E de Pinna

Campylobacter and Salmonella in raw red meats in the United Kingdom : Prevalence, characterization and antimicrobial resistance pattern, 2003-2005

The prevalence of Campylobacter and Salmonella was assessed in 3959 raw red meats in the UK during 2003-2005. Meats were more frequently contaminated with Campylobacter (7.2%) than with Salmonella (2.4%). Lamb and other meats (e.g. mutton, rabbit) exhibited the highest contamination from Campylobacter (12.6% and 19.8%, respectively), compared with pork (6.3%) and beef (4.9%). Pork however had the highest contamination from Salmonella (3.9%), followed by lamb (2.0%), other meats (2.0%) and beef (1.3%). Offal samples (36.6%) were more frequently contaminated with Campylobacter or Salmonella than muscle tissue (7.0%). C. jejuni predominated in all meat types. C. coli isolates were more likely to exhibit antimicrobial drug resistance, including quinolones, than C. jejuni. Salmonella typhimurium was the most frequent Salmonella serotype isolated from meats; S. typhimurium DT104/104b isolates exhibited higher rates of multiple drug resistance than other serotypes. The findings reinforce the importance of adequate cooking of meat and good hygiene to avoid cross-contamination.

The microbiological safety of ready-to-eat specialty meats from markets and specialty food shops: a UK wide study with a focus on Salmonella and Listeria monocytogenes.

From 2359 specialty meats (continental sausages, cured/fermented, dried meats) sampled from markets and specialty food shops, 98.9% of samples were of satisfactory or acceptable microbiological quality. However, 16 (0.7%) were unsatisfactory as a result of Escherichia coli, Staphylococcus aureus or Listeria spp. contamination (>or=10(2) CFU/g), and nine (0.4%) were unacceptable due to presence of Salmonella spp. or Listeria monocytogenes (>10(2) CFU/g). Meats with unacceptable levels of L. monocytogenes were within shelf life (range: 8-143 days remaining). Nine different subtypes of L. monocytogenes were detected with sero/AFLP type 1/2c VII predominating (37%), although this subtype was not overrepresented in any particular meat type (P > 0.05). Ninety-six percent of continental sausages and cured/fermented products were stored at <8 degrees C at premises, including seven of the nine unacceptable samples. These nine meats were all pre-packed prior to supply to retail premises (OR = 0.1 P = 0.003) indicating that contamination with bacterial pathogens occurred earlier in the production chain. Most samples (72.7%, 8/11) with unsatisfactory levels of E. coli were sliced on request, suggesting cross-contamination at point of sale. This study highlights the importance of ensuring that products do not become contaminated before final packaging, that storage conditions are controlled, and that durability dates are an accurate indication of the shelf life of the product so as to minimise the potential for L. monocytogenes to be present at levels hazardous to health at the point of sale.

Survey of Salmonella contamination of edible nut kernels on retail sale in the UK

Consumption of nut kernels has shown an upward trend due to peoples increasing tendency to eat healthy snacks. The purpose of this survey was to establish the microbiological safety of retail edible nut kernel samples of different varieties. Overall Salmonella spp. and Escherichia coli were detected from 0.1% and 0.8% of 2886 edible nut kernels, respectively. S. Senftenberg and S. Tennessee were detected from two pre-packed samples of Brazil nuts (0.4%) and S. Anatum from a pre-packed mixed nuts sample (0.9%; mix: almonds, Brazils, cashews, peanuts, walnuts) indicating a risk to health. The levels of Salmonella ranged from <0.01 to 0.23/g. E. coli at unsatisfactory levels (150/g) was present in another pre-packed Brazils nuts sample (0.2%). E. coli was additionally found at lower levels (range: 3.6-43/g) in Brazils (1.9%), macadamia (1.5%), pistachios (1.1%), walnuts (0.7%), peanuts (0.7%), hazels (0.5%), cashews (0.4%), and almonds (0.3%). Levels of E. coli did not correlate with the presence of Salmonella. The batches contaminated with Salmonella were recalled and Food Standards Agency food alerts were issued to advise against the consumption of the affected products. The presence of Salmonella is unacceptable in ready-to-eat foods and follows that the need for applying good agricultural and hygiene practices and effective decontamination procedures during the production of edible kernels cannot be overemphasized.

