Serotype distribution characteristics and molecular typing of Salmonella in Yunnan Province from 2015 to 2017

Objective To study the serotype distribution characteristics and genotypes of Salmonella strains isolated in Yunnan Province from 2015 to 2017. Methods Automatic microbiological identification system and mass spectrometer were used to identify Salmonella strains. Their serotypes were detected using the White-Kauffmann-Le Minor (WKL) scheme based on serological detection. Genotyping was carried out by referring to the molecular typing method of Salmonella serotype pulse field gel electrophoresis (PFGE) in PulsenetChina. Cluster analysis was performed with Bionumerics (7.6). Results A total of 408 strains of Salmonella were detected in food and patients in Yunnan Province form 2015 to 2017, belonging to 70 serotypes. Thirty-four Salmonella derby strains were detected in food, accounting for 19.10% of all Salmonella strains detected in food. Among the Salmonella strains detected in patients, 71 were Salmonella enteritis and 67 were Salmonella typhimurium, accounting for 30.34% and 27.63%, respectively. Results of PFGE revealed that Salmonella derby and Salmonella typhimurium were polymorphic, and Salmonella enteritis had obvious advantages PFGE band patterns. No obvious time or geographical aggregation was found in the PFGE bands of the three Salmonella species. Conclusion Seventy Salmonella serotypes had been identified in Yunnan Province by 2017. Salmonella derby was the predominant serotype detected in food, while Salmonella enteritidis and Salmonella typhimurium were the predominant serotypes in patients. These three Salmonella species caused sporadic infections in Yunnan Province. Key words: Salmonella serotype; Salmonella derby; Salmonella enteritis; Salmonella typhimurium; Pulse field gel electrophoresis