Persistence of Mycobacterium paratuberculosis during manufacture and ripening of cheddar cheese

Sarcoidosis, Mycobacterium paratuberculosis and Noncaseating Granulomas: Who Moved My Cheese

Clinical and histological similarities between sarcoidosis and tuberculosis have driven repeated investigations looking for a mycobacterial cause of sarcoidosis. Over 50 years ago, "anonymous mycobacteria" were suggested to have a role in the etiology of sarcoidosis. Both tuberculosis and sarcoidosis have a predilection for lung involvement, though each can be found in any area of the body. A key histopathologic feature of both sarcoidosis and tuberculosis is the granuloma-while the tuberculous caseating granuloma has an area of caseous necrosis with a cheesy consistency; the non-caseating granuloma of sarcoidosis does not have this feature. This article reviews and reiterates the complicity of the infectious agent, Mycobacterium avium subsp. paratuberculosis (MAP) as a cause of sarcoidosis. MAP is involved in a parallel story as the putative cause of Crohn's disease, another disease featuring noncaseating granulomas. MAP is a zoonotic agent infecting ruminant animals and is found in dairy products and in environmental contamination of water and air. Despite increasing evidence tying MAP to several human diseases, there is a continued resistance to embracing its pleiotropic roles. "Who Moved My Cheese" is a simple yet powerful book that explores the ways in which individuals react to change. Extending the metaphor, the "non-cheesy" granuloma of sarcoidosis actually contains the difficult-to-detect "cheese", MAP; MAP did not move, it was there all along.

Isothermal inactivation of Mycobacterium avium subsp. paratuberculosis in curd simulating the stretching phase in pasta-filata cheese process

Raw milk and dairy products are usually considered the major sources of Mycobacterium avium subsp. paratuberculosis (MAP) exposure for humans. During the production process of mozzarella cheese, as well as of other pasta-filata cheeses made with pasteurized or raw milk, curd is heated and stretched by addition of hot or boiling water. This step is the critical point for the inactivation of MAP during the production process, but, to our knowledge, no studies have been published about the thermal death time values of MAP in curd. The aim of this study was to determine the inactivation kinetics of MAP in curd used to produce pasta-filata cheese in six independent experiments. The milk was inoculated with a mix of MAP strains (field and registered strains) and, with the aim to simulate the thermal treatment of the curd during the stretching step, samples of 10 g of contaminated curd were vacuum packed and treated separately at six different temperatures from 60°C to 75°C in a water bath. MAP survival was then evaluated by plate count method and inactivation parameters were estimated for determining the thermal resistance of the pathogen directly in the curd. D-values increased from 0.15 min (D75-value) to 4.22 min (D60-value) and the calculated z-value was 10.2°C. These data aid: (i) to design food thermal process treatments defining acceptance limits of critical control points to ensure safety against MAP; (ii) to predict the time/temperature combinations needed to obtain a certain MAP log reduction during the curd stretching step; (iii) to optimize or validate pasta-filata cheese process.

Putting Crohn's on the MAP: Five Common Questions on the Contribution of Mycobacterium avium subspecies paratuberculosis to the Pathophysiology of Crohn's Disease

For decades, Mycobacterium avium subspecies paratuberculosis (MAP) has been linked to the pathogenesis of Crohn's disease. Despite many investigations and research efforts, there remains no clear unifying explanation of its pathogenicity to humans. Proponents argue Crohn's disease shares many identical features with a granulomatous infection in ruminants termed Johne's disease and similarities with ileo-cecal tuberculosis. Both are caused by species within the Mycobacterium genus. Sceptics assert that since MAP is found in individuals diagnosed with Crohn's disease as well as in healthy population controls, any association with CD is coincidental. This view is supported by the uncertain response of patients to antimicrobial therapy. This report aims to address the controversial aspects of this proposition with information and knowledge gathered from several disciplines, including microbiology and veterinary medicine. The authors hope that this discussion will stimulate further research aimed at confirming or refuting the contribution of MAP to the pathogenesis of Crohn's disease and ultimately lead to advanced targeted clinical therapies.

Mycobacterium avium Subspecies paratuberculosis Infects and Replicates within Human Monocyte-Derived Dendritic Cells

BACKGROUND

Mycobacterium avium subspecies paratuberculosis (MAP), a member of the mycobacteriaceae family, causes Johne's disease in ruminants, which resembles Crohn's disease (CD) in humans. MAP was proposed to be one of the causes of human CD, but the evidence remains elusive. Macrophages were reported to be the only cell where MAP proliferates in ruminants and humans and is likely the major producer of TNFα-associated inflammation. However, whether human dendritic cells (DCs), another major antigen-presenting cell (APC), have the ability to harbor MAP and disseminate infection, remains unknown.

