Viable Mycobacterium avium ssp. paratuberculosis isolated from calf milk replacer

Management and housing factors associated with paratuberculosis-positive herds in small structured alpine cattle husbandry

Paratuberculosis (Johne´s disease) is a world-wide cattle disease caused by Mycobacterium avium subsp. paratuberculosis (MAP), associated with substantial economic losses. Purchase of subclinically infected animals or contact with animals and equipment of infected farms are known risk factors for disease transmission among herds. The aim of the present study was to identify specific management factors in Austria that triggered a MAP-positive herd status and to evaluate known risk factors for the transmission in cattle in small structured alpine agricultural systems. The agriculture in the Austrian province of Tyrol is characterized by smallholder structures, including shared alpine pastures and traditional barn management techniques. The data from an extensive survey with 50 questions in 2013/2014 and the development of the MAP herd status of 5592 cattle farms by taking feces and blood samples were examined and statistically evaluated. MAP herd status was determined by combining the results of boot swab samples, manure samples, pooled and individual feces samples as well as serological antibody testing by ELISA. The statistical analysis (odds ratio; OR) showed that the use of milk replacers for calf feeding (p = 0.047, OR=0.472) and the use of straw as bedding material for cows (p = 0.032, OR=0.625) were associated with a decreased chance of being a MAP-positive herd. Further, housing cows in deep litter systems (p = 0.028, OR=2.232), the presence of slurry channels (p = 0.028, OR=1.411) and the use of solid manure in young cattle (p = 0.041, OR=1.744) were associated with an increased OR for being MAP-positive. Surprisingly, sharing of lowland pastures (p = 0.564, OR=1.080), alpine pastures (p = 0.419, OR=1.143) or farm equipment (p = 0.733, OR=0.963) and farm size (p = 0.425) had no significant influence on the MAP herd status. The identified differences compared with previously published results in respect of MAP spread in cattle might be attributed to the traditional agricultural structures, including small family-based farms and common pasture during summer in alpine regions. Results of this study contribute to the understanding of the spread of MAP in cattle farming in alpine regions.

Application of the Actiphage® Assay to Detect Viable Mycobacterium avium subsp. paratuberculosis Cells in Fresh Sheep and Goat Milk and Previously Frozen Milk and In-Line Milk Filters

Mycobacterium avium subsp. paratuberculosis (MAP) is a well-known causative agent of paratuberculosis, a chronic infectious granulomatous enteritis of ruminants contributing to significant economic losses worldwide. Current conventional diagnostic tools are far from being sufficient to manage and control this disease. Therefore, increased attention has been paid to alternative approaches including phage-based assays employing lytic bacteriophage D29 to detect MAP cells. The aim of the present study was to assess the applicability and efficiency of the recently developed phage-based kit termed Actiphage® combined with IS900 real-time PCR (qPCR) for rapid detection and quantification of viable MAP in milk samples. We demonstrated that Actiphage® in combination with IS900 qPCR allows for rapid and sensitive detection and identification of viable MAP in milk samples with a limit of detection of 1 MAP per 50 ml milk. Using this method, the presence of viable MAP cells was successfully determined in 30.77% of fresh goat, sheep and cow milk samples originating from paratuberculosis-affected herds. We further used Actiphage assay to define the time-lapse aspect of testing naturally contaminated milk and milk filters frozen for various lengths of time by phage-based techniques. Viable MAP was detected in 13.04% of frozen milk samples and 28.57% of frozen milk filters using Actiphage-qPCR. The results suggest the ability to detect viable MAP in these samples following freezing for more than 1 year. The obtained results support the views of the beneficial role of this technology in the control or monitoring of paratuberculosis.

Johne's Disease in Dairy Cattle: An Immunogenetic Perspective

Johne's disease (JD), also known as paratuberculosis, is a severe production-limiting disease with significant economic and welfare implications for the global cattle industry. Caused by infection with Mycobacterium avium subspecies paratuberculosis (MAP), JD manifests as chronic enteritis in infected cattle. In addition to the economic losses and animal welfare issues associated with JD, MAP has attracted public health concerns with potential association with Crohn's disease, a human inflammatory bowel disease. The lack of effective treatment options, such as a vaccine, has hampered JD control resulting in its increasing global prevalence. The disease was first reported in 1895, but in recognition of its growing economic impact, extensive recent research facilitated by a revolution in technological approaches has led to significantly enhanced understanding of the immunological, genetic, and pathogen factors influencing disease pathogenesis. This knowledge has been derived from a variety of diverse models to elucidate host-pathogen interactions including in vivo and in vitro experimental infection models, studies measuring immune parameters in naturally-infected animals, and by studies conducted at the population level to enable the estimation of genetic parameters, and the identification of genetic markers and quantitative trait loci (QTL) putatively associated with susceptibility or resistance to JD. The main objectives of this review are to summarize these recent developments from an immunogenetics perspective and attempt to extract the principal and common findings emerging from this wealth of recent information. Based on these analyses, and in light of emerging technologies such as gene-editing, we conclude by discussing potential future avenues for effectively mitigating JD in cattle.