Assessment of the microbiological safety of salad vegetables and sauces from kebab take-away restaurants in the United Kingdom.

The purpose of this study was to establish the microbiological safety of salad vegetables and sauces served in kebab take-away restaurants. Comparison with published microbiological guidelines revealed that 4.7% of 1213 salad vegetable samples were of unsatisfactory microbiological quality due to Escherichia coli and/or Staphylococcus aureus levels at > or =10(2) cfu g(-1). Another 0.3% of salad samples were of unacceptable quality due to S. aureus at > or =10(4) cfu g(-1) (2 samples) or the presence of Salmonella Kentucky (1 sample). Cucumber was the most contaminated salad vegetable with regards to unsatisfactory levels of E. coli (6.0%) or S. aureus (4.5%). Five percent of 1208 sauce samples were of unsatisfactory microbiological quality due to E. coli, S. aureus at > or =10(2) cfu g(-1) and/or Bacillus cereus and other Bacillus spp. at > or =10(4) cfu g(-1). A further 0.6% of sauce samples were of unacceptable quality due to Bacillus spp. (Bacillus subtilis, Bacillus pumilus, Bacillus licheniformis) at > or =10(5) cfu g(-1) or the presence of Salmonella Agbeni (1 sample). More samples of chili sauce (8.7%) were of unsatisfactory or unacceptable microbiological quality than any other sauce types. The results emphasize the need for good hygiene practices in kebab take-away restaurants handling these types of ready-to-eat products.

An outbreak of Salmonella Typhimurium DT191a associated with reptile feeder mice.

In December 2008 an increase of tetracycline-resistant Salmonella Typhimurium definitive phage-type 191a (DT191a) was identified in England and Wales by the reference laboratory. This was confirmed to have a phage-typing pattern that had not previously been seen. Strong statistical evidence for an association between illness and keeping reptiles was demonstrated by a matched case-case study (mOR 16·82, 95% CI 2·78-∞). Questionnaires revealed an association with frozen reptile feeder mice, and mice representing 80% of the UK supply lines were tested for the presence of Salmonella. DT191a was found in three pools of sampled mice, which were traced back to a single supplier in the USA. Imports from this supplier were halted, and tighter regulations are now in place. A leaflet detailing how to prevent contracting Salmonella from pet reptiles has been published as well as updated advice on the Health Protection Agencys website.

Revival of an old problem: an increase in Salmonella enterica serovar Typhimurium definitive phage type 8 infections in 2010 in England and Northern Ireland linked to duck eggs.

Salmonella enterica serovar Typhimurium definitive phage type (DT) 8 is uncommon in humans in the UK. In July 2010, the Health Protection Agency reported an excess isolation rate of pan-susceptible S. Typhimurium DT8 in England and Northern Ireland. By the end of October, this amounted to 81 laboratory-confirmed human cases for all regions of England and Northern Ireland in 2010, an increase of 26% and 41% on 2009 and 2008, respectively. Descriptive epidemiological investigation found a strong association with infection and consumption of duck eggs. Duck eggs contaminated with S. Typhimurium DT8 were collected from a patients home and also at farms in the duck-egg supply chain. Although duck eggs form a small part of total UK eggs sales, there has been significant growth in sales in recent years. This is the first known outbreak of salmonellosis linked to duck eggs in the UK since 1949 and highlighted the impact of a changing food source and market on the re-emergence of salmonellosis linked to duck eggs. Control measures by the duck-egg industry should be improved along with a continued need to remind the public and commercial caterers of the potential high risks of contracting salmonellosis from duck eggs.