METHODS

Human monocyte-derived dendritic cells (moDCs) were infected with MAP and phagocytosis and intracellular survival were quantified by immunofluorescence (IF) and colony counts, respectively. MoDC cytokine expression was measured via ELISA and their activation state was measured via flow cytometry.

RESULTS

We showed that MAP can infect and replicate in human moDCs as means to evade the immune system for successful infection, through inhibition of the phago-lysosome fusion via the secretion of protein tyrosine phosphatase PtpA. This mechanism initially led to a state of tolerance in moDCs and then subsequently caused a pro-inflammatory response as infection persisted, characterized by the upregulation of IL-6 and TNFα, and downregulation of IL-10. Moreover, we showed that moDCs have the ability to phagocytose up to 18% of MAP, when exposed at a multiplicity of infection of 1:1.

CONCLUSION

Infection and subsequent proliferation of MAP within moDCs could provide a unique means for the dissemination of MAP to lymphoid tissue, while altering immune responses to facilitate the persistence of infection of host tissues in CD.

Targeted Combination Antibiotic Therapy Induces Remission in Treatment-Naïve Crohn's Disease: A Case Series

Prospective trials of anti-mycobacterial antibiotic therapy (AMAT) have proven efficacious in Crohn’s disease (CD) but use as first-line treatment in CD has not been evaluated. This paper reports the outcomes of patients with CD treated with first-line AMAT. This paper consists of a case series of treatment-naïve CD patients who received AMAT as first-line treatment between 2007 and 2014 at a single center. AMAT treatment consisted of rifabutin, clofazimine and clarithromycin, plus either ciprofloxacin, metronidazole or ethambutol. Symptoms, inflammatory blood markers, colonoscopy and histology results, in addition to, the Crohn’s Disease Activity Index (CDAI) were tabulated from patients’ clinical records, and descriptive statistics were conducted. A Wilcoxon signed-rank test assessed the difference in CDAI scores before and while on AMAT. The statistical significance was set at 5%. Clinical remission (CDAI < 150) with rapid improvement in clinical symptoms and inflammatory markers was seen in all eight patients receiving AMAT as sole therapy by 6 weeks. In all eight patients, the median CDAI score decreased significantly, from 289 prior to treatment to 62 at the 12-month follow-up (p < 0.001). Follow-up colonoscopies showed healing of CD ulcers, no visible mucosal inflammation, restoration of normal vascular patterns and complete mucosal healing on histology samples. AMAT as first-line therapy demonstrated a rapid improvement of Crohn’s disease (not previously seen when used as second-line therapy).

The Impact of the Antimicrobial Compounds Produced by Lactic Acid Bacteria on the Growth Performance of Mycobacterium avium subsp. paratuberculosis

Cell-free supernatants (CFSs) extracted from various lactic acid bacteria (LAB) cultures were applied to Mycobacterium avium subsp. paratuberculosis (MAP) cells to determine their effect on MAP viability. In addition, 5% lactic acid (LA; pH 3) and commercially synthetized nisin bacteriocin were also tested. This procedure was chosen in order to mimic the influence of LAB compounds during the production and storage of fermented milk products, which can be contaminated by MAP. Its presence in milk and milk products is of public concern due to the possible ingestion of MAP by consumers and the discussed role of MAP in Crohn’s disease. Propidium monoazide real-time PCR (PMA qPCR) was used for viability determination. Although all CFS showed significant effects on MAP viability, two distinct groups of CFS – effective and less effective – could be distinguished. The effective CFSs were extracted from various lactobacilli cultures, their pH values were mostly lower than 4.5, and their application resulted in >2 log₁₀ reductions in MAP viability. The group of less effective CFS were filtered from Lactococcus and enterococci cultures, their pH values were higher than 4.5, and their effect on MAP viability was <2 log₁₀. LA elicited a reduction in MAP viability that was similar to that of the group of less effective CFS. Almost no effect was found when using commercially synthetized nisin at concentrations of 0.1–1000 μg/ml. A combination of the influence of the type of bacteriocin, the length of its action, bacteriocin production strain, and pH are all probably required for a successful reduction in MAP viability. However, certain bacteriocins and their respective LAB strains (Lactobacillus sp.) appear to play a greater role in reducing the viability of MAP than pH.