Attempted Control of Paratuberculosis in Dairy Calves by Only Changing the Quality of Milk Fed to Calves

One of the important routes of Mycobacterium avium subsp. paratuberculosis (MAP) transmission in dairy calves is milk. The aim of the present study was to assess the efficacy of milk treatments to prevent MAP infection transmission to calves. A one-year longitudinal study was carried out. Newborn calves were assigned to one of four experimental groups: 5 calves received naturally MAP-contaminated milk, 5 calves received copper treated milk, 4 calves were fed calf milk replacer, and 3 were fed UHT pasteurized milk. MAP load in milk was estimated. Infection progression was monitored monthly. After one year, calves were euthanized, and tissue samples were cultured and visually examined. MAP was undetectable in milk replacer and UHT milk. Copper ion treatment significantly reduced the number of viable MAP in naturally contaminated milk. Fecal shedding of MAP was observed in all study groups but began earlier in calves fed naturally contaminated milk. Paratuberculosis control programs must place multiple hurdles between the infection source, MAP-infected adult cows, and the most susceptible animals on the farm, young calves. As our study shows, strict dependence on a single intervention to block infection transmission, no matter how important, fails to control this insidious infection on dairy farms.

Phage Amplification Assay for Detection of Mycobacterial Infection: A Review

An important prerequisite for the effective control, timely diagnosis, and successful treatment of mycobacterial infections in both humans and animals is a rapid, specific, and sensitive detection technique. Culture is still considered the gold standard in the detection of viable mycobacteria; however, mycobacteria are extremely fastidious and slow-growing microorganisms, and therefore cultivation requires a very long incubation period to obtain results. Polymerase Chain Reaction (PCR) methods are also frequently used in the diagnosis of mycobacterial infections, providing faster and more accurate results, but are unable to distinguish between a viable and non-viable microorganism, which results in an inability to determine the success of tuberculosis patient treatment or to differentiate between an active and passive infection of animals. One suitable technique that overcomes these shortcomings mentioned is the phage amplification assay (PA). PA specifically detects viable mycobacteria present in a sample within 48 h using a lytic bacteriophage isolated from the environment. Nowadays, an alternative approach to PA, a commercial kit called Actiphage™, is also employed, providing the result within 6–8 h. In this approach, the bacteriophage is used to lyse mycobacterial cells present in the sample, and the released DNA is subsequently detected by PCR. The objective of this review is to summarize information based on the PA used for detection of mycobacteria significant in both human and veterinary medicine from various kinds of matrices.

Presence of Infection by Mycobacterium avium subsp. paratuberculosis in the Blood of Patients with Crohn's Disease and Control Subjects Shown by Multiple Laboratory Culture and Antibody Methods

Mycobacterium avium subspecies paratuberculosis (MAP) has long been suspected to be involved in the etiology of Crohn's disease (CD). An obligate intracellular pathogen, MAP persists and influences host macrophages. The primary goals of this study were to test new rapid culture methods for MAP in human subjects and to assess the degree of viable culturable MAP bacteremia in CD patients compared to controls. A secondary goal was to compare the efficacy of three culture methods plus a phage assay and four antibody assays performed in separate laboratories, to detect MAP from the parallel samples. Culture and serological MAP testing was performed blind on whole blood samples obtained from 201 subjects including 61 CD patients (two of the patients with CD had concurrent ulcerative colitis (UC)) and 140 non-CD controls (14 patients in this group had UC only). Viable MAP bacteremia was detected in a significant number of study subjects across all groups. This included Pozzato culture (124/201 or 62% of all subjects, 35/61 or 57% of CD patients), Phage assay (113/201 or 56% of all subjects, 28/61 or 46% of CD patients), TiKa culture (64/201 or 32% of all subjects, 22/61 or 36% of CD patients) and MGIT culture (36/201 or 18% of all subjects, 15/61 or 25% of CD patients). A link between MAP detection and CD was observed with MGIT culture and one of the antibody methods (Hsp65) confirming previous studies. Other detection methods showed no association between any of the groups tested. Nine subjects with a positive Phage assay (4/9) or MAP culture (5/9) were again positive with the Phage assay one year later. This study highlights viable MAP bacteremia is widespread in the study population including CD patients, those with other autoimmune conditions and asymptomatic healthy subjects.

