Multiple-locus variable-number tandem-repeat analysis for discriminating within<i>Salmonella enterica</i>serovar Typhimurium definitive types and investigation of outbreaks

Dyet, Kristin; Turbitt, Erin; Carter, P. E.

doi:10.1017/s0950268810002025

Cited by 8 publications

(10 citation statements)

References 33 publications

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“…Despite of missing loci, 111 distinct MLVA types were observed. According to other studies, MLVA was highly discriminatory (DI > 0.9) for STM [ 30 , 42 ]. Low diversity observed, especially among the domestic DT1, might result from factors such as geographical isolation, endemic nature of the isolates and lacking of two loci (STTR6 and STTR10pl) in Finnish STM, rather than from the low discriminatory ability of MLVA method as such.…”

Section: Discussionmentioning

confidence: 59%

“…This is supported by the fact that the PFGE typing showed low diversity as well. The DT101 isolates in New Zealand [ 30 ] and the STM isolates in Malaysia [ 43 ] have also been shown to lack STTR6 and STTR10p loci.…”

Section: Discussionmentioning

confidence: 99%

“…These variable-number tandem repeat (VNTR) markers have been applied for typing and clustering of several Salmonella serotypes, for example, Dublin [ 20 ], Enteritidis [ 21 ], Gallinarum [ 22 ], Montevideo [ 23 ], Newport [ 24 ], Paratyphi A [ 25 ], Typhi [ 26 ] and Typhimurium [ 27 ]. MLVA typing has also been used successfully in several STM outbreak investigations [ 28 – 30 ]. Reduced typing time, easy handling and clearer interpretation of MLVA results, compared to those of PFGE, are beneficial in an outbreak situation.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

et al. 2015

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BackgroundSalmonella enterica spp. enterica serotype Typhimurium (STM) is the most common agent of domestically acquired salmonellosis in Finland. Subtyping methods which allow the characterization of STM are essential for effective laboratory-based STM surveillance and for recognition of outbreaks. This study describes the diversity of Finnish STM isolates using phage typing, antimicrobial susceptible testing, pulsed-field gel electrophoresis (PFGE) and multilocus variable-number tandem repeat analysis (MLVA), and compares the discriminatory power and the concordance of these methods.ResultsA total of 375 sporadic STM isolates were analysed. The isolates were divided into 31 definite phage (DT) types, dominated by DT1 (47 % of the isolates), U277 (9 % of the isolates) and DT104 (8 % of the isolates). Of all the isolates, 62 % were susceptible to all the 12 antimicrobials tested and 11 % were multidrug resistant. Subtyping resulted in 83 different XbaI-PFGE profiles and 111 MLVA types. The three most common XbaI-PFGE profiles (STYM1, STYM7 and STYM8) and one MLVA profile with three single locus variants accounted for 56 % and 49 % of the STM isolates, respectively. The studied isolates showed a genetic similarity of more than 70 % by XbaI-PFGE. In MLVA, 71 % of the isolates lacked STTR6 and 77 % missed STTR10p loci. Nevertheless, the calculated Simpson’s diversity index for XbaI-PFGE was 0.829 (95 % CI 0.792−0.865) and for MLVA 0.867 (95 % CI 0.835−0.898). However, the discriminatory power of the 5-loci MLVA varied among the phage types. The highest concordance of the results was found between XbaI-PFGE and phage typing (adjusted Wallace coefficient was 0.833 and adjusted Rand coefficient was 0.627).ConclusionsIn general, the calculated discriminatory power was higher for genotyping methods (MLVA and XbaI-PFGE) than for phenotyping methods (phage typing). Overall, comparable diversity indices were calculated for PFGE and MLVA (both DI > 0.8). However, MLVA was phage type dependent providing better discrimination of the most common phage types. Furthermore, 5-loci MLVA was a less laborious method and easier to interpret than XbaI-PFGE. Thus, the laboratory-based surveillance of the Finnish human STM infections has been conducted with a combination of phage typing, antimicrobial susceptibility testing and 5-loci MLVA since January 2014.