Mycobacterium avium subspecies paratuberculosis - an important food borne pathogen of high public health significance with special reference to India: an update

This review underlines the public health significance of 'Indian Bison Type' of Mycobacterium avium subspecies paratuberculosis (MAP) and also its potential as 'zoonotic infection'. In the absence of control programs, bio-load of MAP is increasing and if we take total population of animals (500 million plus) and human beings (1.23 billion plus) into account, the number of infected animals and human beings will run into millions in India. Our research on screening of over 26,000 domestic livestock for MAP infection using 4 different diagnostic tests (microscopy, culture, ELISA and PCR), during last 31 years has shown that the average bio-load of MAP in the livestock population of India is very high (cattle 43%, buffaloes 36%, goats 23% and sheep 41%). 'Mass screening' of 28,291 human samples between 2008-2016 revealed also high bio-load of MAP. It has been proved that MAP is not in-activated during pasteurization and therefore live bacilli are continuously reaching human population by consumption of even pasteurized milk and other milk products. Live bacilli have also been recovered from meat products and the environment thus illustrating the potential of MAP as pathogen of public health concern. However, at present, there is inadequate scientific evidence to confirm a conclusive link between MAP infection and Johne's disease in ruminants and some cases of Crohn's disease in human beings.

Detection of mycobacterium avium subsp. paratuberculosis in cheeses from small ruminants in Tuscany

Paratuberculosis is an infectious disease which affects mainly domestic and wild ruminants caused by Mycobacterium avium subsp. paratuberculosis (Map). Map has been associated with human diseases like Crohn disease, type-1 diabetes, sarcoidosis, multiple sclerosis and Hashimoto's thyroiditis. The aim of this study was to determine the level of Map positivity of cheeses produced in Tuscany (Italy) as an indication of human exposure to the specific pathogen. Sampling was focused on artisanal cheeses produced without commercial starter culture from raw sheep or goat milk, on small-scale farms. Samples were tested by quantitative PCR (qPCR) and culture. Map DNA was detected in 4/7 (57.14%) goat, and in 14/25 (56%) sheep cheeses by qPCR, whereas cultivation produced a positive result in only one case. This corresponded to a goat cheese that had also reacted positively by qPCR and yielded a viable Type S (sheep) strain of Map. The Map load of the tested samples based on qPCR ranged from 6×10 to 1.8×10(4)Map cells/g of cheese. The results indicate on average 56.57% and 66.6% positivity of cheese samples and farms, respectively. Hence, the type of cheeses that were analyzed within the context of this study seem to constitute a considerable source of human exposure to Map; although the question remains of whether the Map cells were present in a viable form, since positive results were almost exclusively recorded by qPCR.

Detection of Mycobacterium avium subsp. paratuberculosis in a sheep flock in Tuscany

Paratuberculosis is an infectious disease which affects ruminants. In this work, a sheep flock in Garfagnana district (Tuscany, Italy) was examined by agar gel immune-diffusion (AGID) tests, culture, and PCR from feces, milk, tissue samples, and cheeses. At the first AGID test, 7/280 (2.5 %) animals were positive. From these animals, feces and milk samples were collected: 4/7 feces (57.14 %) and 2/7 milk samples (28.57 %) were positive to culture and 7/7 (100 %) feces samples and 1/7 milk samples (14.28 %) were positive to PCR; 2/4 (50 %) cheeses ripened for 14 days and 1/3 (33.33 %) cheese ripened for 20 days were positive to PCR, from which no viable microorganisms were isolated. Then, the AGID-positive animals were slaughtered and tissue samples were taken from one sheep with PCR-positive feces and milk: the liver, intestine, mesenteric lymph nodes, but not the spleen and mammary lymph nodes were positive to culture; all these samples were instead PCR-positive. After 1 year, a second AGID survey was performed on the remaining animals: 6/244 (2.45 %) subjects were positive to this test. Data obtained revealed the presence of paratuberculosis in a sheep population in Garfagnana.

What Role Does Mycobacterium avium subsp. paratuberculosis Play in Crohn's Disease?

Crohn's disease (CD) is a chronic, debilitating inflammatory bowel disease with no etiological agent yet identified. Studies have demonstrated that the bacterium Mycobacterium avium subsp. paratuberculosis (MAP) is present in a high percentage of CD patients. Although MAP has been isolated from human specimens, current techniques fail to show the presence of MAP in 100 % of tissues or biopsies obtained from CD patient lesions, and thus MAP cannot meet Koch's postulate as the etiological agent of CD. In this report, the effect of genetic and immune factors as well as the presence of MAP as a potential environmental factor is analyzed.

