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This article describes the identification and investigation of two extended outbreaks of listeriosis in which crabmeat was identified as the vehicle of infection. Comparing contemporary and retrospective typing data of Listeria monocytogenes isolates from clinical cases and from food and food processing environments allowed the detection of cases going back several years. This information, combined with the analysis of routinely collected enhanced surveillance data, helped to direct the investigation and identify the vehicle of infection. Retrospective whole genome sequencing (WGS) analysis of isolates provided robust microbiological evidence of links between cases, foods, and the environments in which they were produced and demonstrated that for some cases and foods, identified by fluorescent amplified fragment length polymorphism, the molecular typing method in routine use at the time, were not part of the outbreak. WGS analysis also showed that the strains causing illness had persisted in two food production environments for many years and in one producer had evolved into two strains over a period of around 8 years. This article demonstrates the value of reviewing L. monocytogenes typing data from clinical cases together with that from foods as a means of identifying potential vehicles and sources of infection in outbreaks of listeriosis. It illustrates the importance of reviewing retrospective L. monocytogenes typing alongside enhanced surveillance data to characterize extended outbreaks and inform control measures. Also, this article highlights the advantages of WGS analysis for strain discrimination and clarification of evolutionary relationships that refine outbreak investigations and improve our understanding of L. monocytogenes in the food chain. [ABSTRACT FROM AUTHOR]

Outbreaks of foodbome illness caused by Bacillus cereus and Listeria monocytogenes in England associated with meat pie consumption were detected in 2012. To obtain baseline data for pies unrelated to outbreaks, 862 samples of ready-to-eat meat pies were collected at retail or from catering facilities in England in 2013 and examined to enumerate food-poisoning bacteria and indicator organisms using Organization for Standardization (ISO) methods for Listeria spp. including L. monocytogenes (ISO 11290), Clostridium petfringens (ISO 21528), coagulase-positive staphylococci including Staphylococcus aureus (ISO 6888), Bacillus spp. including B. cereus (ISO 1737), Escherichia coli (ISO 16649), Enterobacteriaceae (ISO 21528), and aerobic colony counts (ACCs; ISO 4833). Microbiological quality was satisfactory in 94% of samples, borderline in 5%, and unsatisfactory in 1%. The proportion of pies from markets that were borderline or unsatisfactory significantly increased, and the proportion of borderline or unsatisfactory pies from supermarkets significantly decreased. Among the refrigerated (0 to 15°C) pies, microbiological quality significantly decreased in pies stored at >8°C and further significantly decreased at in pies stored at ambient temperature (>15 to 25°C). Samples collected at 25 to 40°C had the highest proportion of borderline or unsatisfactory results, but results improved in pies stored at >40°C. The most common cause for borderline or unsatisfactory results was elevated ACCs (5% of all samples). Within the individual microbiological parameters, borderline or unsatisfactory results resulted from elevated Enterobacteriaceae or Bacillus levels (10 samples for each), C. petfringens levels (2 samples), and S. aureus or E. coli levels (1 sample each). L. monocytogenes was recovered from one pie at <10 CFU/g. A literature review revealed a range of microbiological hazards responsible for food poisoning and meat pie consumption, and surveillance data from 1992 to 2012 from England indicated that C. petfringens was the most commonly reported cause of outbreaks of foodbome illness. [ABSTRACT FROM AUTHOR]

Fresh fruit has been associated with a number of foodborne outbreaks in recent years. In particular, a large outbreak of listeriosis in the United States in 2011 was associated with consumption of cantaloupe melon, and an outbreak of Salmonella Newport in the United Kingdom and Europe (also in 2011) was linked to watermelon consumption. A study of precut fruit products from catering and retail premises in the United Kingdom was, therefore, carried out to assess their microbiological safety. Between January and March 2012, samples (1,188) of ready-to-eat precut fruit were collected from retail and catering premises in the United Kingdom, and 99% were of satisfactory microbiological quality. However, four samples (0.3%) were of an unsatisfactory quality (one with 800 CFU/g Listeria monocytogenes and three with >100 CFU/g Escherichia coli), and five samples (0.4%) were of a borderline quality owing to the presence of E. coli (two samples with a level of 20 CFU/g), Staphylococcus aureus (two samples with levels of >50 CFU/g), or L. monocytogenes (one sample with a level of 80 CFU/g). L. monocytogenes or other Listeria species were detected in a further 54 samples (4.5%) at levels below the threshold considered to be borderline or unsatisfactory. A significantly larger proportion of samples from one national supermarket chain was contaminated with L. monocytogenes than other supermarkets, and two types were, in this study, unique to this supermarket. This study shows that overall, the microbiological quality of ready-to-eat precut fruit was good. However, the presence of Listeria species in 5% of samples highlights the need for good hygiene during preparation and satisfactory temperature and time control during storage of these food products. [ABSTRACT FROM AUTHOR]

Summary: Background: Norovirus (NoV) is commonly associated with gastrointestinal infection. It is normally transmitted person-to-person or from contaminated surfaces, although food-borne transmission is possible. Methods: We conducted environmental, epidemiological, and microbiological investigations to ascertain the route of transmission of two linked outbreaks of NoV associated with events where food was consumed. Multivariate logistic regression was used to determine food items independently associated with infection. Results: In outbreak A, 19 of the 26 people who completed the food questionnaire fulfilled the case definition. The highest relative risks (RR) were for chicken kebab (RR 3, 95% confidence interval (CI) 0.9–10.4), pork sausages (RR 2.1, 95% CI 0.5–9.1), pasta salad (RR 1.94, 95% CI 0.9–4.1), cheese (RR 1.6, 95% CI 0.9–2.8), and green leaf salad (RR 1.5, 95% CI 0.9–2.4). In outbreak B, 60 of the 106 people surveyed fulfilled the case definition. Green leaf salad (adjusted odds ratio (aOR) 3.2, 95% CI 1.4–9.9) and coleslaw (aOR 8.2, 95% CI 3–22.2) were independently associated with illness in the multivariate logistic regression model. NoV genogroup II genotype 6 (GII-6) was identified in cases of both outbreaks and a food handler who had prepared salads for both events. Conclusion: Because outbreak investigations of small cohorts may not yield epidemiological association to food, most of these outbreaks may be attributed to the person-to-person transmission route. Therefore ascertainment of food-borne NoV infection may be low, underestimating the true prevalence of this route of transmission. [Copyright &y& Elsevier]