The insertion sequence IS200 fingerprints chromosomal genotypes and epidemiological relationships in Salmonella heidelberg

Abstract

In Salmonella heidelberg the copy number of the Salmonella-specific insertion element IS200 was found to vary from four to six. All strains tested contained at least one common insertion site which was serovar specific, and most strains contained three common sites. Concurrent analysis of plasmids indicated that all insertion sequence copies were chromosomally located, and also supported the equivalence of an IS200 fingerprint and clonality. Seven intra-serovar clonal lines were thereby identified. One of these was associated with human infections, including septicaemias. Another was associated with chicken as a host: all these strains also carried a unique plasmid of 23 MDa, which was typed as a member of the IncX group. The chromosomal fingerprint of a third clone showed it to be a descendant of the chicken line marked by a single IS200 transposition. One or two representatives of four other clonal lines were identified. These lines of S. heidelberg could be related by divergent evolution, and the most recent relatives conformed to a continuous branching process model of IS200 transposition. This insertion sequence provided a highly discriminatory molecular marker of the S. heidelberg chromosome, and two of the seven clonal lines so identified were associated with distinct clinical/epidemiological contexts.

Molecular typing of Salmonella enterica subsp. enterica serovar Enteritidis isolates

“…This method was particularly helpful for serovars that usually harboured a large number of IS200 copies such as Typhimurium [15,29], Typhi [39], Paratyphi [40], Java [40] and Heidelberg [36]. In other serovars, such as Berta [37,38] and Enteritidis , its use for epidemiological typing was limited due to the low number of IS200 copies in these strains.…”

“…Traditional epidemiological studies included biochemical and serological characteristics of the Genotypic analysis of salmonellae by molecular typing methods has proved to be helpful in the characterisation of strains from different Salmonella serovars, such as S. Typhimurium [6,15,27,29], S. Enteritidis [6, 9-11,30-331, S. Dublin [24,34], S. Virchow [35], S. Heidelberg [36], S. Berta [37,38], S. Typhi [39], S. Paratyphi [40] and S. Java [40]. The techniques included plasmid analysis, ribotyping, IS200 typing and PFGE analysis.…”

IS200 fingerprint of Salmonella enterica serotype Typhimurium human strains isolated in Sardinia

“…The use of this insertion sequence epidemiologically and phylogenetically significant observations have been made in several salmonella serovars (i.e. Enteritidis, Bovismorbificans, Abortusovis, Heidelberg, Dublin,Typhimurium, Brandeburg, Typhi) [3,7,[9][10][11][12][13][14][15]. The element is also present in certain isolates of Shigella sp.…”

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

“…Analysis of the copy number and chromosomal loci of a Salmonella-specific DNA insertion element, IS200 (Lam & Roth, 1983a, b, 1986, has provided useful insights into evolutionary and epidemiological relationships of several Salmonella serovars of public health importance (Stanley et al, 1991(Stanley et al, , 1992(Stanley et al, , 1993Ezquerra et al, 1993). The objective of this study was to combine IS200 profiling with 16s rRNA gene profiling to analyse phylogenetic relationships within the S. paratyphi B/S.…”