Colorectal endoscopic submucosal dissection: a review on patient selection and indications.

Background: The development of 'third-space'-endoscopy has paved the way towards en-bloc resection of early gastrointestinal neoplasia. Endoscopic submucosal dissection (ESD) has improved the endoscopic management of colorectal lesions by facilitating R0-resection, improving histological assessment and preventing recurrence. Methods: The purpose of this review is to provide an evidence-based overview of indications for which ESD should be considered within colorectal endoscopy. Results: The development of ESD has partially bridged the gap between endoscopy and surgery, but depends heavily on adequate pre-resection visual evaluation, ruling out potential deep submucosal invasion. ESD should be considered for large colorectal polyps (≥20mm) and/or lesions diagnosed as harbouring high-grade dysplasia, in-situ carcinoma or superficial submucosal invasion. Not only has it found its way into our guidelines for the treatment of neuroendocrine neoplasms, ESD also seems a promising alternative for the controlled resection of large pedunculated lesions. ESD can also be applied in more challenging situations, such as in pre-treated lesions, post-surgical context and in patients with IBD, although this requires a high level of skill and expertise. Conclusions: In this review we have described the different indications for ESD and attempted to define its place within our current endoscopic armamentarium. For both non-expert and expert endoscopists, knowledge about ESD indications, patient selection and therapeutic alternatives, remains crucial in the care for patients with colorectal neoplasia.

Continuous ADR50 monitoring through automated linkage between endoscopy and pathology: a quality improvement initiative in a Brussels public hospital.

Background and study aim: Adenoma detection rate in patients aged 50 years or older (ADR50) is considered by the European Society of Gastrointestinal Endoscopy (ESGE) a key performance measures for lower gastrointestinal endoscopy. Technical and human resources constrain implementation of recording quality monitoring. The aim was to deploy an infrastructure for continuous monitoring of endoscopy quality indicators. And to evaluate its potential benefit on quality performance. Methods: A company reporting system was adapted by adding a dedicated tab for quality monitoring, including: preparation, progression, number of resected polyps. Automated linkage with the pathology database resulted in continuous monitoring of inter alia: rate of adequate bowel preparation, cecal intubation rate and ADR50. Continuous monitoring was done for all nine endoscopists working at our center, with individual feedback after 4, 9 and 28 months. Results: A total of 1434 colonoscopies were performed during the first 9 months of monitoring, 682 during the first 4 months, 752 during the following 5 months. Five months after feedback a global increase in ADR50 of 4.6% (22.9% to 27.5%) (P<0.05) was observed, compared to the first 4 months. Thus meeting the benchmark (≥25%) recommended by ESGE. A durable effect of monitoring and feedback was observed after 28 months (ADR50: 29.4%). Conclusions: An easy to use infrastructure for registration of quality monitoring in daily endoscopy practice, automatically linking the pathology database, facilitates continuous monitoring of endoscopy quality indicators. A global and durable ADR50 increase was observed after feedback, considered a quality improvement in performance of lower gastrointestinal endoscopy at our center.

Belgian consensus on irritable bowel syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) is characterised by recurrent abdominal pain related to defaecation or associated with altered stool frequency or consistency. Despite its prevalence, major uncertainties in the diagnostic and therapeutic management persist in clinical practice. METHODS: A Delphi consensus was conducted by 20 experts from Belgium, and consisted of literature review and voting process on 78 statements. Grading of recommendations, assessment, development and evaluation criteria were applied to evaluate the quality of evidence. Consensus was defined as > 80 % agreement. RESULTS: Consensus was reached for 50 statements. The Belgian consensus agreed as to the multifactorial aetiology of IBS. According to the consensus abdominal discomfort also represents a cardinal symptom, while bloating and abdominal distension often coexist. IBS needs subtyping based on stool pattern. The importance of a positive diagnosis, relying on history and clinical examination is underlined, while additional testing should remain limited, except when alarm features are present. Explanation of IBS represents a crucial part of patient management. Lifestyle modification, spasmolytics and water-solube fibres are considered first-line agents. The low FODMAP diet, selected probiotics, cognitive behavioural therapy and specific treatments targeting diarrhoea and constipation are considered appropriate. There is a consensus to restrict faecal microbiota transplantation and gluten-free diet, while other treatments are strongly discouraged. CONCLUSIONS: A panel of Belgian gastroenterologists summarised the current evidence on the aetiology, symptoms, diagnosis and treatment of IBS with attention for the specificities of the Belgian healthcare system.