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Section: Discussionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

et al. 2015

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“…Since 2000 the two most frequently reported serotypes in Bulgaria are Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) and Salmonella Typhimurium (Anonymous, 2013;WHO 2014). Annually, a number of food-borne outbreaks linked to the consumption of different food of animal origin occur among humans worldwide (Dyet, Turbitt, & Carter, 2011). Recent studies also describe the occurrence of Salmonella contamination in food of nonanimal origin, for example, beans (Sadler-Reeves et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Use of multiple‐locus variable‐number of tandem repeats analysis (MLVA) to investigate genetic diversity of Salmonella enterica subsp. enterica serovar Typhimurium isolates from human, food, and veterinary sources

Mateva¹,

Pedersen

Sørensen

et al. 2017

MicrobiologyOpen

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Salmonella enterica subspecies enterica serovar Typhimurium is the most common zoonotic pathogen in Bulgaria. To allow efficient outbreak investigations and surveillance in the food chain, accurate and discriminatory methods for typing are needed. This study evaluated the use of multiple‐locus variable‐number of tandem repeats analysis (MLVA) and compared results with antimicrobial resistance (AMR) determinations for 100 S. Typhimurium strains isolated in Bulgaria during 2008–2012 (50 veterinary/food and 50 human isolates). Results showed that isolates were divided into 80 and 34 groups using MLVA and AMR, respectively. Simpson's index of diversity was determined to 0.994 ± 0.003 and 0.945 ± 0.012. The most frequently encountered MLVA profiles were 3‐11‐9‐NA‐211 (n = 5); 3‐12‐9‐NA‐211 (n = 3); 3‐12‐11‐21‐311 (n = 3); 3‐17‐10‐NA‐311 (n = 3); 2‐20‐9‐7‐212 (n = 3); and 2‐23‐NA‐NA‐111 (n = 3). No clustering of isolates related to susceptibility/resistance to antimicrobials, source of isolation, or year of isolation was observed. Some MLVA types were found in both human and veterinary/food isolates, indicating a possible route of transmission. A majority (83%) of the isolates were found to be resistant against at least one antimicrobial and 44% against ≥4 antimicrobials. Further studies are needed to verify MLVA usefulness over a longer period of time and with more isolates, including outbreak strains.

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“…However, when compared the subtyping approaches, MLVA displayed high diversity raising the possibilities to discriminate between and within diverse phage types and AMR types (Table 1 ). Several researches also related that STTR10 was the most variable locus followed by STTR5 and STTR6, and the least diversity was found in STTR3 and STTR9 (Dyet et al, 2011 ; García et al, 2013 ; Ido et al, 2015 ). Although theses researches had found variability in three of the five VNTR loci (STTR5, STTR6, and STTR3), MLVA proved to be efficient in distinguishing closely related S .…”

Section: Genotypic Methodsmentioning

confidence: 98%

Phenotypic and Genotypic Eligible Methods for Salmonella Typhimurium Source Tracking

2017

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Salmonellosis is one of the most common causes of foodborne infection and a leading cause of human gastroenteritis. Throughout the last decade, Salmonella enterica serotype Typhimurium (ST) has shown an increase report with the simultaneous emergence of multidrug-resistant isolates, as phage type DT104. Therefore, to successfully control this microorganism, it is important to attribute salmonellosis to the exact source. Studies of Salmonella source attribution have been performed to determine the main food/food-production animals involved, toward which, control efforts should be correctly directed. Hence, the election of a ST subtyping method depends on the particular problem that efforts must be directed, the resources and the data available. Generally, before choosing a molecular subtyping, phenotyping approaches such as serotyping, phage typing, and antimicrobial resistance profiling are implemented as a screening of an investigation, and the results are computed using frequency-matching models (i.e., Dutch, Hald and Asymmetric Island models). Actually, due to the advancement of molecular tools as PFGE, MLVA, MLST, CRISPR, and WGS more precise results have been obtained, but even with these technologies, there are still gaps to be elucidated. To address this issue, an important question needs to be answered: what are the currently suitable subtyping methods to source attribute ST. This review presents the most frequently applied subtyping methods used to characterize ST, analyses the major available microbial subtyping attribution models and ponders the use of conventional phenotyping methods, as well as, the most applied genotypic tools in the context of their potential applicability to investigates ST source tracking.

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Multiple-locus variable-number tandem-repeat analysis for discriminating withinSalmonella entericaserovar Typhimurium definitive types and investigation of outbreaks

Cited by 8 publications

References 33 publications

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

Characterization of Salmonella Typhimurium isolates from domestically acquired infections in Finland by phage typing, antimicrobial susceptibility testing, PFGE and MLVA

Use of multiple‐locus variable‐number of tandem repeats analysis (MLVA) to investigate genetic diversity of Salmonella enterica subsp. enterica serovar Typhimurium isolates from human, food, and veterinary sources

Phenotypic and Genotypic Eligible Methods for Salmonella Typhimurium Source Tracking

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