Multiple-locus variable number of tandem repeats analysis of Salmonella enterica serotype paratyphi A from Yuxi and comparison with isolates from the Chinese Medical Culture Collection Center

The aim of the present study was to genotype Salmonella enterica serotype paratyphi A (SPA) isolated from Yuxi, China, in a multiple-locus variable number of tandem repeats (VNTRs) analysis (MLVA) and to compare them with isolates from the Chinese Medical Culture Collection Center (CMCC). Potential VNTRs were screened from the genomes of ATCC9150 and AKU_12601 using the Tandem Repeats Finder program. Nine VNTRs were established for MLVA typing of 195 SPA isolates from Yuxi and 20 isolates from CMCC. The dendogram for MLVA profiles and minimum spanning tree (MST) were drawn using the categorical coefficient calculated by BioNumerics software. A total of 23 MLVA types were identified in 215 SPA isolates and were grouped into six distinct cluster groups A, B, C, D, E and F. A total of 195 Yuxi SPA isolates were exclusively grouped into cluster C with nine MLVA genotypes. A total of 20 CMCC isolates were grouped in clusters A B, D, E and F with the other 14 MLVA types. The MLVA with nine VNTR loci, which was exploited in the present study, represents a successful strategy for genotyping SPA. Furthermore, the 195 Yuxi isolates appear to be closely related to each other and distinct from the 20 CMCC strains.