To culture or not to culture: careful assessment of metabarcoding data is necessary when evaluating the microbiota of a modified-atmosphere-packaged vegetarian meat alternative throughout its shelf-life period.

BACKGROUND: As the increased consumption of ready-to-eat meat alternatives is a fairly recent trend, little is known about the composition and dynamics of the microbiota present on such products. Such information is nonetheless valuable in view of spoilage and food safety prevention. Even though refrigeration and modified-atmosphere-packaging (MAP) can extend the shelf-life period, microbial spoilage can still occur in these products. In the present study, the microbiota of a vegetarian alternative to poultry-based charcuterie was investigated during storage, contrasting the use of a culture-dependent method to a culture-independent metagenetic method. RESULTS: The former revealed that lactic acid bacteria (LAB) were the most abundant microbial group, specifically at the end of the shelf-life period, whereby Latilactobacillus sakei was the most abundant species. Metabarcoding analysis, in contrast, revealed that DNA of Xanthomonas was most prominently present, which likely was an artifact due to the presence of xanthan gum as an ingredient, followed by Streptococcus and Weissella. CONCLUSIONS: Taken together, these results indicated that Lb. sakei was likely the most prominent specific spoilage organisms (SSO) and, additionally, that the use of metagenetic analysis needs to be interpreted with care in this specific type of product. In order to improve the performance of metagenetics in food samples with a high DNA matrix but a low bacterial DNA load, selective depletion techniques for matrix DNA could be explored.

The prevalence of disorders of the gut-brain axis in type 2 diabetes mellitus patients with metabolic dysfunction-associated fatty liver disease: an observational study.

BACKGROUND AND STUDY AIM: Disorders of the gut-brain axis (DGBI) and metabolic dysfunction-associated liver disease (MAFLD) are frequently diagnosed and exhibit pathophysiological similarities. This study aimed to estimate the prevalence of DGBI in type 2 diabetes mellitus (T2DM) patients with MAFLD. PATIENTS AND METHODS: In this single center, observational study, in adults with T2DM demographics, diabetes-related parameters and liver tests were recorded. MAFLD was defined by the presence of hepatic steatosis on imaging. Functional dyspepsia (FD) and irritable bowel syndrome (IBS) were diagnosed based on Rome IV criteria. Quality of life (QOL), anxiety levels and depression levels were documented by validated questionnaires. RESULTS: We included 77 patients, 44 with and 33 without steatosis. There were no significant differences in age, body mass index (BMI), waist circumference, HbA1c levels or metformin use between groups. IBS was significantly more prevalent in the liver steatosis group (9/44 vs. 2/33, p = .037), while a similar trend was observed for FD (9/35 vs. 2/31, p = .103). No differences were found in anxiety, depression and overall QOL. However, QOL subscales for health worry, food avoidance and social reaction were significantly higher in the liver steatosis group. CONCLUSIONS: In otherwise comparable T2DM patients, DGBI, and especially IBS, are more prevalent in the presence of MAFLD. This difference could not be attributed to increased levels of anxiety or depression. Future research should target the underlying pathophysiological mechanisms.

Salmonella prevalence and persistence in industrialized poultry slaughterhouses.

Salmonella contamination sources and transmission routes were studied in 5 Belgian poultry slaughterhouses. Samples from the slaughter and cutting line after cleaning and disinfection were collected, as well as neck skin samples and thighs during slaughter of the first flock. In total, 680 swab and water samples were taken from the slaughter line before slaughter. In all slaughterhouses, Salmonella was notwithstanding cleaning and disinfection still isolated from the slaughter line before start of activities. The prevalence of Salmonella in the plucking area was 10.4% (38/365) (hanging area: 5.0%, scalding tank: 5.8%, plucking machine: 17.0%); in the evisceration room, 1.5% (2/138); and in the cutting area, 2.0% (3/149). No Salmonella (0/28) was found in samples from the chilling line. On neck skin samples taken from the various lines, Salmonella prevalence was 16.1% (48/299) after plucking, 16.0% (48/300) after evisceration, 23.3% (70/300) after chilling; on thighs, prevalence was 10.0% (24/240). Nine Salmonella serotypes were identified of which Salmonella Infantis was the most common serovar (53.8%), especially in slaughterhouse A. Two contamination causes were identified; first, although all flocks had an official Salmonella negative status, this was in one case incorrect and led to an enormous contamination of the neck skins of the flock and the slaughterline (i.e., cooling water). Second, molecular typing revealed cross-contamination from flocks slaughtered 1 d before sampling. Salmonella was apparently not always eliminated by the cleaning and disinfection process and able to contaminate the carcasses of the first slaughtered flock. In conclusion, the results of this study provided practical insights for poultry production to further improve their Salmonella control, for example, Salmonella status determination closer to the slaughter date, to adapt cleaning and disinfection protocols especially for critical machinery and better hygienic designed equipment.

