Dissemination of a multidrug resistant CTX-M-65 producer Salmonella enterica serovar Infantis clone between marketed chicken meat and children.

The objective of the present study was to characterize Salmonella enterica serovar Infantis isolated from chicken meat determining their clonal relationships with S. Infantis isolated from children with diarrhea. Fifteen meat-recovered S. Infantis were analyzed. Susceptibility levels to 14 antibacterial agents, the presence of ESBL and that of inducible plasmid-mediated AmpC (i-pAmpC) were determined by phenotypical methods. The presence of ESBL and pAmpC was confirmed by PCR, and detected ESBL-encoding genes were sequenced and their transferability tested by conjugation. The presence of gyrA mutations as well as Class 1 integrons was determined by PCR. Clonal relationships were established by REP-PCR and RAPD. In addition, 25 clinical isolates of S. Infantis were included in clonality studies. All meat-recovered S. Infantis were MDR, showing resistance to ampicillin, nitrofurans and quinolones, while none was resistant to azithromycin, ceftazidime or imipenem. ESBL (blaCTX-M-65) and i-pAmpC (blaDHA) were detected in 2 and 5 isolates respectively (in one case concomitantly), with blaCTX-M-65 being transferable through conjugation. In addition, 1 isolate presented a blaSHV gene. All isolates presented D87Y at GyrA, nalidixic acid active efflux pump and a Class 1 integron of ~1000 bp (aadA1). Clonal analysis showed that all isolates were related. Further they were identical to MDR blaCTX-M-65-producing S. Infantis isolates causing children diarrhea in Lima. The dissemination of MDR blaCTX-M-65-producing S. Infantis between marketed meat and children highlights a public health problem which needs be controlled at livestock level.

Salmonella Serotypes: A Novel Measure of Association with Foodborne Transmission.

Most nontyphoidal Salmonella (NTS) illnesses in the United States are thought to be foodborne. However, transmission routes likely vary among the different serotypes. We developed a relative ranking of NTS serotypes according to the strength of their association with foodborne transmission. We used Laboratory-based Enteric Disease Surveillance data to estimate the proportion of infections for each Salmonella serotype reported from 1998 to 2015 and Foodborne Disease Outbreak Surveillance System data to calculate the proportion of foodborne outbreak-associated Salmonella illnesses caused by each serotype. We calculated the ratios of these proportions to create a foodborne relatedness (FBR) measure for each serotype. Of the top 20 serotypes, Saintpaul (2.14), Heidelberg (1.61), and Berta (1.48) had the highest FBR measures; Mississippi (0.01), Bareilly (0.13), and Paratyphi B variant L(+) tartrate(+) (0.20) had the lowest. The FBRs for the three most prevalent serotypes were 1.22 for Enteritidis, 0.77 for Typhimurium, and 1.16 for Newport. This method provides a quantitative approach to estimating the relative differences in the likelihood that an illness caused by a particular serotype was transmitted by food, which may aid in tailoring strategies to prevent Salmonella illnesses and guide future research into serotype-specific source attribution.

Sources of human infection by Salmonella enterica serotype Javiana: A systematic review.

Non-typhoidal Salmonella (NTS) infection is one of the major causes of diarrheal disease throughout the world. In recent years, an increase in human S. Javiana infection has been reported from the southern part of the United States. However, the sources and routes of transmission of this Salmonella serotype are not well understood. The objective of this study was to perform a systematic review of the literature to identify risk factors for human S. Javiana infection. Using PRISMA guidelines, we conducted a systematic search in Web of Science, PubMed, and the Morbidity and Mortality Weekly Report (MMWR). Searches returned 63 potential articles, of which 12 articles met all eligibility criteria and were included in this review. A review of the literature indicated that both food and non-food (such as animal contact) exposures are responsible for the transmission of S. Javiana infection to humans. Consumption of fresh produce (tomatoes and watermelons), herbs (paprika-spice), dairy products (cheese), drinking contaminated well water and animal contact were associated with human S. Javiana infections. Based on the findings of this study, control of human S. Javiana infection should include three factors, (a) consumption of drinking water after treatment, (b) safe animal contact, and (c) safe food processing and handling procedures. The risk factors of S. Javiana infections identified in the current study provide helpful insight into the major vehicles of transmission of S. Javiana. Eventually, this will help to improve the risk management of this Salmonella serotype to reduce the overall burden of NTS infection in humans.

