The MLVA Typing Analysis Of Shigella Sonnei Isolates From Some Regions In China

Shigella sonnei is a common food-borne pathogen, which had caused many outbreaks all over the world. It is an independent serum group of shigellae and only a serum type. PFGE typing method has widely applied in the analysis of Shigella sonnei. With the development of the second generation typing methods, MLVA typing was also used in molecular typing of Shigella sonnei. In order to analyse molecular epidemiology characteristics of Shigella sonnei in China, we applied MLVA including eight VNTRs to analyse 676 isolates from 12 regions of China.Through the analysing of 219 isolates from five outbreaks and 457 sporadic isolates, we found prevalent MLVA type isolates existed in the four outbreaks but not in another outbreak. The prevalent types were independent among the four outbreaks (ACDE), and the MLVA types of another outbreak(B) were scattered. The result of MLVA typing was relatively consistent with that of PFGE typing within the five outbreaks isolates. As a powerful molecular typing method, MLVA can be used in the investigation of the outbreak caused by Shigella sonnei. The analysis result of 457 sporadic isolates showed that there is no prevalent MLVA type Shigella sonnei isolates exist in all the 10 regions during 9 years in China, but there are prevalent types in some regions or years. Some prevalent types existed cross years or regionals. The prevalent MLVA types of C outbreak isolates also existed in the sporadic isolates in the same region and year. The rusult suggested that SS8.252 may be the prevalent type at the Gansu in 2007. The analysis of the sporadic isolates showed that MLVA typing had higher discrimination than PFGE typing. MLVA can differented the isolates with same PFGE patterns, which can provide molecular basis for analysing the relationship of isolates from different outbreaks and regions.As a simple, timely and labor saving molecular typing method, MLVA can be widely used in the molecular epidemiological analysis of Shigella sonnei, and to trace the source of isolates in the outbreak investigation in China.