Egg-borne infections of humans with salmonella: not only an S. enteritidis problem

The principal salmonella serovar associated with infections linked to eggs and egg products in the UK, most European countries and North America is Salmonella enteritidis. However, other serovars have also been implicated in a number of egg-associated outbreaks, most notably S. typhimurium exhibiting a range of phage types. The present article reviews human egg-associated salmonellosis associated with non-S. enteritidis serovars, predominantly in the European Union (EU) but also world-wide, using information from published literature and epidemiological databases. There are also brief reviews of S. enteritidis and of mechanisms leading to egg contamination by salmonella. The numbers of egg-associated infections caused by non-S. enteritidis serovars are fairly substantial (for example 22% of outbreaks and 11.5% of more than 20,000 cases in the EU in 2008), and such infections have resulted in hospitalisations and deaths. Furthermore, in parts of the world where S. enteritidis historically has not penetrated laying hen breeding flocks, egg-related salmonellosis is a problem associated specifically with non-S. enteritidis serovars. Control measures to limit the incidence of S. enteritidis and S. typhimurium in poultry flocks are vital. It is therefore important that close surveillance of salmonellosis incidence and serovars in laying flocks is used to establish suitable biosecurity and vaccination programmes throughout EU Member States and elsewhere.

Prospective use of whole genome sequencing (WGS) detected a multi-country outbreak of Salmonella Enteritidis.

Since April 2015, whole genome sequencing (WGS) has been the routine test for Salmonella identification, surveillance and outbreak investigation at the national reference laboratory in England and Wales. In May 2015, an outbreak of Salmonella Enteritidis cases was detected using WGS data and investigated. UK cases were interviewed to obtain a food history and links between suppliers were mapped to produce a food chain network for chicken eggs. The association between the food chain network and the phylogeny was explored using a network comparison approach. Food and environmental samples were taken from premises linked to cases and tested for Salmonella. Within the outbreak single nucleotide polymorphism defined cluster, 136 cases were identified in the UK and 18 in Spain. One isolate from a food containing chicken eggs was within the outbreak cluster. There was a significant association between the chicken egg food chain of UK cases and phylogeny of outbreak isolates. This is the first published Salmonella outbreak to be prospectively detected using WGS. This outbreak in the UK was linked with contemporaneous cases in Spain by WGS. We conclude that UK and Spanish cases were exposed to a common source of Salmonella-contaminated chicken eggs.

Salmonella enterica serovar Agona European outbreak associated with a food company.

We investigated an international outbreak of Salmonella Agona with a distinct PFGE pattern associated with an Irish Food company (company X) producing pre-cooked meat products sold in various food outlet chains in Europe. The outbreak was first detected in Ireland. We undertook national and international case-finding, food traceback and microbiological investigation of human, food and environmental samples. We undertook a matched case-control study on Irish cases. In total, 163 cases in seven European countries were laboratory-confirmed. Consumption of food from food outlet chains supplied by company X was significantly associated with being a confirmed case (mOR 18·3, 95% CI 2·2-149·2) in the case-control study. The outbreak strain was isolated from the companys pre-cooked meat products and production premises. Sufficient evidence was gathered to infer the vehicles of infection and sources of the outbreak and to justify the control measures taken, which were plant closure and food recall.

A Salmonella Typhimurium phage type (PT) U320 outbreak in England, 2008: continuation of a trend involving ready-to-eat products

In March 2008, the Health Protection Agency in England conducted a retrospective case-control study to investigate the cause of 179 cases of the newly recognized, fully antimicrobial-sensitive Salmonella Typhimurium PT U320. Forty-three symptomatic laboratory-confirmed case-patients and 84 asymptomatic location-matched controls were interviewed by telephone about exposures in the 3 days prior to illness or interview. Multivariate logistic analysis indicated consumption of pre-packaged egg sandwiches (odds ratio 3·29, 95% confidence interval 1·19-9·09) was independently associated with illness. Eight of the 15 case-patients who consumed egg sandwiches did so from retail chain A (53·3%) whereas none of the eight controls consumed similar sandwiches (χ2=7·20, P≤0·01). A review of the pre-packaged egg sandwich ingredients suggested this outbreak was probably caused by exposure to an ingredient common to pre-packaged sandwiches and prepared salads but we established a definitive epidemiological link with only the former. Short shelf-life, product diversity and investigation lag hinder epidemiological investigations of such popular products, providing continued challenges for food safety enforcement of freshly prepared produce.