Application of Pulsed Field Electrophoresis and Plasmid Profile on Molecular Epidemiological Survey of Paratyphoid A Strain in Zhejiang Province

Objective This study aimed tO find the characteristics and molecular heterogeneity of the epidemic Paratyphoid A strain in Zhejiang Province through an approach of molecular biol-ogy．Methods A drug sensitive test for 26 fulminant and sporadic strains of Paratyphoid A in Zhejiang Province was conducted，a small amount of plasmid was extracted through a rapid method and a profile analysis was done，and at the same time，the gene maps of fulminant and sporadic strains were analyzed and compared through pulsed field gel electrophoresis (PEGE) technology．Results The drug resistance rates of the 26 strains to SM and CAR are higher than 52.00％．tO COS and AMP higher than 84.00％，and to SD higher than 100.00％．All the strains contain plasmid of-2.3Kb and-23.1Kb．After XbaI enzyme cutting，PFGE analysis was done，and the Macrorestricfion Map of chromosome for all strains showed 19 to 21 strips，and there are four types of strips for the 26 strains．The difference of strips numbers between any two of the strains is only 1-2．Conclusion Generally，the strains of Paratyphoid A in Zhejiang Province have plasmid，and most of the strains are of multiple drug resistance．Maybe this is relevant to the durative high incidence of Paratyphoid A in Zhejiang Province．PFGE analysis found that all strains were of the same clone family and relevant to some extent．This showed that the epidemic strains of Paratyphoid A in Zhejiang Province are conservative relatively．