Effectiveness of copper ions against Mycobacterium avium subsp. paratuberculosis and bacterial communities in naturally contaminated raw cow's milk

AIM

The focus of the present study was to evaluate the copper ions treatment on the viability of Mycobacterium avium subsp. paratuberculosis (MAP) and other bacterial communities in cow's milk.

METHODS AND RESULTS

A copper ions treatment was evaluated in naturally contaminated cow's milk to assay MAP load and/or viability, and relative abundance of other bacterial communities. In addition, physical-chemical analyses of the milk were also performed. All analyses were carried out before and after a copper ions treatment. After copper ions treatment, pH and copper concentration markedly increased in milk; the numbers of viable MAP significantly decreased. The relative abundance of the four target phyla decreased, with the phyla Bacteroidetes and Firmicutes surviving treatment in higher proportions (4 and 2·1% of original populations, respectively). A progressively higher percentage of dead bacterial cells after 5 and 20 min copper ions treatments was found (12 and 35%, respectively).

CONCLUSION

With the exception of some MAP-tolerant strains, we have once again demonstrated that copper ions have a significant inactivating effect on MAP as well as certain other bacterial communities found in naturally contaminated cow's milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study showed a significant inactivation of both MAP and other bacteria by copper ions in raw cow's milk, information that could be useful as a tool for MAP control.

A novel one-day phage-based test for rapid detection and enumeration of viable Mycobacterium avium subsp. paratuberculosis in cows' milk

Bacteriophage-based methods for the rapid detection of viable Mycobacterium avium subsp. paratuberculosis (MAP) in veterinary specimens are a recent addition to the Johne's disease diagnostic toolbox. Here, we report the use of D29 mycobacteriophage-coated tosylactivated paramagnetic beads to capture and concentrate MAP cells from samples (termed phagomagnetic separation, PhMS) and then naturally lyse viable MAP cells (from the inside out) to provide DNA for IS900 qPCR purposes. Transmission electron microscopy confirmed that D29 phages had bound to beads in the correct orientation and that the phage-coated beads captured MAP cells from a suspension. During test optimization, conventional IS900 PCR results were used to subjectively assess the effect of different phage:bead coating ratios, differing amounts of coated beads during PhMS, optimal incubation time post-PhMS to obtain maximal MAP DNA, and the potential benefit of a brief heat shock (55 °C/1 min) prior to IS900 TaqMan qPCR. The limit of detection 50% (LOD50%) of the optimised PhMS-qPCR assay was 10.00 MAP cells/50 ml milk (95% CI 1.20-82.83). Finally, in order to demonstrate the new assay's ability to detect viable MAP in naturally contaminated milk, bulk tank milk samples from 100 dairy farms were tested. Forty-nine (49%) of these tested PhMS-qPCR-positive, with viable MAP numbers detected ranging from 3-126 MAP/50 ml. The novel PhMS-qPCR assay is a sensitive, specific and easy-to-apply phage-based assay for viable MAP, with potential application for milk surveillance or diagnosis of Johne's disease. KEY POINTS: • Phage-coated magnetic beads could capture, concentrate and lyse MAP cells from milk. • PhMS-qPCR assay proved to be a rapid, sensitive and specific test for viable MAP. • A potential application of PhMS-qPCR assay for milk surveillance was demonstrated.

