Genotypic typing and phylogenetic analysis of Salmonella paratyphi B and S. java with IS200

Salmonella paratyphi B and Salmonella java are biovars of common serotype 1,4,[5],12:b:1,2 which respectively cause human paratyphoid fever and gastroenteritis. In order to define genotypes and phylogenetic relationships in this group, we examined representative strains for restriction fragment length polymorphisms (RFLPs) in and around the 16S ribosomal RNA (rrn) genes, and the five to eleven insertion sites of the Salmonella-specific DNA insertion sequence IS200. One of four 16S rrn profiles was predominant, and was shared by the majority of strains, irrespective of their designation as S. paratyphi B or S. java. On the other hand, thirteen unique IS200 profiles were found and this technique was able to distinguish, for the first time, distinct genotypes for S. paratyphi B and S. java. One of the S. paratyphi B profiles, Spj-IP1.0, represented a globally-distributed clone. Greater diversity was detected within IS200 profiles of S. java than within those of S. paratyphi B. IS200 profiles described a phylogenetic complex in which strains of both biovars could be placed. They constituted reproducible molecular fingerprints, which could be compared in a band-matching database suitable for molecular epidemiological typing.