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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]

The sensitivity of bacteriological testing of faecal samples from patients with diarrhoea has not been properly determined. The present study analysed the association between the results of stool sample examinations and the number of samples examined per patient and other patient-related factors. Data concerning faecal specimens referred for culture for enteric bacterial pathogens ( Campylobacter, Salmonella, Shigella and Yersinia) to the central microbiological laboratory in Denmark between 1995 and 2003 were analysed. In total, 620 000 samples were sorted into 277 000 sample-series, i.e., samples submitted from the same individual on the same day. Data were analysed by multivariate logistic regression, with the outcome being a positive sample-series, i.e., one or more positive samples per series. Overall, 11.9% of the sample-series were positive. For adults (aged ≥18 years), the OR for a positive diagnosis was 1.20 (95% CI 1.18–1.21) for each additional sample. Positive diagnoses were also more likely during summer, if the patient was male, or if the patient was neither very young nor very old. The added diagnostic effect of additional samples was more pronounced for the group of patients with persistent (>2 weeks) diarrhoea. Overall, the probability of finding common pathogenic bacteria in faecal samples was found to vary according to the number of samples, the season and the patient's age and gender. Analysis of more than one sample improves the sensitivity of faecal culture by at least 20% for each additional sample. [ABSTRACT FROM AUTHOR]

This study describes the prevalence, clinical manifestations and microbiological characteristics of attaching and effacing Escherichia coli isolates, i.e., enteropathogenic E. coli (EPEC) belonging to the classical EPEC serotypes, non-EPEC attaching and effacing E. coli (A/EEC) and verocytotoxin-producing E. coli (VTEC), isolated in a case-control study of Danish children aged <5 years. Among 424 children with diarrhoea and 866 healthy controls, EPEC and VTEC were more prevalent in cases (2.4% and 2.6%, respectively) than in controls (0.7% and 0.7%, respectively). There was a high frequency of A/EEC isolates ( n = 121), but these were equally prevalent in cases (11.3%) and controls (12.5%), and comprised a heterogeneous distribution of O:H serotypes. The intimin ( eae) subtypes in A/EEC isolates showed an even distribution; the eae-γ subtype predominated in classical EPEC cases. The virulence genes encoding the bundle-forming pilus ( bfpA) and enteroaggregative heat-stable enterotoxin ( astA) were rare among all isolates, and seemed to be of limited pathogenic importance in this population. Virulence characterisation of A/EEC isolates did not reveal any significant differences between cases and controls. Colonisation of children with A/EEC was associated with contact with sheep or goats (OR 2.2). The role of A/EEC, not being VTEC or belonging to the classical EPEC serotypes, requires further clarification, but serotyping is useful in discriminating between EPEC and A/EEC strains. [ABSTRACT FROM AUTHOR]

Listeriosis is a rare, but serious, foodborne infection which, in the invasive form, presents as bloodstream (BS) infection, an infection of the central nervous system (CNS), a maternofetal infection or a focal infection. The disease is notifiable in Denmark. This paper reviews the results of the Danish surveillance of invasive listeriosis from 1994 to 2003, excluding maternofetal cases. In total, 299 invasive cases of listeriosis were reported. Two-thirds of the cases were caused by isolates of serogroup 1/2, and one-third by serogroup 4. Most (70%) cases had conditions known to predispose to listeriosis. More patients with BS infection were predisposed because of concurrent underlying illness than were patients with CNS infection. Half of the patients were aged > 70 years, and 21% died of the disease. There was no change in the case fatality rate (CFR) during the 10-year period. The CFR was identical for men and women. BS and CNS infection caused the same incidence of mortality, but no mortality was observed in patients with focal infections at normally sterile body sites. In a multivariate analysis, isolates belonging to serogroup 4 were associated with a higher CFR than were isolates of serogroup 1/2. In patients aged < 70 years, underlying conditions predisposing to disease were related strongly to mortality, which was not the case in patients aged > 70 years. The underlying conditions associated most strongly with mortality in the younger age group were non-haematological malignancies. [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]

Summary: MRSA CC398 is an emerging MRSA strain found in livestock, mainly in pigs. Direct occupational livestock contact is the principal risk factor for human MRSA CC398 infection. Nonetheless, in recent years, an increasing number of MRSA CC398 cases has been observed in persons without known pig contact. Such cases, referred to as MRSA CC398 of unknown origin (MUO CC398), have, like livestock‐onset (LO) MRSA CC398 cases, been found concentrated in rural, livestock‐producing areas. The presence of MUO CC398 cases indicates alternative and unknown MRSA CC398 transmission pathways into the community. We performed a nationwide study in Denmark of the geographic distributions of MRSA cases in general and persons with MUO CC398 or LO MRSA CC398 infections (1 January 2006–11 February 2015), with the Danish population as background population. Place of living of study persons was mapped using the ArcGIS software, and information on pig farms was retrieved from the Central Husbandry Register. The incidence of MUO CC398 infections was clearly higher in rural than in urban areas, and such cases lived on average closer to pig farms than the general population. However, within three pig‐farming‐dense municipalities, patients with MUO CC398 infections did not live closer to pig farms than population controls. This shows that direct environmental spread from neighbouring pig farms of MRSA CC398 is unlikely. Instead, community spread through other means of transmission than direct spread from farms may more likely explain the clustering of MUO CC398 in livestock‐dense areas. [ABSTRACT FROM AUTHOR]

The prevalence of different antimicrobial resistance profiles and variants of the Salmonella genomic island 1 (SGI1) was reported for Salmonella enterica serovar Typhimurium DT104 strains isolated from patients in Denmark. Variation in antimicrobial resistance and corresponding changes of SGI1 were shown among isolates from a foodborne outbreak. [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]

