Molecular typing of Salmonella paratyphi A strains isolated in Hangzhou area from 2002 to 2013 / 中华微生物学和免疫学杂志

ABSTRACT

Objective To analyze the molecular characteristics of Salmonella paratyphi A ( S. pa-ratyphi A) strains prevailing in Hangzhou area in recent years. Methods Pulse field gel electrophoresis ( PFGE) and multiple-locus variable-number tandem repeat analysis ( MLVA) were performed for molecular typing and epidemiological analysis of 72 S. paratyphi A strains isolated in Hangzhou area during 2002 to 2013. Results The 72 S. paratyphi A strains were divided into 11 PFGE ( by using restriction enzymes of Xba Ⅰ and Bln Ⅰ) and 6 MLVA types. Among the selected 34 variable number tandem repeat ( VNTR) sites, 4 sites (1188K, 2075K, 2201K and 4346K) showed high polymorphism, in which PFGE displayed a higher resolution than MLVA. Except for the 5 PFGE types of X4B5, X7B7, X8B8, X9B9 and X10B10, the other 6 PFGE types belonged to a same clone sharing a similarity of greater than 95%, and the S. Paratyphi A strains in that clone accounted for 93. 1% of the total strains isolated in Hangzhou. Conclu-sion The occurrence of paratyphoid A in Hangzhou area from 2002 to 2013 was mainly caused by S. para-typhi A strains belonging to the same clone. Combination of PFGE with MLVA was conducive to epidemiolog-ical investigation of paratyphoid A.