Mycobacterium paratuberculosis as a cause of Crohn's disease

Crohn's disease is a chronic inflammatory bowel disease of unknown cause, affecting approximately 1.4 million North American people. Due to the similarities between Crohn's disease and Johne's disease, a chronic enteritis in ruminant animals caused by Mycobacterium avium paratuberculosis (MAP) infection, MAP has long been considered to be a potential cause of Crohn's disease. MAP is an obligate intracellular pathogen that cannot replicate outside of animal hosts. MAP is widespread in dairy cattle and because of environmental contamination and resistance to pasteurization and chlorination, humans are frequently exposed through contamination of food and water. MAP can be cultured from the peripheral mononuclear cells from 50-100% of patients with Crohn's disease, and less frequently from healthy individuals. Association does not prove causation. We discuss the current data regarding MAP as a potential cause of Crohn's disease and outline what data will be required to firmly prove or disprove the hypothesis.

Short communication: Viable Mycobacterium avium subspecies paratuberculosis in retail artisanal Coalho cheese from Northeastern Brazil

Mycobacterium avium ssp. paratuberculosis (MAP) is the etiologic agent of paratuberculosis and it potentially plays a role in Crohn's disease. In humans, the main route of transmission of MAP might be the intake of contaminated milk and dairy products. Considering that MAP has already been detected in many types of cheese in different counties, and that Coalho cheese is an important dairy product in northeastern Brazil, the aim of this study was to report the first detection of MAP in retail Coalho cheese in Brazil by PCR and culture. Of 30 retail Coalho cheese samples, 3 (10%) amplified fragments of a similar size to that expected (626 bp) were obtained and viable MAP was recovered by culture from 1 (3.3%) sample. The DNA from the positive culture sample was sequenced and showed 99% identity with the insertion sequence IS900 deposited in GenBank. It was possible to identify the presence of MAP-specific DNA in the analyzed samples for the first time in Brazil, and to recover viable cells from retail Coalho cheese.

Effect of inflammatory bowel disease therapies on immunogenicity of Mycobacterium paratuberculosis proteins

BACKGROUND AND AIMS

The link between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) is supported by several studies that have reported the detection and isolation of MAP from human tissues, but causation has not yet been proven. Preliminary studies have shown higher levels of antibodies in sera from CD patients against secreted protein from MAP within human macrophages when compared to healthy controls. The immunogenicity of this protein in CD patients under different treatment regimes was evaluated.

MATERIALS AND METHODS

Sera of 110 CD patients, 82 ulcerative colitis (UC), and 150 healthy controls were collected and the presence of antibodies against the mycobacterial protein tyrosine phosphatase PtpA was assayed using ELISA.

RESULTS

A statistically significant difference in the level of antibodies against PtpA was measured in untreated CD patients versus healthy controls, but variation in the antibody levels was observed when patients were subjected to different treatment regimens. UC patients showed no differences in the levels of antibodies against PtpA when compared to healthy controls.

CONCLUSIONS

CD patients under different drug treatments show a clear difference in the levels of antibodies against a protein secreted by MAP, suggesting that if MAP is active in the progress of CD, some treatments can be detrimental to its survival.

Growth of Mycobacterium avium subsp. paratuberculosis, Escherichia coli, and Salmonella Enteritidis during Preparation and Storage of Yogurt

The purpose of this study was to determine the viability of Mycobacterium avium subsp. paratuberculosis (MAP), Escherichia coli (E. coli), and Salmonella Enteritidis (S. Enteritidis) during preparation and refrigerated storage of yogurt. Three yogurts were prepared using pasteurized commercial milk. Each yogurt was artificially contaminated with (1) MAP, (2) E. coli + S. Enteritidis, and (3) MAP + E. coli + S. Enteritidis. Samples were taken during and after the fermentation process until day 20 after inoculation. MAP was not detected during their preparation and short-term storage but was recuperated after starting at 180 min after inoculation storage. Live bacterial counts of E. coli, and S. Enteritidis increased during the first 24 hours, followed by a slight decrease towards the end of the study. In this study it was shown how MAP, E. coli, and S. Enteritidis resisted the acidic conditions generated during the preparation of yogurt and low storage temperatures. This work contributes to current knowledge regarding survival of MAP, E. coli, and S. Enteritidis during preparation and refrigerated storage of yogurt and emphasizes the need to improve hygiene measures to ensure the absence of these pathogenic microorganisms in dairy products.

