Phenotype And Genotype Analysis Of Vibrio Parahaemolyticus,Salmonella And Cronobacter In Xiamen

Background: Vibrio parahaemolyticus and salmonella are common pathogens causing intestinal infections,and often cause large-scale foodborne outbreaks,Population infected by Cronobacter spp.are minority and case reports in the domestic are relatively rare,but because it can cause severe or lethal infections in infants and young children,so it had attracted great attention from domestic and overseas.Objective: To investigate the genotyping of Vibrio parahaemolyticus,Salmonella and Cronobacter spp.and the serotyping of Vibrio parahaemolyticus and Salmonella in Xiamen,and to reveal the main genotypes and serotypes of the three pathogenic bacteria in this area.To establish genotyping database and analyze the homology of strains from different sources,and to provide basic data for the source trace of outbreaks and early warning of the disease.Method: 309 strains of Vibrio parahaemolyticus,139 strains of Salmonella and 21 strains of Cronobacter were analyzed by pulse field gel electrophoresis(PFGE).Isolates of Vibrio parahaemolyticus were from 268 food samples and 141 food poisoning samples,and Salmonella strains isolated from 52 food poisoning samples,19 food strains,64 clinical specimens and 4 outer environment samples.Restriction electrophoresis profiles were imported into BioNumerics software for cluster analysis.At the same time,serotyping of Vibrio parahaemolyticus strains and Salmonella strains were performed according to GB 4789.7-2013 and GB 4789.4-2016.Result: In Xiamen,Vibrio parahaemolyticus food poisoning strains were typed into 20 serotypes,and O3:K6 accounting for 53.19%(75/141)was the main serotype and appeared almost every year.309 strains of Vibrio parahaemolyticus were digested with sfi? and 243 PFGE patterns were obtained by PFGE assay.The dominant pattern was PT162 generated by food poisoning isolates.Similarity value of all strains ranged from 31.5% to 100%,and they could be divided into seven large clusters except two isolates.The same cluster included food poisoning strains,environmental strains and ordinary aquatic product strains.Isolates from different types of aquatic prossessed distinct PFGE patterns.The similarity value between environment isolates and aquatic isolates from the same sea area was less than 85%.Except for 4 isolates of salmonella,the other 135 strains can be divided into 18 serotypes,and Salmonella enteritidis mainly from food poisoning specimens was the dominant serotype,accounting for 40.29%(56/139).139 strains were digested with Xba? and 63 PFGE patern were obtained by PFGE method.The similarity value was ranged from 53.7% to 100%,and the predominant pattern was PT51 generated by Salmonella enteritidis.Food poisoning strains was comprised of only 5 different patterns.Most of the strains of Salmonella enteritidis had high similarity value,and some food isolates,food poisoning isolates and foodborne disease surveillance isolates had exactly the same restriction map.Most of 21 strains of Cronobacter were from infant rice flour.The DNA was digested with Xba? and then subjected to PFGE assay.16 PFGE profiles was showed up.Except for two strains from G brand and C brand had indiscriminate PFGE pattern,the similarity value between different brand isolates was generally low,and the isolates from the same brand in different years could have identical PFGE pattern.Conclusion: Serotypes of Vibrio parahaemolyticus and Salmonella that caused food poisoning in Xiamen were multiple diverse,and the main serotypes was O3:K6 and Salmonella enteritidis,and the main bands was PT51 and PT162,respectively.The molecular typing results of the three kinds of pathogens presented diversity,but the number of PFGE patterns for food poisoning strains were few relatively.The isolates from the same food poisoning event had a high similarity,and the isolates from different food poisoning event might also prossessed a same PFGE pattern.Cronobacter could persist in the production environment.Cronobacter isolates from different brands might come from the same source of pollution.The molecular typing database of this research could be used in traceability studies of food-borne illnesses and hint potential outbreaks in routine surveillance in Xiamen.