Occurrence, antimicrobial resistance and whole-genome sequencing analysis of Salmonella isolates from chicken carcasses imported into Iraq from four different countries.

Salmonella is a major cause of human foodborne illnesses worldwide; however, little is known about its occurrence and genomic characteristics in food sources in many developing countries. This study investigates the occurrence, serotypes distribution, antimicrobial resistance, and multilocus sequence types (ST) of Salmonella isolated from 400 imported frozen chicken carcasses sold in the markets of Thi-Qar, south-eastern Iraq. Salmonella was detected in 46 out of 400 tested samples [11.5% (95% confidence interval: 8.5%-15.0%)]. S. Typhimurium was the most abundant (30.4%) among 14 different serotypes recovered from the tested frozen carcasses. Antimicrobial resistance was most frequently detected against tetracycline (84.4%), nalidixic acid (80.4%), streptomycin (69.6%) and trimethoprim/sulfamethoxazole (65.2%). Whole-genome sequencing (WGS) analysis revealed that 18 isolates harbored four ß-lactamase resistance genes, with blaCARB-2 was the most commonly (14/18) detected. It was possible to identify 8 multilocus sequence types from the WGS analysis of 40 out of the 46 Salmonella isolates; with ST-11 (among S. Enteritidis) and ST-19 (among S. Typhimurium) were the most frequently detected. These results add to our understanding of the global epidemiology of Salmonella. Our work stands as one of the first reports on WGS analysis of Salmonella from retail chicken in a Middle-Eastern country. Results from this study could be valuable for guiding an informed import risk analysis aiming at reducing the exposure risk from Salmonella through imported chicken carcasses into Iraq. This work demonstrates the value of WGS as a promising tool for supporting evidence-based food safety hazard characterization.

Campylobacteriosis, Salmonellosis, Yersiniosis, and Listeriosis as Zoonotic Foodborne Diseases: A Review.

Zoonoses are diseases transmitted from animals to humans, posing a great threat to the health and life of people all over the world. According to WHO estimations, 600 million cases of diseases caused by contaminated food were noted in 2010, including almost 350 million caused by pathogenic bacteria. Campylobacter, Salmonella, as well as Yersinia enterocolitica and Listeria monocytogenes may dwell in livestock (poultry, cattle, and swine) but are also found in wild animals, pets, fish, and rodents. Animals, often being asymptomatic carriers of pathogens, excrete them with faeces, thus delivering them to the environment. Therefore, pathogens may invade new individuals, as well as reside on vegetables and fruits. Pathogenic bacteria also penetrate food production areas and may remain there in the form of a biofilm covering the surfaces of machines and equipment. A common occurrence of microbes in food products, as well as their improper or careless processing, leads to common poisonings. Symptoms of foodborne infections may be mild, sometimes flu-like, but they also may be accompanied by severe complications, some even fatal. The aim of the paper is to summarize and provide information on campylobacteriosis, salmonellosis, yersiniosis, and listeriosis and the aetiological factors of those diseases, along with the general characteristics of pathogens, virulence factors, and reservoirs.

Salmonella, Escherichia coli and Enterobacteriaceae in the peanut supply chain: From farm to table.

Due to recent foodborne outbreaks, peanuts have been considered a potential risk for Salmonella transmission. For this reason, the aim of this study was to determine the prevalence and contamination load of Salmonella, Escherichia coli and Enterobacteriaceae throughout the peanut supply chain in Brazil. Samples of peanuts and peanut-containing processed products from post-harvest (n=129), secondary processing (n=185) and retail market (n=100) were analyzed. The results showed high Enterobacteriaceae counts in the post-harvest samples. At the end of the secondary processing, 16% of the samples remained contaminated by this group of microorganisms. Six peanut samples from primary production and one sample of peanut butter were tested positive for E. coli while Salmonella was detected in nine samples (2.2%): six from post-harvest, two from the initial stage of the secondary processing and one from retail. The Salmonella counts ranged between 0.004 and 0.092MPN/g and five serotypes were identified (Muenster, Miami, Javiana, Oranienburg, Glostrup). The results demonstrated a high prevalence of Enterobacteriaceae and low prevalence of E. coli throughout the peanut supply chain. Furthermore, it was verified that peanuts may become contaminated by Salmonella during different stages of the supply chain, especially at post-harvest.