Gene expression profiling of Mycobacterium avium subsp. paratuberculosis in simulated multi-stress conditions and within THP-1 cells reveals a new kind of interactive intramacrophage behaviour

BACKGROUND

Recent studies have identified in Mycobacterium avium subsp. paratuberculosis (MAP), already known as a pathogen in ruminants, a potential zoonotic agent of some autoimmune diseases in humans. Therefore, considering the possible risk for public health, it is necessary a thorough understanding of MAP's gene expression during infection of human host as well as the identification of its immunogenic and/or virulence factors for the development of appropriate diagnostic and therapeutic tools.

RESULTS

In order to characterize MAP's transcriptome during macrophage infection, we analyzed for the first time the whole gene expression of a human derived strain of MAP in simulated intraphagosomal conditions and after intracellular infection of the human macrophage cell line THP-1 by using the DNA-microarray technology. Results showed that MAP shifts its transcriptome to an adaptive metabolism for an anoxic environment and nutrient starvation. It up-regulates several response factors to oxidative stress or intracellular conditions and allows, in terms of transcription, a passive surface peptidoglycan spoliation within the macrophage along with an intensification of the anabolic activity for lipidic membrane structures.

CONCLUSIONS

These results indicate a possible interactive system between MAP and its host cell based on the internal mimicry unlike other intracellular pathogens, bringing new hypothesis in the virulence and pathogenicity of MAP and its importance in human health.

Mycobacterium avium subsp. paratuberculosis survival during fermentation of soured milk products detected by culture and quantitative real time PCR methods

Mycobacterium avium paratuberculosis (MAP), etiological agent of paratuberculosis in ruminants, is able to survive extreme conditions like very low pH (stomach), high temperature (pasteurization) or low temperature (refrigerated storage). Cheese, infant powder milk, cream and other milk and dairy products might thus be considered as possible sources of MAP for humans. The aim of this study was to investigate the survival of two MAP field isolates during fermentation of three different types of soured milk products (SMP; yogurt, acidophilus milk and kefir) under laboratory conditions. Pasteurized MAP-free milk was artificially contaminated with 10(6)MAPcells/mL and survival and absolute numbers of MAP were monitored during fermentation (4 or 16 h) and after six weeks of storage at 4°C by culture and quantitative real time PCR (qPCR). Viability of MAP was determined by culture using Herrold's egg yolk medium and Middlebrook 7H10 with antibiotics, supplemented with Mycobactin J and incubated at 37°C for up to 12 weeks. The absolute numbers of MAP were quantified by previously published qPCR assays targeting F57 and IS900 loci in MAP genome. We herein confirm that MAP can survive pH reduction, however, longer exposure to pH below 4 in SMP seems to be critical because it inhibits growth. Therefore, it is suggested that probiotic cultures that can decrease pH below 4 during fermentation could provide better inactivation of MAP in SMP.

Identification and characterization of a spore-like morphotype in chronically starved Mycobacterium avium subsp. paratuberculosis cultures

Mycobacteria are able to enter into a state of non-replication or dormancy, which may result in their chronic persistence in soil, aquatic environments, and permissive hosts. Stresses such as nutrient deprivation and hypoxia provide environmental cues to enter a persistent state; however, a clear definition of the mechanism that mycobacteria employ to achieve this remains elusive. While the concept of sporulation in mycobacteria is not novel, it continues to spark controversy and challenges our perceptions of a non-replication. We investigated the potential role of sporulation in one-year old broth cultures of Mycobacterium subsp. paratuberculosis (MAP).

We show that dormant cultures of MAP contain a mix of vegetative cells and a previously unknown morphotype resembling a spore. These spore-like structures can be enriched for using sporulating media. Furthermore, purified MAP spore forms survive exposure to heat, lysozyme and proteinase K. Heat-treated spores are positive for MAP 16SrRNA and IS900. MAP spores display enhanced infectivity as well as maintain acid-fast characteristics upon germination in a well-established bovine macrophage model. This is the first study to demonstrate a new MAP morphotype possessing spore-like qualities. Data suggest that sporulation may be a viable mechanism by which MAP accomplishes persistence in the host and/or environment. Thus, our current understanding of mycobacterial persistence, pathogenesis, epidemiology and rational drug and vaccine design may need to be reevaluated.

