Salmonella reference collection B (SARB): strains of 37 serovars of subspecies I

Abstract

A reference collection of 72 strains representing 37 serovars of Salmonella subspecies I has been established for use in research on genetic and phenotypic variation in natural populations. Included are isolates of the host-adapted serovars S. choleraesuis, S. dublin, S. gallinarum, S. paratyphi A , S. paratyphi B, S. paratyphi C, S. pullorum, S. sendai, S. typhi and S. typhisuis, as well as strains of S. enteritidis, S. typhimurium, and other commonly recovered serovars with broad host ranges. The isolates were characterized by enzyme electrophoresis for allelic variation in 25 chromosomal genes and represent 71 distinctive multilocus genotypes (electrophoretic types or ETs). Genetic relationships among the ETs are indicated in an evolutionary tree constructed by the neighbourjoining method from a matrix of Nei's standard genetic distance.

Application of ribotyping and IS200 fingerprinting to distinguish the five Salmonella serotype O6,7[ratio ]c[ratio ]1,5 groups: Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C, and Typhisuis

“…The results of tests for biochemical activities, 16S rrn profile, rate of phase change and presence of IS200 are recorded in Table 1, in which strains are placed in groups according to our results. These indicated reassignment of two SARB strains to serotypes other than those shown [6].…”

“…Some of these strains, indicated with the suffix K in Table 1, are from the Kauffmann collection and may be considered the ' type ' strains of the group concerned. We examined all the strains of antigenic formula O6,7 : c : 1,5 included in the SARB collection [6]. This collection includes, for many serotypes, one strain of the electrotype most commonly encountered in that group and one representative of one or more of the less common electrotypes in the serotype.…”

Host adapted serotypes of Salmonella enterica

“…This group of serotypes includes the swine-adapted Choleraesuis, the swine-restricted serotype Typhisuis, and the human-restricted Paratyphi C. Typhisuis has been reported to be polyphyletic by MLEE analysis, with clone Ts3 genotypically related to Decatur (also with serotype O: 6,7 : c : 1,5) and very different from Ts1 and Ts2 [24,37]. However, in a more recent study based on ribotyping, IS200 fingerprinting, and biochemical analysis, Ts3 was reclassified as Decatur [38].…”

“…Thus, Typhisuis is strongly homogeneous and supports the argument that HR serotypes are less diverse than those that are pathogenic for a wide variety of animal hosts. Furthermore, Typhisuis appeared to be allied to Choleraesuis and to certain clones of Paratyphi C [37,38]. It has been suggested that these serotypes evolved from a common ancestor that was already capable of systemic infection and adapted to swine and that the acquisition of the Vi antigen by Paratyphi C allowed this serotype to adapt to humans [24].…”

“…Choleraesuis clones listed in the Salmonella reference collection B (SARB) comprise a predominant, widely distributed clone, of electrotype Cs1, and 3 other (Cs6, Cs11, and Cs13) much less common electrotypes [37]. Uzzau and colleagues observed that Choleraesuis and its Kunzendorf variant had related but distinct ribotypes [38].…”