Understanding the Relationships Between Inspection Results and Risk of Foodborne Illness in Restaurants.

Restaurants are important settings for foodborne disease outbreaks and consumers are increasingly using restaurant inspection results to guide decisions about where to eat. Although public posting of inspection results may lead to improved sanitary practices in the restaurant, the relationship between inspection results and risk of foodborne illness appears to be pathogen specific. To further examine the relationship between inspection results and the risk of foodborne disease outbreaks, we evaluated results of routine inspections conducted in multiple restaurants in a chain (Chain A) that was associated with a large Salmonella outbreak in Illinois. Inspection results were collected from 106 Chain A establishments in eight counties. Forty-six outbreak-associated cases were linked to 23 of these Chain A restaurants. There were no significant differences between the outbreak and nonoutbreak restaurants for overall demerit points or for the number of demerit points attributed to hand washing or cross-contamination. Our analyses strongly suggest that the outbreak resulted from consumption of a contaminated fresh produce item without further amplification within individual restaurants. Inspections at these facilities would be unlikely to detect or predict the foodborne illness outbreak because there are no Food Code items in place to stop the introduction of contaminated food from an otherwise approved commercial food source. The results of our study suggest that the agent and food item pairing and route of transmission must be taken into consideration to improve our understanding of the relationship between inspection results and the risk of foodborne illness in restaurants.

Turtles as a Possible Reservoir of Nontyphoidal Salmonella in Shanghai, China.

Terrapins and turtles are known to transmit Salmonella to humans. However, little was known about the occurrence of this pathogen in soft-shelled terrapin that is a popular delicacy in Chinese and other East Asian cuisines. We isolated and characterized 82 (24.4%) isolates of Salmonella from 336 fecal samples of soft-shelled terrapins (51 of 172; 29.7%) and pet turtles (31 of 164; 18.9%) in Shanghai. Salmonella Thompson was the most common serotype (17.1%) among others. Many isolates (84.1%) were resistant to multiple antimicrobials (≥3). Molecular analysis of Salmonella Thompson and Salmonella Typhimurium using pulsed-field gel electrophoresis unveiled a close genetic relationship between several human and terrapin isolates. Our results highlight the risk associated with the handling and consumption of turtles and their role in the spread of Salmonella in the human salmonellosis.

An Approach to Cluster EU Member States into Groups According to Pathways of Salmonella in the Farm-to-Consumption Chain for Pork Products.

The aim of the project as the cluster analysis was to in part to develop a generic structured quantitative microbiological risk assessment (QMRA) model of human salmonellosis due to pork consumption in EU member states (MSs), and the objective of the cluster analysis was to group the EU MSs according to the relative contribution of different pathways of Salmonella in the farm-to-consumption chain of pork products. In the development of the model, by selecting a case study MS from each cluster the model was developed to represent different aspects of pig production, pork production, and consumption of pork products across EU states. The objective of the cluster analysis was to aggregate MSs into groups of countries with similar importance of different pathways of Salmonella in the farm-to-consumption chain using available, and where possible, universal register data related to the pork production and consumption in each country. Based on MS-specific information about distribution of (i) small and large farms, (ii) small and large slaughterhouses, (iii) amount of pork meat consumed, and (iv) amount of sausages consumed we used nonhierarchical and hierarchical cluster analysis to group the MSs. The cluster solutions were validated internally using statistic measures and externally by comparing the clustered MSs with an estimated human incidence of salmonellosis due to pork products in the MSs. Finally, each cluster was characterized qualitatively using the centroids of the clusters.

A Farm Transmission Model for Salmonella in Pigs, Applicable to E.U. Member States.