Summary: Campylobacter is the most frequently occurring cause of bacterial gastroenteritis in Europe. Unlike other zoonotic diseases, European‐wide incidences of Campylobacter infections have increased during the past decade, resulting in a significant disease burden. In Denmark, campylobacteriosis is notifiable by laboratory and a unique registration system of electronic transfer and storage of notified Campylobacter cases linked to the national person register of age, gender and geographical location allows collection of comprehensive case data. Using national surveillance data, we describe Campylobacter infections in Denmark from 2000 to 2015, focusing on age‐specific incidences, geography, seasonality and outbreaks. During the observed period, a total of 60,725 Campylobacter infections were registered with a mean annual incidence of 69.3 cases/100,000 population. From 2000 to 2014, the incidence of campylobacteriosis decreased by 20%, followed by an apparent increase of 20% from 2014 to 2015. Approximately one‐third of cases were travel‐related. Incidences were highest in males, young adults aged 20–29 years and children under 5 years of age. Generally, children under 10 years of age living in rural areas were at higher risk of infection. Infection patterns were seasonal with an increase from May to October, peaking in August. Outbreaks were identified each year, including four large waterborne outbreaks which all occurred following heavy rainfall events. For the most part, patterns of Campylobacter infection in Denmark during 2000 to 2015 remained remarkably constant and followed what is known about the disease with respect to demographic, temporal and spatial characteristics. To establish better targeted prevention and control measures, the current knowledge gaps regarding both Campylobacter microbiology (degree of clonal diversity and clustering) and the importance of different risk factors (food versus environment/climate) need to be filled. [ABSTRACT FROM AUTHOR]

Clostridium difficile infection (CDI) is gradually being recognised as a cause of morbidity in the community. We investigated the incidence and clinical characteristics of CDI in a community setting and characterised the C. difficile strains by toxin gene profiling and polymerase chain reaction (PCR) ribotyping. Patients included in the study had attended general practice, primarily because of diarrhoea; CDI patients (259 patients; 121 <2 years of age) had positive cultures for toxigenic C. difficile and non-CDI patients (455 patients) were culture-negative. Outcome variables included the frequency and duration of diarrhoea, vomiting, stomach ache, fever >38 °C, weight loss and sick leave. Data were analysed by logistic regression. CDI patients <2 and ≥2 years of age with C. difficile as the only enteropathogen in the faecal sample reported slimy stools (65 % vs. 62 %), stomach ache (60 % vs. 75 %), weight loss (50 % vs. 76 %) and duration of diarrhoea >15 days (59 % vs. 73 %) as the predominant symptoms. CDI patients ≥2 years old reported duration of diarrhoea >15 days more often compared to non-CDI patients (73 % vs. 27 %, p < 0.0001). The annual incidence of CDI was 518 and 23/100,000 for patients <2 and ≥2 years of age, respectively, and 46/100,000 in the subgroup of patients ≥60 years of age. CDI was characterised by stomach ache and persistent diarrhoea, often leading to weight loss. This emphasises the importance of diagnosing CDI not only in hospitalised patients, but also in individuals ≥2 years of age attending general practice because of gastrointestinal symptoms, especially in the elderly, where the incidence of CDI is high. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to examine incidences of Campylobacter in broilers and humans, and to describe seasonal variation and long-term trends by comparing longitudinal surveillance data in six Northern European countries (Denmark, Finland, Iceland, Norway, Sweden and the Netherlands). Due to high degree of seasonality and autocorrelation, seasonally adjusted (de-seasonalized) and trend adjusted data (de-trended) were used for comparing incidences within and between the six countries. De-seasonalized time series were obtained by fitting the incidence time series to mean monthly temperature and then removing this effect from the data. Long-term trends were fitted to the de-seasonalized time series. The incidence of Campylobacter colonization in broiler flocks and incidence of campylobacteriosis in humans showed a concordant seasonality for all the countries. There was a strong association between the incidence in both broilers and humans in a given month and the mean temperature of the northern hemisphere in the same month, as well as the preceding month, as shown by the cross-correlations and the chosen Generalized Additive Model. Denmark and Sweden showed a steadily decreasing trend for Campylobacter in broilers and human campylobacteriosis in the period 2001–2007. In Iceland, there was a decreasing trend for campylobacteriosis in humans from 1999 to 2007, whilst the broiler trend for Campylobacter was stable from 2001 to 2004, then falling thereafter. In Norway, the human campylobacteriosis trend showed a steady increase throughout the period. On the other hand, the Norwegian broiler trend for Campylobacter showed a decrease from 2001 until 2004, but was thereafter stable. There was no significant decrease or increase in incidence for human campylobacteriosis in the Netherlands, and the trend for Campylobacter in broilers was close to stable. The seasonality seen in broiler and human closely follows the temperature, and was probably caused, at least partly, by temperature related factors. [Copyright &y& Elsevier]

An outbreak of listeriosis in Denmark occurred in May 2009. Multilocus variable number of tandem repeats analysis typing, later confirmed by pulsed-field gel electrophoresis typing, showed that isolates from eight patients had identical patterns and were distinguishable from Listeria monocytogenes isolates from other Danish patients. Seven out of eight patients had received a meal with beef from the same meals-on-wheels delivery catering company 3 weeks prior to onset of disease. Two patients died of their infection. Large-scale delivery of precooked meals to a vulnerable population represents a threat if proper measures against listeriosis are not taken. [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]