Antibodies recognizing Mycobacterium avium paratuberculosis epitopes cross-react with the beta-cell antigen ZnT8 in Sardinian type 1 diabetic patients

The environmental factors at play in the pathogenesis of type 1 diabetes (T1D) remain enigmatic. Mycobacterium avium subspecies paratuberculosis (MAP) is transmitted from dairy herds to humans through food contamination. MAP causes an asymptomatic infection that is highly prevalent in Sardinian T1D patients compared with type 2 diabetes (T2D) and healthy controls. Moreover, MAP elicits humoral responses against several mycobacterial proteins. We asked whether antibodies (Abs) against one of these proteins, namely MAP3865c, which displays a sequence homology with the β-cell protein zinc transporter 8 (ZnT8) could be cross-reactive with ZnT8 epitopes. To this end, Ab responses against MAP3865c were analyzed in Sardinian T1D, T2D and healthy subjects using an enzymatic immunoassay. Abs against MAP3865c recognized two immunodominant transmembrane epitopes in 52-65% of T1D patients, but only in 5-7% of T2D and 3-5% of healthy controls. There was a linear correlation between titers of anti-MAP3865c and anti-ZnT8 Abs targeting these two homologous epitopes, and pre-incubation of sera with ZnT8 epitope peptides blocked binding to the corresponding MAP3865c peptides. These results demonstrate that Abs recognizing MAP3865c epitopes cross-react with ZnT8, possibly underlying a molecular mimicry mechanism, which may precipitate T1D in MAP-infected individuals.

Mycobacterium avium subsp. paratuberculosis in dairy products, meat, and drinking water

Mycobacterium avium subsp. paratuberculosis (Map) is the cause of Johne's disease, a chronic infection of the gut, in ruminant animals that provide milk and/or meat for human consumption. Map also may be involved in Crohn's disease and type 1 diabetes in humans. Although the role of Map in human diseases has not been established, minimizing the exposure of humans to the organism is considered desirable as a precautionary measure. Infected animals can shed Map in feces and milk, and the organism can become disseminated in tissues remote from the gut and its associated lymph nodes. The presence of at least some Map in raw milk and meat and in natural waters is likely, but the numbers of Map in those foods and waters should be reduced through cooking or purification. The available information relating to Map in milk and dairy products, meats, and drinking water is reviewed here for assessment of the risks of exposure to Map from consumption of such foods and water.

Immunogenicity of Mycobacterium avium subsp. paratuberculosis proteins in Crohn's disease patients

The association between Mycobacterium avium subsp. paratuberculosis (MAP) and Crohn's disease (CD) is supported by several studies reporting the detection or isolation of MAP from human tissues, but a direct association is still debatable.

OBJECTIVE

To evaluate the survival of MAP in human intestinal cells and to measure the presence of antibodies against two mycobacterial proteins necessary for the survival of the bacterium in the sera of CD patients.

MATERIAL AND METHODS

Human-derived intestinal cells were infected with three isolates of MAP and the survival of the microorganism was determined. The presence of antibodies against protein tyrosine phosphatase A (PtpA) and protein kinase G (two proteins secreted within the host in the early stages of the invasion) in the sera of CD patients was evaluated. Sera of 20 CD patients and 20 controls were collected and the presence of the antibodies was assayed using enzyme-linked immunosorbent assay (ELISA). Secretion of the PtpA in vivo was visualized by immunostaining.

RESULTS

MAP survived in intestinal cells, and immunostaining of PtpA showed that the protein was secreted within these cells. Wilcoxon rank sum test revealed that CD patient sera had significantly higher titer of antibodies specific for both of these antigens compared to controls. ELISA results for either protein were not statistically different between men and women.

CONCLUSIONS

The presence of specific antibodies against mycobacterial proteins essential for establishing an infection in the host suggests that MAP can potentially be active in CD patients, and a serological test can be developed for early detection of MAP in CD patients.

Detection of Mycobacterium avium ssp. paratuberculosis in cheese, milk powder and milk using IS900 and f57-based qPCR assays

AIMS

To develop a quantitative PCR assay for sensitive and specific detection of Mycobacterium avium ssp. paratuberculosis (Map) in a range of dairy products.

METHODS AND RESULTS

TaqMan(®) assays were designed to target the IS900 and f57 genetic elements of Map. Both real-time PCR assays were integrated with the Adiapure(®) Map DNA extraction kit and assessed separately for the detection/quantification of Map in spiked milk, Cheddar cheese and milk powder. Assays were validated against Cheddar cheese samples containing known concentrations of Map. The IS900 qPCR assay was significantly more sensitive than the assay based on the f57 primer/probe. At a threshold cycle value of 38, limits of detection (LOD) for the IS900 qPCR assay were 0·6 CFU ml(-1), 2·8 CFU g(-1) and 30 CFU g(-1) for artificially contaminated pasteurized milk, whole milk powder and Cheddar cheese, respectively. The respective LOD's for the f57 assay were 6·2 CFU ml(-1), 26·7 CFU g(-1) and 316 CFU g(-1).

