Outbreak of Salmonella Typhimurium infection traced to imported cured sausage using MLVA-subtyping

Nygård, Karin; Lindstedt, Bjørn-Arne; Wahl, W; Jensvoll, Laila; Kjelsø, Charlotte; Mølbak, Kåre; Torpdahl, Mia; Kapperud, Georg

doi:10.2807/esw.12.11.03158-en

Cited by 14 publications

(14 citation statements)

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“…Clustering confirmed by both subtyping methods provides strong evidence for true genetic relatedness, while discordant results can be difficult to interpret. Similar to our study which suggested diversification of both PFGE and MLVA patterns on individual farms, the diversification of PFGE and MLVA patterns has been reported during human salmonellosis outbreaks, even though diversification rates are difficult to estimate (23,50,64,67). In such instances, the use of additional information, e.g., epidemiologic data, antimicrobial resistance patterns, or prior knowledge of subtype diversity, can be very useful for inferring relationships between isolates.…”

Section: Discussionsupporting

confidence: 82%

The Prevalence of Multidrug Resistance Is Higher among Bovine than HumanSalmonellaentericaSerotype Newport, Typhimurium, and 4,5,12:i:− Isolates in the United States but Differs by Serotype and Geographic Region

Hoelzer

Soyer

Rodriguez‐Rivera

et al. 2010

Appl Environ Microbiol

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Salmonella represents an important zoonotic pathogen worldwide, but the transmission dynamics between humans and animals as well as within animal populations are incompletely understood. We characterized Salmonella isolates from cattle and humans in two geographic regions of the United States, the Pacific Northwest and the Northeast, using three common subtyping methods (pulsed-field gel electrophoresis [PFGE], multilocus variable number of tandem repeat analysis [MLVA], and multilocus sequence typing [MLST]). In addition, we analyzed the distribution of antimicrobial resistance among human and cattle Salmonella isolates from the two study areas and characterized Salmonella persistence on individual dairy farms. For both Salmonella enterica subsp. enterica serotypes Newport and Typhimurium, we found multidrug resistance to be significantly associated with bovine origin of isolates, with the odds of multidrug resistance for Newport isolates from cattle approximately 18 times higher than for Newport isolates from humans. Isolates from the Northwest were significantly more likely to be multidrug resistant than those from the Northeast, and susceptible and resistant isolates appeared to represent distinct Salmonella subtypes. We detected evidence for strain diversification during Salmonella persistence on farms, which included changes in antimicrobial resistance as well as genetic changes manifested in PFGE and MLVA pattern shifts. While discriminatory power was serotype dependent, the combination of PFGE data with either MLVA or resistance typing data consistently allowed for improved subtype discrimination. Our results are consistent with the idea that cattle are an important reservoir of multidrug-resistant Salmonella infections in humans. In addition, the study provides evidence for the value of including antimicrobial resistance data in epidemiological investigations and highlights the benefits and potential problems of combining subtyping methods.

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Section: Discussionsupporting

confidence: 82%

The Prevalence of Multidrug Resistance Is Higher among Bovine than HumanSalmonellaentericaSerotype Newport, Typhimurium, and 4,5,12:i:− Isolates in the United States but Differs by Serotype and Geographic Region

Hoelzer

Soyer

Rodriguez‐Rivera

et al. 2010

Appl Environ Microbiol

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“…Outbreak investigations overseas have highlighted that S. Typhimurium MLVA loci appear stable over short periods of time although single-locus variants have been identified [28][29][30][31]. Outbreak investigations overseas have highlighted that S. Typhimurium MLVA loci appear stable over short periods of time although single-locus variants have been identified [28][29][30][31].…”

Section: Discussionmentioning

confidence: 99%

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

2010

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The discriminatory power of multiple-locus variable-number tandem-repeat analysis (MLVA) needs to be evaluated for all Salmonella enterica subspecies enterica serovar Typhimurium (S. Typhimurium) phage types so that the power of this methodology is understood and results can be interpreted correctly during outbreak investigations. We evaluated the ability of MLVA to characterize four definitive phage types (DT) problematic in New Zealand. MLVA discriminated between DT104 isolates although there was very limited variation in the MLVA profiles for isolates with an RDNC phage type (reacts but does not conform to a recognized Typhimurium phage pattern) first observed in New Zealand's Enteric Reference Laboratory in May 2006. Most DT101 isolates had indistinguishable MLVA profiles or profiles that differed at one or two loci. This was also observed in DT160 isolates. MLVA may not identify all common-source outbreaks although it provided valuable data when applied to case isolates from two S. Typhimurium outbreaks.

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“…Strains are assigned a numerical code corresponding to the numbers of tandem repeats in the target loci, and this provides an unambiguous dataset that is easily exchanged between laboratories (Larsson et al 2013). As MLVA has been reported to be highly discriminatory as well as fast and fairly cheap to perform, the method it is now being used by many European laboratories for Salmonella Typhimurium cluster detection and outbreak investigations (Cho et al 2007;Nyg ard et al 2007;Torpdahl et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Multiple-locus variable-number tandem repeat analysis ofSalmonella entericasubsp.entericaserovar Dublin

et al. 2014

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Aims: Salmonella serovar Dublin causes disease in cattle and leads to considerable production losses. In humans, severe invasive disease and high mortality rates are reported. The presently available typing methods provide insufficient discrimination within Salm. Dublin for epidemiological investigations. In this study, we developed a multiple-locus variable-number tandem repeat analysis (MLVA) scheme for high discriminatory typing of Salm. Dublin. Methods and Results: Nine loci of variable number of tandem repeats (VNTRs) were evaluated based on a panel of 40 diverse isolates. The four most discriminative VNTRs were selected for further MLVA analysis. The discriminatory power was evaluated on 272 veterinary and human isolates plus 29 outbreak-related isolates. MLVA divided the 272 isolates into 103 types and successfully identified isolates from an epidemiologically confirmed outbreak. VNTRs exhibited 100% in vitro stability and contained only true repeats. The discriminatory power of the MLVA was compared to pulsed-field gel electrophoresis (PFGE). When analysing a subset of 106 isolates, MLVA obtained 60 types (index of diversity (DI) of 0Á97), while PFGE revealed 10 types (DI of 0Á57). Conclusions:The technique showed a significantly enhanced discriminatory power compared with the current 'gold standard' PFGE. MLVA is a fast and low-cost method. Significance and Impact of the Study: This MLVA method can be recommended to be used in routine subtyping of isolates for outbreak investigations and disease surveillance. The method may provide valuable additional information that can improve the effectiveness of epidemiological investigations of Salm. Dublin infections in patients as well as in the primary production and thereby contribute to the efforts of reducing transmission of infection.

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Outbreak of Salmonella Typhimurium infection traced to imported cured sausage using MLVA-subtyping

Cited by 14 publications

References 0 publications

The Prevalence of Multidrug Resistance Is Higher among Bovine than HumanSalmonellaentericaSerotype Newport, Typhimurium, and 4,5,12:i:− Isolates in the United States but Differs by Serotype and Geographic Region

The Prevalence of Multidrug Resistance Is Higher among Bovine than HumanSalmonellaentericaSerotype Newport, Typhimurium, and 4,5,12:i:− Isolates in the United States but Differs by Serotype and Geographic Region

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

Multiple-locus variable-number tandem repeat analysis ofSalmonella entericasubsp.entericaserovar Dublin

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