The effect of partial depopulation on Campylobacter introduction in broiler houses.

Poultry is seen as the main reservoir for Campylobacter. Control of this zoonotic pathogen in primary production could potentially reduce the colonization in broiler flocks and consequently reduce the number of human infections. In the present study, 20 broiler flocks from 10 farms, were sampled immediately before and 5 to 7 d after partial depopulation (thinning) for the presence of Campylobacter using cecal droppings and overshoes. At the time of thinning, the catching crew, transportation vehicles, forklift, and transport containers were sampled for the presence of Campylobacter. Samples were cultivated; presumed positive isolates were confirmed by PCR. The isolates were molecularly typed by flaA restriction analysis and pulsed field gel electrophoresis. Results show that all flocks were thinned using Campylobacter-contaminated equipment and materials. One-third of the broiler flocks became colonized after thinning. In 67% of the colonization cases, identical strains were found matching those of container systems, transport trucks, and/or forklifts. This identifies thinning as an important risk factor for Campylobacter introduction into broiler houses. Setup and compliance with biosecurity practices during thinning is essential to prevent Campylobacter colonization of broiler flocks.

Evaluation of group vaccination of sows and gilts against Salmonella Typhimurium with an attenuated vaccine in subclinically infected pig herds.

Subclinical Salmonella Typhimurium infections occur frequently in pigs and constitute a major risk for human salmonellosis. With the currently available control measures, Salmonella Typhimurium infections in pigs remain difficult to control. Vaccination has been proposed to be an effective tool to control infections at farm level. In the current study, the effect of group vaccination of sows and gilts against Salmonella Typhimurium is evaluated on Salmonella prevalence in fecal and overshoe samples and ileocecal lymph nodes, and on serology in the sows and their offspring in three subclinically infected pig farms. In each farm, all sows and gilts were vaccinated twice, three weeks apart, with an attenuated histidine-adenine auxotrophic vaccine (Salmoporc®, IDT Biologika). From three months after the group vaccination onwards, all sows were given a booster dose three weeks before every farrowing. The farms were monitored bacteriologically and serologically from 12 months before until 15 months after the group vaccination. After group vaccination, no significant effect was detected in the prevalence of Salmonella Typhimurium in the fecal and overshoe samples collected in the sows (before: 2 %, after: 0 %) and their offspring at 18 weeks (before: 17 %, after: 11 %) and at 26 weeks of age (before: 15 %, after: 7 %), and when combining the results of the offspring at 18 and 26 weeks of age (before: 16 %, after: 9 %). Also, no significant effect was detected in the prevalence of Salmonella Typhimurium positive lymph nodes of sows (before and after: 0 %) and their offspring (before: 4 %, after: 7 %). Regarding serology, the mean S/P-ratios of the sows were significantly higher after the group vaccination, compared to before group vaccination (before: 1.50, after: 2.32, p < 0.001). The mean S/P-ratios of the offspring at slaughter age were significantly lower after the group vaccination, compared to before group vaccination (before: 1.71, after: 1.04, p = 0.001). In conclusion, group vaccination of sows and gilts resulted in a more beneficial serological status of the offspring, but did not significantly decrease Salmonella Typhimurium excretion and lymph node contamination.

Occurrence, distribution and diversity of Listeria monocytogenes contamination on beef and pig carcasses after slaughter.