CONCLUSION

The integrated Adiapure(®) extraction - IS900 real time assay described is a sensitive, quantitative method for the detection of Map in dairy products. This is the first study to consider qPCR as a quantitative estimation of Map-DNA in cheese and whole milk powder.

SIGNIFICANCE AND IMPACT OF THE STUDY

The assay developed allows sensitive detection and quantification of Map DNA in a range of dairy products which is valuable for the screening and surveillance of this potential zoonotic organism.

Assessment of food as a source of exposure to Mycobacterium avium subspecies paratuberculosis (MAP)

The National Advisory Committee on Microbiological Criteria for Foods assessed the importance of food as a source of exposure to Mycobacterium avium subspecies paratuberculosis (MAP). MAP is the causative agent of Johne's disease, which affects primarily the small intestine of all ruminants. The significance of MAP as a human pathogen is unknown and is being investigated by several research groups. This document also reviews the efficacy of current detection methods, processing interventions, and MAP inactivation. Research needs related to MAP are provided. The Committee reached the following conclusions: current methods for detection of MAP have significant limitations, and a standard method for the detection of viable MAP cells is needed. Aside from MAP-infected domestic ruminant animals, the organism is found infrequently. If MAP in cattle is controlled, the source of MAP in other animals, food, and water may largely be eliminated. Milk, particularly raw milk, may be a likely food source for human exposure to MAP. Given the prevalence of MAP in U.S. cattle herds, ground beef may be a potential source of MAP. Although humans may be exposed to MAP through a variety of routes, including food and the environment, the frequency and amount of exposure will require additional research.

Optimization of a phage amplification assay to permit accurate enumeration of viable Mycobacterium avium subsp. paratuberculosis cells

A commercially available phage amplification assay, FASTPlaqueTB (Biotec Laboratories, Ipswich, United Kingdom), when used according to the manufacturer's instructions, does not permit accurate enumeration of Mycobacterium avium subsp. paratuberculosis. The aim of this study was to optimize the phage amplification assay conditions to permit accurate quantification of viable M. avium subsp. paratuberculosis cells. The burst time for M. avium subsp. paratuberculosis was initially determined to inform decisions about optimal incubation time before plating, and then other test parameters were altered to evaluate how the correlation between plaque and colony counts was affected. The D29 mycobacteriophage replicates more slowly in M. avium subsp. paratuberculosis than in Mycobacterium smegmatis (used to optimize the commercial test originally), and the mean burst time for four M. avium subsp. paratuberulosis strains was 210 +/- 36.8 min at 37 degrees C compared to 63 +/- 17.5 min for M. smegmatis mc(2) 155. To achieve 100% correlation between plaque and colony counts, the optimized phage assay includes the following: (i) resuspension of the samples to be tested in Middlebrook 7H9 broth containing 10% oleic acid-albumin-dextrose-catalase and 2 mM calcium chloride, followed by overnight incubation at 37 degrees C before performance of the phage assay; (ii) a 2-h incubation of the sample with D29 mycobacteriophage before viricide treatment; and (iii) a further 90-min incubation after viricide treatment and neutralization up to the burst time (total incubation time, 210 min) before plating with M. smegmatis mc(2) 155 in 7H9 agar. The optimized phage amplification assay was able to detect 1 to 10 CFU/ml of M. avium subsp. paratuberculosis in spiked milk or broth within 48 h, as demonstrated by the results of several blind trials.

Contamination of food products with Mycobacterium avium paratuberculosis: a systematic review

Although a causal link between Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn's disease has not been proved, previous studies suggest that the potential routes of human exposure to MAP should be investigated. We conducted a systematic review of literature concerning the likelihood of contamination of food products with MAP and the likely changes in the quantity of MAP in dairy and meat products along their respective production chains. Relevant data were extracted from 65 research papers and synthesized qualitatively. Although estimates of the prevalence of Johne's disease are scarce, particularly for non-dairy herds, the available data suggest that the likelihood of contamination of raw milk with MAP in most studied regions is substantial. The presence of MAP in raw and pasteurized milk has been the subject of several studies which show that pasteurized milk is not always MAP-free and that the effectiveness of pasteurization in inactivating MAP depends on the initial concentration of the agent in raw milk. The most recent studies indicated that beef can be contaminated with MAP via dissemination of the pathogen in the tissues of infected animals. Currently available data suggests that the likelihood of dairy and meat products being contaminated with MAP on retail sale should not be ignored.

