Tracing the sources of human salmonellosis: A multi-model comparison of phenotyping and genotyping methods

Mughini‐Gras, Lapo; Smid, Joost; Enserink, Remko; Franz, Eelco; Schouls, Leo M.; Heck, Max; Pelt, Wilfrid van

doi:10.1016/j.meegid.2014.10.003

Cited by 32 publications

(46 citation statements)

References 46 publications

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“…This may differ when modelling attribution at the production or distribution point. The inclusion of food consumption as a parameter was part of the original Hald model [29]; the addition of another parameter, the proportion of food consumed raw or undercooked for each source, was proposed and has been used [33, 57]. Whether to include or not these two parameters in the Dutch or Hald models is not that clear with some studies providing evidence that they are not necessary for the Hald model whereas other studies used one (food consumption) or the two.…”

Section: Discussionmentioning

confidence: 99%

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting

et al. 2017

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Human campylobacteriosis is a common zoonosis with a significant burden in many countries. Its prevention is difficult because humans can be exposed to Campylobacter through various exposures: foodborne, waterborne or by contact with animals. This study aimed at attributing campylobacteriosis to sources at the point of exposure. It combined comparative exposure assessment and microbial subtype comparison with subtypes defined by comparative genomic fingerprinting (CGF). It used isolates from clinical cases and from eight potential exposure sources (chicken, cattle and pig manure, retail chicken, beef, pork and turkey meat, and surface water) collected within a single sentinel site of an integrated surveillance system for enteric pathogens in Canada. Overall, 1518 non-human isolates and 250 isolates from domestically-acquired human cases were subtyped and their subtype profiles analyzed for source attribution using two attribution models modified to include exposure. Exposure values were obtained from a concurrent comparative exposure assessment study undertaken in the same area. Based on CGF profiles, attribution was possible for 198 (79%) human cases. Both models provide comparable figures: chicken meat was the most important source (65–69% of attributable cases) whereas exposure to cattle (manure) ranked second (14–19% of attributable cases), the other sources being minor (including beef meat). In comparison with other attributions conducted at the point of production, the study highlights the fact that Campylobacter transmission from cattle to humans is rarely meat borne, calling for a closer look at local transmission from cattle to prevent campylobacteriosis, in addition to increasing safety along the chicken supply chain.

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Section: Discussionmentioning

confidence: 99%

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting

et al. 2017

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“…We performed source attribution of human salmonellosis cases using the modified Dutch model, which has been presented in detail previously [4,5,8]. Briefly, the model infers probabilistically the most likely sources of human cases by comparing their Salmonella subtype distribution with that of the sources, weighted by the Salmonella prevalence in these sources and the human exposure to them, i.e.…”

Section: Methodsmentioning

confidence: 99%

“…The contribution of the main food-related sources to human salmonellosis is well documented [4-7]. In contrast, the knowledge on the contribution of reptiles is limited [3].…”

Section: Introductionmentioning

confidence: 99%

Increase in reptile-associated human salmonellosis and shift toward adulthood in the age groups at risk, the Netherlands, 1985 to 2014

2016

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While the contribution of the main food-related sources to human salmonellosis is well documented, knowledge on the contribution of reptiles is limited. We quantified and examined trends in reptile-associated salmonellosis in the Netherlands during a 30-year period, from 1985 to 2014. Using source attribution analysis, we estimated that 2% (95% confidence interval: 1.3–2.8) of all sporadic/domestic human salmonellosis cases reported in the Netherlands during the study period (n = 63,718) originated from reptiles. The estimated annual fraction of reptile-associated salmonellosis cases ranged from a minimum of 0.3% (corresponding to 11 cases) in 1988 to a maximum of 9.3% (93 cases) in 2013. There was a significant increasing trend in reptile-associated salmonellosis cases (+ 19% annually) and a shift towards adulthood in the age groups at highest risk, while the proportion of reptile-associated salmonellosis cases among those up to four years-old decreased by 4% annually and the proportion of cases aged 45 to 74 years increased by 20% annually. We hypothesise that these findings may be the effect of the increased number and variety of reptiles that are kept as pets, calling for further attention to the issue of safe reptile–human interaction and for reinforced hygiene recommendations for reptile owners.

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“…Thus far, genotypic data have been applied to attribute cases of campylobacteriosis using population genetic models, e.g., the Asymmetric Island model (AIM), and a recent publication explored the possibility of using the AIM for MLVA‐typed Salmonella data, with a reasonable level of success, The AI model is typically based on the relatedness of multi‐locus sequence types (MLST) from different sources and humans, i.e., how closely are they related and how they may have evolved from each other, and the same concept could, in principle, be applied to MLVA types. It does bring, however, limitations concerning levels of minimum acceptable relatedness when attributing cases to sources, which have been discussed previously .…”

Section: Introductionmentioning

confidence: 99%

Application of Molecular Typing Results in Source Attribution Models: The Case of Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) of Salmonella Isolates Obtained from Integrated Surveillance in Denmark

et al. 2016

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Salmonella is an important cause of bacterial foodborne infections in Denmark. To identify the main animal-food sources of human salmonellosis, risk managers have relied on a routine application of a microbial subtyping-based source attribution model since 1995. In 2013, multiple locus variable number tandem repeat analysis (MLVA) substituted phage typing as the subtyping method for surveillance of S. Enteritidis and S. Typhimurium isolated from animals, food, and humans in Denmark. The purpose of this study was to develop a modeling approach applying a combination of serovars, MLVA types, and antibiotic resistance profiles for the Salmonella source attribution, and assess the utility of the results for the food safety decisionmakers. Full and simplified MLVA schemes from surveillance data were tested, and model fit and consistency of results were assessed using statistical measures. We conclude that loci schemes STTR5/STTR10/STTR3 for S. Typhimurium and SE9/SE5/SE2/SE1/SE3 for S. Enteritidis can be used in microbial subtyping-based source attribution models. Based on the results, we discuss that an adjustment of the discriminatory level of the subtyping method applied often will be required to fit the purpose of the study and the available data. The issues discussed are also considered highly relevant when applying, e.g., extended multi-locus sequence typing or next-generation sequencing techniques.

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Tracing the sources of human salmonellosis: A multi-model comparison of phenotyping and genotyping methods

Cited by 32 publications

References 46 publications

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting

Source attribution of human campylobacteriosis at the point of exposure by combining comparative exposure assessment and subtype comparison based on comparative genomic fingerprinting

Increase in reptile-associated human salmonellosis and shift toward adulthood in the age groups at risk, the Netherlands, 1985 to 2014

Application of Molecular Typing Results in Source Attribution Models: The Case of Multiple Locus Variable Number Tandem Repeat Analysis (MLVA) of Salmonella Isolates Obtained from Integrated Surveillance in Denmark

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