In this study we investigated the prevalence and location of Listeria monocytogenes and hygiene indicator bacteria on beef and pig carcasses. Carcasses were sampled after slaughter and before cooling at eight and nine sites on the carcass, respectively. For each sample, detection and enumeration of Listeria was performed, as well as the enumeration of Total Aerobic Counts (TAC) and Enterobacteriaceae. The L. monocytogenes isolates were also typed to determine pulsotypes and clonal complexes (CC). L. monocytogenes was detected on 46% [95% CI: 35-56%] of beef and 22% [95% CI: 11-32%] of pig carcasses. Contamination levels at the different carcass sites differed considerably between beef and pigs. Genetic typing of strains suggests that carcass contamination originates from both incoming animals with transmission during slaughter practices as well as persistent (CC9) contamination from the slaughterhouse environment. These findings can be used to understand the complexity of introduction and persistence of this pathogen in slaughter facilities. Accurate correlation of L. monocytogenes presence proved unfeasible with any of the tested hygiene indicator bacteria.

Bacteriological evaluation of vaccination against Salmonella Typhimurium with an attenuated vaccine in subclinically infected pig herds.

Subclinical infections with Salmonella Typhimurium occur frequently in pigs. They constitute a risk for human salmonellosis and are difficult to control with currently available control measures. Vaccination against Salmonella Typhimurium in pigs can be an effective tool to control Salmonella infections at farm level. In the present study, the efficacy of an attenuated Salmonella Typhimurium vaccine (Salmoporc®, IDT Biologika) to control Salmonella infections in pigs was evaluated in three subclinically infected pig herds. The effect on Salmonella excretion and the number of pigs positive for Salmonella Typhimurium field and vaccine strains in ileocecal lymph nodes at slaughter were evaluated using five different vaccination strategies: 1. vaccination of sows, 2. vaccination of sows and piglets, 3. vaccination of sows and fattening pigs, 4. vaccination of piglets, 5. vaccination of fattening pigs, which were all compared to a non-vaccinated control group (experimental group 6). Each vaccination strategy was implemented in each farm, during two consecutive production cycles of the same sows. The prevalence of Salmonella Typhimurium field strain excretion was low; in total, 4% of the fecal and overshoe samples collected in the non-vaccinated control group were Salmonella Typhimurium field strain positive. The excretion of Salmonella Typhimurium field strain did not significantly differ between farms, production cycles and experimental groups. Applying vaccination in either sows and piglets, sows and fattening pigs, or in piglets only, resulted in a significantly reduced number of Salmonella Typhimurium field strain positive lymph nodes of slaughter pigs in the second production cycle, but not in the first production cycle. Vaccination of sows and piglets resulted in the most consistent reduction of Salmonella Typhimurium field strain positive lymph nodes at slaughter. The vaccine strain was detected in the lymph nodes of 13 pigs at slaughter, indicating the possible persistence of the vaccine strain until slaughter. Because of limitations in the study design, and the variability between farms and production cycles, the results of the current observational study should be extrapolated with care. Nevertheless, the results provide evidence that applying vaccination against Salmonella Typhimurium in sows and piglets (preferred), sows and fattening pigs, and piglets only can support the control of Salmonella Typhimurium infections by decreasing the prevalence of Salmonella Typhimurium field strain positive lymph nodes at slaughter.

Effects of attenuated vaccine protocols against Salmonella Typhimurium on Salmonella serology in subclinically infected pig herds.

Vaccination of pigs against Salmonella Typhimurium (S. Typhimurium) can be effective for the control of Salmonella infections at the farm level and reduce the risk of Salmonella contamination in the food chain. However, vaccination may interfere with herd serological status in serology-based Salmonella monitoring programs. The present study investigated the effects of an attenuated S. Typhimurium vaccine (Salmoporc, IDT Biologika) on Salmonella serology in sows, neonatal piglets and slaughter pigs from three subclinically infected herds. Within each herd, five different vaccination protocols were tested as follows: group 1, vaccination of sows; group 2, vaccination of sows and piglets; group 3, vaccination of sows and fattening pigs; group 4, vaccination of piglets; and group 5 vaccination of fattening pigs. Each group was compared to a non-vaccinated control group (group 6). Sera were analyzed by ELISA (HerdChek Swine Salmonella, IDEXX Laboratories) and sample-to-positive (S/P) ratios were calculated. At day 3 after farrowing, but not before vaccination, S/P ratios in vaccinated sows (mean: 2.21) were significantly higher than S/P ratios in non-vaccinated sows (mean: 0.87, P<0.001). S/P ratios in 3-day old piglets from vaccinated sows (mean: 2.46) were significantly higher than S/P ratios in similar piglets from non-vaccinated sows (mean: 0.73, P<0.001). At slaughter, S/P ratios in pigs from groups 2, 3, 4 and 5 were significantly higher than those in the non-vaccinated control group (P<0.001). Therefore, vaccination of piglets and fattening pigs could have implications for current serology-based Salmonella monitoring programs in slaughter pigs.