The burden of Salmonella entering pig slaughterhouses across the European Union is considered a primary food safety concern. To assist E.U. member states with the development of national control plans, we have developed a farm transmission model applicable to all member states. It is an individual-based stochastic susceptible-infected model that takes into account four different sources of infection of pigs (sows, feed, external contaminants such as rodents, and new stock) and various management practices linked to Salmonella transmission/protection (housing, flooring, feed, all-in-all-out production). A novel development within the model is the assessment of dynamic shedding rates. The results of the model, parameterized for two case study member states (one high and one low prevalence) suggest that breeding herd prevalence is a strong indicator of slaughter pig prevalence. Until a member state's' breeding herd prevalence is brought below 10%, the sow will be the dominant source of infection to pigs raised for meat production; below this level of breeding herd prevalence, feed becomes the dominant force of infection.

A Transport and Lairage Model for Salmonella Transmission Between Pigs Applicable to EU Member States.

A model for the transmission of Salmonella between finisher pigs during transport to the abattoir and subsequent lairage has been developed, including novel factors such as environmental contamination and the effect of stress, and is designed to be adaptable for any EU Member State (MS). The model forms part of a generic farm-to-consumption model for Salmonella in pigs, designed to model potentially important risk factors and assess the effectiveness of interventions. In this article, we discuss the parameterization of the model for two case study MSs. For both MSs, the model predicted an increase in the average MS-level prevalence of Salmonella-positive pigs during both transport and lairage, accounting for a large amount of the variation between reported on-farm prevalence and reported lymph-node prevalence at the slaughterhouse. Sensitivity analysis suggested that stress is the most important factor during transport, while a number of factors, including environmental contamination and the dose-response parameters, are important during lairage. There was wide variation in the model-predicted change in prevalence in individual batches; while the majority of batches (80-90%) had no increase, in some batches the increase in prevalence was over 70% and in some cases infection was introduced into previously uninfected batches of pigs. Thus, the model suggests that while the transport and lairage stages of the farm-to-consumption exposure pathway are unlikely to be responsible for a large increase in average prevalence at the MS level, they can have a large effect on prevalence at an individual-batch level.

Multidrug-Resistant Salmonella Heidelberg Associated with Mechanically Separated Chicken at a Correctional Facility.

We describe multidrug-resistant (MDR) Salmonella Heidelberg infections associated with mechanically separated chicken (MSC) served at a county correctional facility. Twenty-three inmates met the case definition. All reported diarrhea, 19 (83%) reported fever, 16 (70%) reported vomiting, 4 (17%) had fever ≥103°F, and 3 (13%) were hospitalized. A case-control study found no single food item significantly associated with illness. Salmonella Heidelberg with an indistinguishable pulsed-field gel electrophoresis pattern was isolated from nine stool specimens; two isolates displayed resistance to a total of five drug classes, including the third-generation cephalosporin, ceftriaxone. MDR Salmonella Heidelberg might have contributed to the severity of illness. Salmonella Heidelberg indistinguishable from the outbreak subtype was isolated from unopened MSC. The environmental health assessment identified cross-contamination through poor food-handling practices as a possible contributing factor. Proper hand-washing techniques and safe food-handling practices were reviewed with the kitchen supervisor.

Salmonella Prevalence and Antimicrobial Susceptibility from the National Animal Health Monitoring System Sheep 2011 Study.

Salmonella is a major cause of foodborne illness and can cause clinical disease in animals. Understanding the on-farm ecology of Salmonella will be helpful in decreasing the risk of foodborne transmission. An objective of this study was to determine the prevalence of Salmonella among fecal samples collected on sheep operations in the United States. Another objective was to compare the use of composite fecal samples with fecal samples collected from individual sheep as a tool for screening sheep flocks for Salmonella. Sheep fecal samples (individual and composite) were collected on operations in 22 states. Salmonella isolates were characterized with regard to species, serotype, and antimicrobial susceptibility profile. Most operations (72.1%) had at least one positive sample and overall 26.9% of samples were positive. The percentage of positive samples varied by animal age class. Composite and individual samples gave similar results. The majority of the isolates (94%) were Salmonella enterica subspecies diarizonae serotype 61:-:1,5,7. Nearly all of the isolates (91.2%) tested for antimicrobial susceptibility were susceptible to all antimicrobials in the panel. The findings suggest that salmonellae typically associated with foodborne disease transmission are infrequently found on sheep operations in the United States.

Event-based surveillance of food- and waterborne diseases in Europe: urgent inquiries (outbreak alerts) during 2008 to 2013.

