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Listeria monocytogenes may contaminate and persist in food production facilities and cause repeated, seemingly sporadic, illnesses over extended periods of time. We report on the investigation of two such concurrent outbreaks. We compared patient isolates and available isolates from foods and food production facilities by use of whole-genome sequencing and subsequent multilocus sequence type and single nucleotide polymorphism analysis. Outbreak cases shared outbreak strains, defined as Listeria monocytogenes isolates belonging to the same sequence type with fewer than five single nucleotide polymorphism differences. We performed routine food consumption interviews of L. monocytogenes patients and compared outbreak cases with sporadic cases. Two outbreaks were defined, each consisting of ten outbreak cases in the period 2013–15. Seven outbreak cases and a fetus in gestational week 38 died. Listeria monocytogenes isolates from cold smoked or gravad fish products or their two respective production environments were repeatedly found to belong to the outbreak strains. Outbreak cases more often than sporadic cases stated that they consumed the relevant fish products, odds ratio 10.7. Routine collection and typing of food isolates was key to solving the outbreaks. Furthermore, these outbreaks illustrate the value of whole-genome sequencing for outbreak definition and investigation. Whole-genome sequencing combined with epidemiological investigations provided the discriminatory power to recognize low-intensity, extended time-period outbreaks and link them to food products from two different contaminated production facilities with sufficient strength for food authorities to intervene on. Cold smoked and gravad fish constitute risk products and may be responsible for more listeriosis cases than previously recognized. [ABSTRACT FROM AUTHOR]

This report concerns a prolonged restaurant-associated outbreak of infection caused by a multidrug-resistant (ASSuT) strain ofSalmonellaTyphimurium, phage-type U302, which took place during July and August 2003 and affected people from Denmark and neighbouring countries who had attended a specific restaurant. The outbreak comprised 67 laboratory-verified cases and ten probable cases; however, the actual number of patients was estimated to be more than 390. The outbreak strain was isolated from a buffet which was probably contaminated by an assistant chef who was found to excrete the epidemic strain. An attack rate of 7.3% was estimated and long incubation periods were observed, including one extreme instance of 27 days. This outbreak underscores the importance of conscientious personal hygiene, including frequent washing of hands, for professionals handling food. [ABSTRACT FROM AUTHOR]

Objectives Shiga toxin-producing Escherichia coli (STEC) causes diarrhoeal disease, bloody diarrhoea, and haemolytic uraemic syndrome. The aim of this study was to describe the incidence of STEC and the clinical features of STEC patients from a well-defined Danish population in which all fecal samples of patients with suspected infective gastroenteritis were analysed for STEC. Methods In this population-based cohort study, all stool samples referred to two clinical microbiology laboratories were screened for STEC by culture and/or PCR. Epidemiological ( n =170) and clinical ( n =209) characteristics were analysed using data from local and national registries. Results Overall, 75,132 samples from 30,073 patients were screened resulting in 217 unique STEC-isolates. The epidemiological analysis showed an incidence of 10.1 cases per 100,000 person-years, which was more than twofold higher than the incidence in the rest of Denmark (3.4 cases per 100,000 person-years, p <0.001). Three groups were associated with a higher incidence: age <5 years ( n =28, p <0.001), age ≥65 years ( n =38, p 0.045), and foreign ethnicity ( n =27, p 0.003). In the clinical analysis, patients with STEC harbouring only the Shiga toxin 1 gene ( stx 1 -only isolates) showed a lower frequency of acute ( n =11, p <0.05) and bloody diarrhoea ( n =5, p <0.05) and a higher frequency of gastrointestinal symptoms for ≥3 months ( n =8, p <0.05) than the other STEC patients. Conclusions We report a more than twofold higher incidence in the project area compared with the rest of Denmark, indicating that patients remain undiagnosed when selective STEC screening is used. We found an association between patients with stx 1 -only isolates and long-term gastrointestinal symptoms. [ABSTRACT FROM AUTHOR]

Objectives Outbreaks of Campylobacter are traditionally considered to be rare; however, rather than being the true nature of the disease, this may reflect our present inability to detect them. The aim of this study was to determine the genetic and epidemiological degree of clustering among Campylobacter jejuni isolates from Danish patients. Methods Whole-genome sequencing (WGS) was applied to 245 C. jejuni isolates from patients with domestically acquired infection over a 9-month period in 2015 and 2016. Results WGS demonstrated that 62 of the 245 isolates (25%) clustered genetically. In total, 21 genetic clusters were identified of which four (18%) consisted of five isolates or more. Seventeen (81%) of the 21 genetic clusters were clustered in space and/or time. Of the 245 isolates, 49 (20%) were part of a temporal and/or geographical cluster. The identified clusters included two outbreaks; one which had not been identified through the existing surveillance system. Conclusions Using WGS, we show that Campylobacter case clustering and even outbreaks appear to occur more often than previously assumed, providing important new insight into the relatively poorly understood epidemiology of the most important cause of bacterial gastroenteritis in the industrialized world. [ABSTRACT FROM AUTHOR]