Quantitative risk model to estimate the level of antimicrobial residues that can be transferred to soil via manure, due to oral treatments of pigs.

Veterinary antimicrobials can spread via manure onto agricultural fields, representing an emission of these products or their active metabolites into the environment. This causes concerns regarding the role of antimicrobial residues in the development, selection and spread of resistance. Aiming to approach this issue quantitatively, first a literature review was performed on the bioavailability and extent of in vivo biotransformation of twelve antimicrobials commonly used in pigs orally, and on the level of their persistence in manure. This information was then used in a model estimating the level of each of these administered antimicrobials that is present in manure at the end of common storage durations in pits and, thus, readily applied onto soil. From the studied antimicrobials, the highest level of residues in stored manure was estimated for doxycycline (55% of the initial amount of doxycycline administered orally to pigs after six months of manure storage), as a combining result of its high use in pigs, low bioavailability and high stability in manure. Other antimicrobials (e.g. amoxicillin) are readily degraded and therefore pose less threat. The results of this study highlight the importance of rational antimicrobial use and of further research on pharmacokinetics of antimicrobials and their degraded products in different environmental compartments, to efficiently control the spread of residues and/or resistance genes from manure to these matrices.

Selection and transfer of an IncI1-tet(A) plasmid of Escherichia coli in an ex vivo model of the porcine caecum at doxycycline concentrations caused by crosscontaminated feed.

AIMS: The aim of this study was to investigate the effect of subtherapeutic intestinal doxycycline (DOX) concentrations (4 and 1 mg l-1 ), caused by cross-contamination of feed, on the enrichment of a DOX-resistant commensal Escherichia coli and its resistance plasmid in an ex vivo model of the porcine caecum. METHODS AND RESULTS: A DOX-resistant, tet(A)-carrying, porcine commensal E. coli strain (EC 682) was cultivated for 6 days in the porcine caecum model under different conditions (0, 1 and 4 mg l-1 DOX). EC 682, other coliforms and anaerobic bacteria were enumerated daily. A selection of isolated DOX-resistant coliforms (n = 454) was characterized by rep-PCR clustering, PCR assays (Inc1 and tet(A)) and micro broth dilution susceptibility tests (Sensititre). Both 1 and 4 mg l-1 DOX-enriched medium had a significantly higher selective effect on EC 682 and other resistant coliforms than medium without DOX. Transconjugants of EC 682 were isolated more frequently in the presence of 1 and 4 mg l-1 DOX compared to medium without DOX. CONCLUSIONS: Subtherapeutic intestinal DOX concentrations have the potential to select for DOX-resistant E. coli, and promote the selection of transconjugants in a porcine caecum model. SIGNIFICANCE AND IMPACT OF THE STUDY: Cross-contamination of feed with antimicrobials such as DOX likely promotes the spread of antimicrobial resistance. Therefore, it is important to develop or fine-tune guidelines for the safe use of antimicrobials in animal feed and its storage.

Reduction of Mycobacterium avium ssp. paratuberculosis in colostrum: Development and validation of 2 methods, one based on curdling and one based on centrifugation.

