Epidemiological characteristics of Salmonella in Shanghai.

To study the epidemiological characteristics of Salmonella thompson (S. thompson) outbreak isolates in Shanghai Huangpu district, the isolates from sporadic and outbreak diarrhea cases in WHO Global Salm-Surv (GSS) were collected and the phenotype confirmation and antibiotic resistance were identified. XbaⅠrestriction enzyme was used for PFGE and BioNumerics 4.0 software was used to conduct cluster analysis for results analyzing. Ranking third in clinical isolates of non-typhoidal Salmonella in Shanghai, 22 strains of S. thompson were separated from diarrhea patients in GSS 2007. The 8 S. thompson strains isolated from clustered cases of diarrhea in Huangpu district central hospital in 2007 were 100% resisted to Tetracycline, Augmentin, Ampicillin, Chloramphenicol, Nalidixic acid and Sulfafurazole, which indicated that the drug resistance of S. thompson strains was much higher than that of the sporadic strains. All the 20 strains from patients and 2 food-borne strains were divided into 15 subtypes by PFGE, and then 8 outbreak isolates strains from patients showed homologous graphics in PFGE. The other 12 sporadic strains and the 2 food-borne strains showed different subtypes in PFGE, and there was no genetic homology among them. Results demonstrated that the outbreak case in a construction site in Shanghai Huangpu district in 2007 was occurred by multiple-resistance clone strains of S. thompson, and indicated that PFGE could confirmed the local outbreak cases by molecular homology of strains.