Pathogenic ‘Bison-type’ Mycobacterium avium subspecies paratuberculosis genotype characterized from riverine buffalo (Bubalus bubalis) in North India

Despite low per-animal productivity of ruminants in developing countries, Johne's disease has not been investigated in buffaloes, which are primarily found in these countries. This is due to lack of expertise, diagnostic kits and priority to production diseases like Johne's disease. Presence of pathogenic Mycobacterium avium subspecies paratuberculosis (Map) was investigated by screening of target tissues (mesenteric lymph nodes and large intestine) by culture and IS 900 PCR, in 50 sacrificed buffaloes. Indigenous ELISA kit originally developed for goats and sheep was standardized in buffaloes and used to estimate sero-presence of Map in 167 serum samples representing population of buffaloes in Agra region of North India. In culture, 48.0% buffaloes were positive from 50 tissues each from mesenteric lymph nodes (34.0%) and large intestine (36.0%). IS 900 PCR was standardized using specific primers (150 C and 921) and 229 bp-amplified product was characteristic for Map. Of the 25 mesenteric lymph nodes, 40.0% were positive in IS 900 PCR. Genomic DNA from Map cultures was successfully amplified from all the 24 isolates (100.0%). Map was further genotyped as 'Bison type' using IS 1311 PCR-REA. Culture of tissues showed high presence of Map in target tissues, despite high culling rate in buffalos in view of high demand of buffalo meat. Specific tissue-PCR provided rapid confirmation of Map infection in sacrificed buffaloes. In tissue-PCR, all the cultures were positive as compared to 40.0% detected directly from tissues. ELISA kit using indigenous protoplasmic antigen was highly sensitive as compared to commercial antigen in detecting Map infection therefore, could be used as 'Herd Screening Test' in buffaloes against Johne's disease. This pilot study first time reports a highly pathogenic 'Bison-type' genotype of M. avium subspecies paratuberculosis from the riverine buffaloes (Bubalus bubalis) of Agra region in North India.

Mycobacterium avium subspecies paratuberculosis and Crohn's disease: a systematic review and meta-analysis

This systematic review assesses the evidence for an association between Mycobacterium avium subspecies paratuberculosis (MAP) and Crohn's disease. We analysed 28 case-control studies comparing MAP in patients with Crohn's disease with individuals free of inflammatory bowel disease (IBD) or patients with ulcerative colitis. Compared with individuals free of IBD, the pooled odds ratio (OR) from studies using PCR in tissue samples was 7.01 (95% CI 3.95-12.4) and was 1.72 (1.02-2.90) in studies using ELISA in serum. ORs were similar for comparisons with ulcerative colitis patients (PCR, 4.13 [1.57-10.9]; ELISA, 1.88 [1.26-2.81]). The association of MAP with Crohn's disease seems to be specific, but its role in the aetiology of Crohn's disease remains to be defined.

Prevalence of Mycobacterium avium Subspecies paratuberculosis in Swiss Raw Milk Cheeses Collected at the Retail Level

A total of 143 raw milk cheese samples (soft cheese, n = 9; semihard cheese, n = 133; hard cheese, n = 1), collected at the retail level throughout Switzerland, were tested for Mycobacterium avium ssp. paratuberculosis (MAP) by immunomagnetic capture plus culture on 7H10-PANTA medium and in supplemented BAC-TEC 12B medium, as well as by an F57-based real-time PCR system. Furthermore, pH and water activity values were determined for each sample. Although no viable MAP cells could be cultured, 4.2% of the raw milk cheese samples tested positive with the F57-based real-time PCR system, providing evidence for the presence of MAP in the raw material. As long as the link between MAP and Crohn's disease in humans remains unclear, measures designed to minimize public exposure should also include a focus on milk products.

Inactivation of Mycobacterium avium subsp. paratuberculosis in cow's milk by means of high hydrostatic pressure at mild temperatures

Two strains of Mycobacterium avium subsp. paratuberculosis (3644/02 and ATCC 19698) were inoculated (approximately 6 log CFU/ml) into sterilized milk to evaluate inactivation by high hydrostatic pressure. Reductions of M. avium subsp. paratuberculosis increased with pressure level. Significant differences were also found between M. avium subsp. paratuberculosis strains and between the media used. Average reductions of 4 log CFU/ml after treatment with 500 MPa are comparable to those caused by thermal treatments.