The aim of this study was to develop and validate 2 protocols (for use on-farm and at a central location) for the reduction of Mycobacterium avium ssp. paratuberculosis (MAP) in colostrum while preserving beneficial immunoglobulins (IgG). The on-farm protocol was based on curdling of the colostrum, where the IgG remain in the whey and the MAP bacteria are trapped in the curd. First, the colostrum was diluted with water (2 volumes colostrum to 1 volume water) and 2% rennet was added. After incubation (1 h at 32°C), the curd was cut and incubated again, after which whey and curd were separated using a cheesecloth. The curd was removed and milk powder was added to the whey. Approximately 1 log reduction in MAP counts was achieved. A reduction in total proteins and IgG was observed due to initial dilution of the colostrum. After curd formation, more than 95% of the immunoglobulins remained in the whey fraction. The semi-industrial protocol was based on centrifugation, which causes MAP to precipitate, while the IgG remain in the supernatant. This protocol was first developed in the laboratory. The colostrum was diluted with skimmed colostrum (2 volumes colostrum to 1 volume skimmed colostrum), then skimmed and centrifuged (at 15,600 × g for 30 min at room temperature). We observed on average 1.5 log reduction in the MAP counts and a limited reduction in proteins and IgG in the supernatant. To obtain a semi-industrial protocol, dairy pilot appliances were evaluated and the following changes were applied to the protocol: after 2:1 dilution as above, the colostrum was skimmed and subsequently clarified, after which the cream was heat treated and added to the supernatant. To investigate the effect of the colostrum treatment on the nutritional value and palatability of the colostrum and the IgG transfer, an animal experiment was conducted with 24 calves. Six received the dam's colostrum, 6 were given untreated purchased colostrum (control), and 2 groups of 6 calves received colostrum treated according to both of the above-mentioned methods. No significant differences were found between the test groups and the dam's colostrum group in terms of animal health, IgG uptake in the blood serum, milk, or forage uptake. Two protocols to reduce MAP in colostrum (for use on-farm or at a central location) were developed. Both methods preserve the vital IgG.

Effect of Organic Acids on Salmonella Shedding and Colonization in Pigs on a Farm with High Salmonella Prevalence.

This study builds on the results of a previous study in which six commercial feed products based on organic acids were evaluated with respect to Salmonella contamination of piglets in an artificially challenged seeder model. In the present study, the efficacy of three of these commercial products was assessed for Salmonella reduction in fattening pigs on one closed farm with a natural high Salmonella prevalence. In each of four fattening compartments, one of the following feed treatments was evaluated during two consecutive fattening rounds: (i) butyric acid (active ingredients at 1.3 kg/ton of feed; supplement A1), (ii) a combination of short-chain organic acids (mixture of free acids and salts) and natural extracts (2.92 kg/ton; supplement A4), (iii) a 1:1 blend of two commercial products consisting of medium-chain fatty acids, lactic acid, and oregano oil (3.71 kg/ton; supplement A5+A6), and (iv) a control feed. On the farm, the Salmonella status of the fattening pigs was evaluated by taking fecal samples twice during the fattening period. At the slaughterhouse, samples were collected from the cecal contents and the ileocecal lymph nodes. Salmonella isolates were serotyped and characterized by pulsed-field gel electrophoresis. This farm had a particularly high number of pigs shedding Salmonella with a wide variety of sero- and pulsotypes. Only the feed blend based on the medium-chain fatty acids was able to significantly reduce Salmonella prevalence both on the farm and at the slaughterhouse. With this combined supplement, the Salmonella reduction in the feces at slaughter age, in cecal contents at slaughter, and the lymph nodes was 50, 36, and 67%, respectively, compared with the control animals. This promising finding calls for further investigation including cost-efficiency of this combined feed product and its effect on the animals.

Phage and MLVA typing of Salmonella enteritidis isolated from layers and humans in Belgium from 2000-2010, a period in which vaccination of laying hens was introduced.

The aim of the study was to characterize isolates of Salmonella enterica serovar Enteritidis (S. Enteritidis) obtained from humans and layer farms in Belgium collected during 2000-2010. Three periods were compared, namely (i) before implementation of vaccination (2000-2004), (ii) during voluntary vaccination (2005-2006) and (iii) during implementation of the national control program (NCP) for Salmonella including mandatory vaccination against S. Enteritidis (2007-2010). The characteristics compared across time periods were distributions of phage type and multiple-locus variable number tandem-repeat assay (MLVA). While PT4 and PT21 were predominantly isolated in Belgium in layers and humans before 2007, a significant reduction of those PTs was observed in both populations in the period 2007-2010. The relative proportion of PT4b, PT21c and PT6c was found to have increased considerably in the layer population since 2007. In the human population, PT8, PT1 and the group of 'other' PTs were more frequently isolated compared to the previous periods. When comparing the proportion of the predominant MLVA types Q2 and U2, no significant difference was found between the layer and human population in the three periods and between periods within each category (layer and human). A significant difference in isolate distribution among MLVA clusters I and II was found between human and layer isolates recovered during Period 3 and in the human population between Period 1 and 3. Results suggest that the association between S. Enteritidis in layers and the occurrence of the pathogen in humans changed since implementation of the NCP in 2007.