During 2008 to 2013, 215 outbreak alerts, also known as 'urgent inquiries' (UI), for food- and waterborne diseases were launched in Europe, the majority of them (135; 63%) being related to salmonellosis. For 110 (51%) UI, a potential food vehicle of infection was identified, with vegetables being the most reported category (34;31%). A total of 28% (n = 60) of the outbreaks reported had an international dimension, involving at least two countries (mean: 4; standard deviation: 2; range:2­14). Participating countries posted 2,343 messages(initial posts and replies, excluding updates), with a median of 11 messages per urgent inquiry (range:1­28). Of 60 multicountry UI, 50 involved between two and four countries. The UI allowed early detection of multicountry outbreaks, facilitated the identification of the suspected vehicles and consequently contributed to the timely implementation of control measures. The introduction of an epidemic intelligence information system platform in 2010 has strengthened the role of the Food- and Waterborne Diseases and Zoonoses network in facilitating timely exchange of information between public health authorities of the participating countries.

Human outbreak of Salmonella Typhimurium associated with exposure to locally made chicken jerky pet treats, New Hampshire, 2013.

Pet treats and pet food can be contaminated with Salmonella and other pathogens, though they are infrequently implicated as the source of human outbreaks. In 2013, the New Hampshire Department of Health and Human Services investigated a cluster of Salmonella Typhimurium infections associated with contaminated locally made pet treats. Case-patients were interviewed with standardized questionnaires to assess food, animal, and social histories. Laboratory and environmental investigations were conducted, including testing of clinical specimens, implicated product, and environmental swabs. Between June and October 2013, a total of 43 ill persons were identified. Sixteen patients (37%) were hospitalized. Among 43 case-patients interviewed, the proportion exposed to dogs (95%) and pet treats (69%) in the 7 days prior to illness was statistically higher than among participants in a U.S. population-based telephone survey (61%, p<0.0001 and 16%, p<0.0001, respectively). On further interview, 38 (88%) reported exposure to Brand X Chicken Jerky, the maker of Brand X chicken jerky, or the facility in which it was made. Product testing isolated the outbreak strain from four of four Brand X Chicken Jerky samples, including an unopened package purchased at retail, opened packages collected from patient households, and unpackaged jerky obtained from the jerky maker. A site visit revealed inadequate processing of the chicken jerky, bare-hand contact with the finished product prior to packaging, and use of vacuum-sealed packaging, which may have enabled facultative anaerobic bacteria to proliferate. Seven (78%) of nine environmental swabs taken during the site visit also yielded the outbreak strain. Brand X Chicken Jerky was voluntarily recalled on September 9, 2013. Consumers should be made aware of the potential for locally made products to be exempt from regulation and for animals and animal food to carry pathogens that cause human illness, and be educated to perform hand hygiene after handling pet food or treats.

Attributing foodborne salmonellosis in humans to animal reservoirs in the European Union using a multi-country stochastic model.

A Bayesian modelling approach comparing the occurrence of Salmonella serovars in animals and humans was used to attribute salmonellosis cases to broilers, turkeys, pigs, laying hens, travel and outbreaks in 24 European Union countries. Salmonella data for animals and humans, covering the period from 2007 to 2009, were mainly obtained from studies and reports published by the European Food Safety Authority. Availability of food sources for consumption was derived from trade and production data from the European Statistical Office. Results showed layers as the most important reservoir of human salmonellosis in Europe, with 42·4% (7 903 000 cases, 95% credibility interval 4 181 000-14 510 000) of cases, 95·9% of which was caused by S. Enteritidis. In Finland and Sweden, most cases were travel-related, while in most other countries the main sources were related to the laying hen or pig reservoir, highlighting differences in the epidemiology of Salmonella, surveillance focus and eating habits across the European Union.

Tracing the sources of human salmonellosis: a multi-model comparison of phenotyping and genotyping methods.

