Stability of Multiple-Locus Variable-Number Tandem Repeats in
            <i>Salmonella enterica</i>
            Serovar Typhimurium

Hopkins, Katie L.; Maguire, C.; Best, Emma L.; Liébana, Ernesto; Threlfall, E. John

doi:10.1128/jcm.00715-07

Cited by 42 publications

(42 citation statements)

References 14 publications

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“…Twenty isolates produced 1 of 3 related profi les (loci of VNTR profi les are ordered STTR9-STTR5-STTR6-STTR10pl-STTR3): 1-4-0-0-3, 9 isolates; 1-5-0-0-3, 3 isolates; or 1-6-0-0-3, 8 isolates. Alleles 4 and 5, and 5 and 6 at locus STTR5 only differed by an extra 6-bp repeat, which suggests a clonal relationship between the qnrS1-positive S. Typhimurium in this study (Table) (8). S. Typhimurium isolates with the 1-6-0-0-3 profi le have been isolated from tourists returning from Asia (7), which suggests that the UK qnrS1-positive S. Typhimurium isolates have originated in the Far East.…”

Section: Plasmid-mediated Quinolone Resistance In Salmonella Entericamentioning

confidence: 82%

Plasmid-mediated Quinolone Resistance inSalmonella enterica, United Kingdom

Hopkins¹,

Day²,

Threlfall³

2008

Emerg. Infect. Dis.

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Section: Plasmid-mediated Quinolone Resistance In Salmonella Entericamentioning

confidence: 82%

Plasmid-mediated Quinolone Resistance inSalmonella enterica, United Kingdom

Hopkins¹,

Day²,

Threlfall³

2008

Emerg. Infect. Dis.

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“…To accommodate such VOL. 47, 2009 MLVA FOR TYPING OF GLOBAL SEROVAR TYPHI ISOLATES 2371 on May 9, 2018 by guest http://jcm.asm.org/ variation for epidemiological typing, it has been suggested that a single locus variant may be classified as belonging to the same outbreak (9,22). The stability of TR1 and TR2 used in this study was tested in laboratory culture using four isolates by Liu et al (20).…”

Section: Resultsmentioning

confidence: 99%

“…However, a quickly evolving marker may vary during an outbreak, and such a marker may be considered unstable. SAL16 (STTR5) which was also used in the serovar Typhimurium MLVA scheme has been shown to vary in three of the eight different serovar Typhimurium outbreaks studied (9). To accommodate such VOL.…”

Section: Resultsmentioning

confidence: 99%

Multiple-Locus Variable-Number Tandem-Repeat Analysis of Salmonella enterica Serovar Typhi

Octavia

Lan

2009

J Clin Microbiol

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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.

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“…Furthermore, the technique can be multiplexed and automated and is conducive to rapid and relatively high-throughput strain typing. MLVA assays are relatively robust (5,(15)(16)(17) and, while not perfect, they can provide phylogenetic information even with a limited number of loci (13,18). While access to a sequenced genome dramatically speeds the ability to establish new assays (3), it is not a requisite to assay development.…”

mentioning

confidence: 99%

“…It is one of the most reproducible and highly discriminatory typing techniques and has been widely and successfully used for a variety of Salmonella enterica serovars (12,15); for many situations, PFGE is capable of discriminating between closely related strains. In addition, the use of the assay to analyze different serovars does not require a great deal of modification, as might be required with procedures that are dependent on PCR.…”

mentioning

confidence: 99%

Improved Identification of Epidemiologically Related Strains of Salmonella enterica by use of a Fusion Algorithm Based on Pulsed-Field Gel Electrophoresis and Multiple-Locus Variable-Number Tandem-Repeat Analysis

et al. 2010

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Pulsed-field gel electrophoresis (PFGE) and multiple-locus variable-number tandem-repeat analysis (MLVA) are used to assess genetic similarity between bacterial strains. There are cases, however, when neither of these methods quantifies genetic variation at a level of resolution that is well suited for studying the molecular epidemiology of bacterial pathogens. To improve estimates based on these methods, we propose a fusion algorithm that combines the information obtained from both PFGE and MLVA assays to assess epidemiological relationships. This involves generating distance matrices for PFGE data (Dice coefficients) and MLVA data (single-step stepwise-mutation model) and modifying the relative distances using the two different data types. We applied the algorithm to a set of Salmonella enterica serovar Typhimurium isolates collected from a wide range of sampling dates, locations, and host species. All three classification methods (PFGE only, MLVA only, and fusion) produced a similar pattern of clustering relative to groupings of common phage types, with the fusion results being slightly better. We then examined a group of serovar Newport isolates collected over a limited geographic and temporal scale and showed that the fusion of PFGE and MLVA data produced the best discrimination of isolates relative to a collection site (farm). Our analysis shows that the fusion of PFGE and MLVA data provides an improved ability to discriminate epidemiologically related isolates but provides only minor improvement in the discrimination of less related isolates.Salmonellosis is one of the most common food-borne diseases in the United States (5). Consequently, it is important to understand how Salmonella strains disseminate within and between reservoirs and environments. Many molecular typing tools have been used for this purpose (11). Of these methods, pulsed-field gel electrophoresis (PFGE) is considered by many to be the gold standard for strain typing, and variable-number tandem-repeat (VNTR) assays are powerful alternative or complementary typing tools (3,22). Both methods offer a high degree of genetic resolution for strain typing, depending on several factors.PFGE involves separating chromosomal DNA macro-restriction fragments by size, and strains are discriminated based on the resulting band pattern observed after electrophoresis has been completed. It is one of the most reproducible and highly discriminatory typing techniques and has been widely and successfully used for a variety of Salmonella enterica serovars (12, 15); for many situations, PFGE is capable of discriminating between closely related strains. In addition, the use of the assay to analyze different serovars does not require a great deal of modification, as might be required with procedures that are dependent on PCR. Difficulties arise when strains are very closely related (i.e., poor discrimination [18,27]) or when bands comigrate in the gel or identically sized bands represent completely different fragments of chromosomal DNA and thereby produce spurio...

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Stability of Multiple-Locus Variable-Number Tandem Repeats in Salmonella enterica Serovar Typhimurium

Cited by 42 publications

References 14 publications

Plasmid-mediated Quinolone Resistance inSalmonella enterica, United Kingdom

Plasmid-mediated Quinolone Resistance inSalmonella enterica, United Kingdom

Multiple-Locus Variable-Number Tandem-Repeat Analysis of Salmonella enterica Serovar Typhi

Improved Identification of Epidemiologically Related Strains of Salmonella enterica by use of a Fusion Algorithm Based on Pulsed-Field Gel Electrophoresis and Multiple-Locus Variable-Number Tandem-Repeat Analysis

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