Outbreak of Salmonella Bovismorbificans associated with the consumption of uncooked ham products, the Netherlands, 2016 to 2017

Abstract

In January 2017, an increase in reported Salmonella enterica serotype Bovismorbificans cases in the Netherlands was observed since October 2016. We implemented a case–control study to identify the source, including all cases after December 2016. Adjusted odds ratios were calculated using logistic regression analysis. We traced back the distribution chain of suspected food items and sampled them for microbiological analysis. Human and food isolates were sequenced using whole genome sequencing (WGS). From October 2016 to March 2017, 54 S. Bovismorbificans cases were identified. Sequencing indicated that all were infected with identical strains. Twenty-four cases and 37 controls participated in the study. Cases were more likely to have consumed ham products than controls (aOR = 13; 95% CI: 2.0–77) and to have shopped at a supermarket chain (aOR = 7; 95% CI: 1.3–38). Trace-back investigations led to a Belgian meat processor: one retail ham sample originating from this processor tested positive for S. Bovismorbificans and matched the outbreak strain by WGS. All ham products related to the same batch were removed from the market to prevent further cases. This investigation illustrates the importance of laboratory surveillance for all Salmonella serotypes and the usefulness of WGS in an outbreak investigation.

Characterization and whole genome sequencing of closely related multidrug-resistant Salmonella enterica serovar Heidelberg isolates from imported poultry meat in the Netherlands

“…Whole genome sequencing (WGS) provides the means for such extensive surveillance and source tracing within various populations and settings. Nowadays, WGS is increasingly applied as a molecular epidemiological tool for the identification and surveillance of foodborne pathogens and to assist in outbreak investigation [18–20]. WGS provides very high discriminating power to differentiate clinical and epidemiological relevant strains, and allows for detailed molecular characterization.…”

Phenotypic Prediction: Linking in vitro Virulence to the Genomics of 59 Salmonella enterica Strains

“…While some serovars (among more than 2500 in total) dominate the human disease incidence (i.e., Enteritidis and Typhimurium) others rarely cause disease but can be found in animals, food and/or the environment (European Food Safety Authority [EFSA] and European Centre for Disease Prevention and Control [ECDC], 2017). Although outbreaks associated with relatively rare serovars do occur (Brandwagt et al, 2018). Such an epidemiological situation of Salmonella serovars could be the reflection of differences in virulence, in exposure, or both.…”

Characterization of Salmonella Isolates from Wastewater Treatment Plant Influents to Estimate Unreported Cases and Infection Sources of Salmonellosis

“…However, we concurrently isolated this serotype in August 2018 from two isolates of sewage and human origins, and the PFGE pattern of these isolates showed a high similarity (Table 3). Besides, serovar Bovismorbificans, which caused outbreaks from contaminated fresh sprouts and ham products in Germany [34] and the Netherlands [35], respectively, was rarely identified from humans in Japan [29], and only five strains, out of more than 3300 strains, were isolated from humans in the Yamanashi Prefecture between 1985 and 2018 [32,33] (unpublished data). Here, all isolates from two each of sewage and human samples, belonging to this serotype, were concurrently identified in June 2019 (Table 3), and their PFGE patterns were indistinguishable from each other (Figure 1c).…”