Dataset Information

Multiple-locus variable-number tandem-repeat analysis of Salmonella enterica serovar Typhi.

ABSTRACT: Multilocus variable-number tandem repeats (VNTRs) are widely used as molecular markers to differentiate isolates of homogenous pathogenic clones. We explored the genomes of Salmonella enterica serovar Typhi strains CT18 and Ty2 for potential VNTRs. Among the 43 potential VNTRs screened, 2 were found to be polymorphic. Together with seven polymorphic VNTRs from previous studies, they were used to type 73 global serovar Typhi isolates. A total of 70 multilocus VNTR analysis (MLVA) profiles were found, distinguishing all except three pairs of isolates into individual profiles. The discriminatory power was 0.999. Phylogenetic analysis showed that the MLVA profiles can be divided into seven clusters. However, except for the closely related isolates, the relationships derived were in conflict with those inferred from single nucleotide polymorphism (SNP) typing using 38 SNPs done previously. We concluded that MLVA can resolve the relationships only among closely related isolates. A combination of SNP typing and MLVA typing offers the best approach for local and global epidemiology and the evolutionary analysis of serovar Typhi. We suggest that seven of the nine most polymorphic VNTRs be used as a standardized typing scheme for epidemiological typing.

SUBMITTER: Octavia S

PROVIDER: S-EPMC2725683 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature

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Multiple-locus variable-number tandem-repeat analysis of Salmonella enterica serovar Typhi.

Octavia Sophie S Lan Ruiting R

Journal of clinical microbiology 20090617 8

Multilocus variable-number tandem repeats (VNTRs) are widely used as molecular markers to differentiate isolates of homogenous pathogenic clones. We explored the genomes of Salmonella enterica serovar Typhi strains CT18 and Ty2 for potential VNTRs. Among the 43 potential VNTRs screened, 2 were found to be polymorphic. Together with seven polymorphic VNTRs from previous studies, they were used to type 73 global serovar Typhi isolates. A total of 70 multilocus VNTR analysis (MLVA) profiles were fo ...[more]

PMID: 19535521

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Project description:BACKGROUND: Prospective typing of Salmonella enterica serovar Typhimurium (STM) by multiple-locus variable-number tandem-repeat analysis (MLVA) can assist in identifying clusters of STM cases that might otherwise have gone unrecognised, as well as sources of sporadic and outbreak cases. This paper describes the dynamics of human STM infection in a prospective study of STM MLVA typing for public health surveillance. METHODS: During a three-year period between August 2007 and September 2010 all confirmed STM isolates were fingerprinted using MLVA as part of the New South Wales (NSW) state public health surveillance program. RESULTS: A total of 4,920 STM isolates were typed and a subset of 4,377 human isolates was included in the analysis. The STM spectrum was dominated by a small number of phage types, including DT170 (44.6% of all isolates), DT135 (13.9%), DT9 (10.8%), DT44 (4.5%) and DT126 (4.5%). There was a difference in the discriminatory power of MLVA types within endemic phage types: Simpson's index of diversity ranged from 0.109 and 0.113 for DTs 9 and 135 to 0.172 and 0.269 for DTs 170 and 44, respectively. 66 distinct STM clusters were observed ranging in size from 5 to 180 cases and in duration from 4 weeks to 25 weeks. 43 clusters had novel MLVA types and 23 represented recurrences of previously recorded MLVA types. The diversity of the STM population remained relatively constant over time. The gradual increase in the number of STM cases during the study was not related to significant changes in the number of clusters or their size. 667 different MLVA types or patterns were observed. CONCLUSIONS: Prospective MLVA typing of STM allows the detection of community outbreaks and demonstrates the sustained level of STM diversity that accompanies the increasing incidence of human STM infections. The monitoring of novel and persistent MLVA types offers a new benchmark for STM surveillance.A part of this study was presented at the MEEGID × (Molecular Epidemiology and Evolutionary Genetics of Infectious Diseases) Conference, 3-5 November 2010, Amsterdam, The Netherlands.

Dataset Information

Multiple-locus variable-number tandem-repeat analysis of Salmonella enterica serovar Typhi.

Publications

Multiple-locus variable-number tandem-repeat analysis of Salmonella enterica serovar Typhi.

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