Salmonella source attribution is usually performed using frequency-matched models, such as the (modified) Dutch and Hald models, based on phenotyping data, i.e. serotyping, phage typing, and antimicrobial resistance profiling. However, for practical and economic reasons, genotyping methods such as Multi-locus Variable Number of Tandem Repeats Analysis (MLVA) are gradually replacing traditional phenotyping of salmonellas beyond the serovar level. As MLVA-based source attribution of human salmonellosis using frequency-matched models is problematic due to the high variability of the genetic targets investigated, other models need to be explored. Using a comprehensive data set from the Netherlands in 2005-2013, this study aimed at attributing sporadic and domestic cases of Salmonella Typhimurium/4,[5],12:i:- and Salmonella Enteritidis to four putative food-producing animal sources (pigs, cattle, broilers, and layers/eggs) using the modified Dutch and Hald models (based on sero/phage typing data) in comparison with a widely applied population genetics model - the asymmetric island model (AIM) - supplied with MLVA data. This allowed us to compare model outcomes and to corroborate whether MLVA-based Salmonella source attribution using the AIM is able to provide sound, comparable results. All three models provided very similar results, confirming once more that most S. Typhimurium/4,[5],12:i:- and S. Enteritidis cases are attributable to pigs and layers/eggs, respectively. We concluded that MLVA-based source attribution using the AIM is a feasible option, at least for S. Typhimurium/4,[5],12:i:- and S. Enteritidis. Enough information seems to be contained in the MLVA profiles to trace the sources of human salmonellosis even in presence of imperfect temporal overlap between human and source isolates. Besides Salmonella, the AIM might also be applicable to other pathogens that do not always comply to clonal models. This would add further value to current surveillance activities by performing source attribution using genotyping data that are being collected in a standardized fashion internationally.

Salmonella source attribution based on microbial subtyping: does including data on food consumption matter?

Source attribution based on microbial subtyping is being performed in many countries to ascertain the main reservoirs of human salmonellosis and to assess the impact of food safety interventions. To account for differences in exposure, the amount of food available for consumption within a country is often included in Salmonella source attribution models along with the level of contamination. However, not all foods have an equal probability of serving as vehicles for salmonellas, as some foods are more likely to be consumed raw/undercooked than others, posing a relatively higher risk. Using Salmonella data from the Netherlands in 2001-2004, this study aims at elucidating whether and how the incorporation of food consumption data in two source attribution models - the (modified) Dutch and Hald models - affects their attributions. We also propose the incorporation of an additional parameter to weight the amount of food consumed by its likelihood to be consumed raw/undercooked by the population. Incorporating the amount of food consumed caused a drastic change in the ranking of the top reservoirs in the Dutch model, but not in the Hald model, which proved to be insensitive to additional weightings given that its source-dependent factor can account for both food consumption and the ability for foods to serve as vehicles for salmonellas. Compared to attributions without food consumption, the Dutch model including the amount of food consumed showed an increase in the percentage of cases attributable to pigs and a decrease in that of layers/eggs, which became the second reservoir, after pigs. This was not consistent with established knowledge indicating that layers/eggs, rather than pigs, were the main reservoir of human salmonellosis in that period. By incorporating the additional weight reflecting the likelihood for different foods to be consumed raw/undercooked, the attributions of the Dutch model were effectively adjusted, both in terms of ranking and percent contributions of the different reservoirs. We concluded that incorporating food consumption data in the Dutch model can significantly affect the results. Therefore, such data should be either excluded from this model or used together with an additional weight able to adjust the amount of food consumed by its likelihood to be consumed insufficiently cooked. This may help identifying the correct reservoirs, allowing attributions to more closely reflect the real chance for a given food to serve as a vehicle for salmonellas. Conversely, the Hald model works properly irrespective of inclusion of food consumption data.

A community outbreak of Salmonella enterica serotype Typhimurium associated with an asymptomatic food handler in two local restaurants.

Between January and April 2012, the city of Long Beach Department of Health and Human Services investigated an outbreak involving 19 case patients who had tested positive for Salmonella enterica serotype Typhimurium with indistinguishable pulsed-field gel electrophoresis patterns. All cases were residents of or traveled to the city of Long Beach, California, during their incubation period, and the majority of patients reported eating at one of two restaurants in Long Beach. This article describes the outbreak investigation that traced the source to an asymptomatic food handler working at both restaurants and highlights the importance of maintaining a high index of suspicion for food handlers when faced with local outbreaks of diarrheal illness.