseased Poultry in Northern China between 2014 and 2018.

infection not only causes acute and chronic diseases in poultry flocks, but the infected poultry are among the most important reservoirs for a variety of serovars frequently transmitted to humans. This study aimed to investigate the occurrence of spp. in local poultry farms in China. Samples (n = 4255), including dead-in-shell embryos, culled day-old-hatchings and 1- to 4-week-old diseased birds, were collected for culture from broiler chicken, meat-type duck and pigeon farms in northern China between 2014 and 2018. A total of 103 were isolated. serovar Enteritidis and Typhimurium were the most prevalent serovars, representing 53.4% and 34.9% of the isolates, respectively. Serovar diversity was the highest in ducks, with the Apeyeme being isolated for the first time from duck tissues. All isolates were characterized by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). MLST showed that all Enteritidis isolates shared the same sequence type (ST11), and Typhimurium showed several rare STs in addition to ST19. In comparison, PFGE showed better discrimination for Enteritidis and Typhimurium isolates, with nine distinct pulsotypes being observed. The isolates exhibited varying degrees of resistance to 15 tested antimicrobials and identified Enteritidis isolates (98.18%) with multiple antimicrobial resistance were a cause for concern. Our data on invasive infection in meat-type poultry in local farms can be used to identify sources and factors associated with spread in poultry and the associated food chain.