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Objective To study the serotype distribution characteristics and genotypes of Salmo-nella strains isolated in Yunnan Province from 2015 to 2017. Methods Automatic microbiological identifi-cation 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 car-ried 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,belong-ing 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 en-teritis 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 iden-tified 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.
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Objective To analyze the pulse-field gel electrophoresis (PFGE) patterns and antibiotic resistance of Salmonella enteritidisstrains isolated in Longyan city in order to provide reference for effective control, clinical diagnosis and treatment of outbreaks of food-borne diseases.Methods Seventy-seven Salmonella enteritidis strains isolated from food poisoning cases, livestock and poultry meat samples collected for food safety risk monitoring and sporadic cases in 2014 and 2016 were analyzed by PFGE.Antibiotic susceptibility testing was carried out to determine the minimum inhibitory concentrations (MIC) of 16 common antibiotics to 57 strains.Results Seventeen PFGE types were identified among the 77 Salmonella strains including three predominant types (P4, P6 and P8) and were grouped into three major pulsotypes (Cluster1-3) at 90% similarity level.The predominant types causing outbreaks of Salmonella enteritidis infection were P8, P6, P4 and P14, which were responsible for five cases of food poisoning.These isolated strains were highly resistant to nalidixic acid (93%), followed by resistance towards ampicillin (74%) and streptomycin (54%).Forty-one strains were resistant to three or more antibiotics (71.93%).Conclusion The PFGE types of Salmonella enteritidis strains isolated in Longyan city exhibit polymorphism and are clustered into three major pulsotypes.PFGE molecular typing can provide early-warning of sporadic outbreaks and help to identify the sources of infections in Salmonella enteritidis-related food poisoning.Attentions should be paid to multidrug resistant Salmonella enteritidis.Surveillance for multidrug resistant strains and usage of antibiotics should be strengthened.