Seroprevalence of Immunoglobulin G Antibodies Against Mycobacterium avium subsp. paratuberculosis in Dogs Bred in Japan

In this study, the seroprevalence of immunoglobulin G (IgG) antibodies against Mycobacterium avium subsp. paratuberculosis (MAP) in dogs bred in Japan was evaluated. Ninety-two non-clinical samples were obtained from three institutes and fifty-seven clinical samples were obtained from a veterinary hospital in Japan. Serum titers of total IgG, IgG₁ and IgG₂ isotype antibodies against MAP were measured using an indirect enzyme-linked immunosorbent assay (ELISA). The IgG antibodies against MAP in non-clinical serum obtained from three institutes was observed to be 2.4%, 20% and 9.0%. Similarly, the IgG₁ antibodies titers against MAP were observed to be 7%, 20% and 0%. Lastly, the IgG₂ antibodies against MAP were observed to be 7%, 20% and 4.4%. No significance differences in these titers were observed among the three institutes. The IgG, IgG₁ and IgG₂ antibodies in serum obtained from a veterinary hospital were observed to be 55.3%, 42% and 42%, respectively. Significant differences were found between the non-clinical and clinical samples. The titers in the clinical samples showed a high degree of variance, whereas low variance was found in the non-clinical samples. The IgG antibody levels were thought to be induced following exposure to MAP-contaminated feed. The difference in titers between the clinical and non-clinical samples is likely to be related to the amount of MAP antigen contamination in dog foods.

Paratuberculosis: A Potential Zoonosis and a Neglected Disease in Africa

The Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of paratuberculosis, which is an economically important disease of ruminants. The zoonotic role of MAP in Crohn’s disease and, to a lesser extent, in ulcerative colitis, the two major forms of idiopathic inflammatory bowel disease (IIBD), has been debated for decades and evidence continues to mount in support of that hypothesis. The aim of this paper is to present a review of the current information on paratuberculosis in animals and the two major forms of IIBD in Africa. The occurrence, epidemiology, economic significance and “control of MAP and its involvement IIBD in Africa” are discussed. Although the occurrence of MAP is worldwide and has been documented in several African countries, the epidemiology and socioeconomic impacts remain undetermined and limited research information is available from the continent. At present, there are still significant knowledge gaps in all these areas as far as Africa is concerned. Due to the limited research on paratuberculosis in Africa, in spite of growing global concerns, it may rightfully be considered a neglected tropical disease with a potentially zoonotic role.

Seroprevalence of anti-Mycobacterium avium subsp. paratuberculosis antibodies in female sheep in Tunisia

Paratuberculosis (Ptb) is a widespread chronic infection caused by Mycobacterium avium subsp. paratuberculosis (Map) that affects both domestic and wild ruminants. Most of the studies focused on cattle while, the prevalence of Ptb in sheep in different regions of the world is not well investigated. This study aimed to address this gap of knowledge by screening adult female sheep for paratuberculosis antibodies in different geographical regions of Tunisia. A total number of 338 female sheep from 15 small to middle-sized, extensively managed sheep farms in six regions across Tunisia were sampled. Animals were clinically examined before blood sampling. Sera were tested for the presence of anti-Mycobacterium avium subsp. paratuberculosis antibodies using a commercial ELISA kit. Six farms out of 15 comprised at least one seropositive animal and 11 female sheep out of 338 tested animals (3.25%; 95% CI = [1.83-5.73]) were seropositive to M. avium subsp. paratuberculosis. The seroprevalence was significantly lower in 5-year-old females (p = .04) and animals that do not graze (p = .02). Due to its huge economic and social impacts, paratuberculosis represents a health problem in Tunisia and several other countries Further investigations are needed to rank sheep Ptb in Tunisia among other diseases and to assess the main risk factors using a larger nation-wide survey.

Is the transmission of Mycobacterium avium subspecies paratuberculosis (MAP) infection through milk intended to feed calves an overlooked item in paratuberculosis control programs?

As in many parts of the world, Chile shows a high Mycobacterium avium subsp. paratuberculosis (MAP) infection rate. Evidently, the control recommendations have been inefficient. In the author's opinion, the potential risk of MAP transmission to susceptible calves through milk consumption is largely overlooked. Two observational studies were performed, one to confirm MAP shedding in young stock in a high MAP-infected dairy herd and MAP load in milk intended to feed these calves was estimated. In parallel, in a second study, we estimated the relationship between MAP herd seroprevalence and the cow MAP shedding level as well as the presence of this pathogen in milk used to feed dairy calves. In the first study, 53.7% of cows and 22.5% of calves showed positive culture results. Among all cows tested, 9 (2.19%) animals had a positive serum ELISA, and MAP load in milk reached 10⁶ bacteria/mL. In the second study, three seroprevalence categories were established as follows: high (≥ 9%), medium (> 5% and ≤ 9%), and low (≤ 5%). Statistical significant differences among these categories were observed. Animals from the high seroprevalence category shed significantly more MAP than the others. However, in the low category, heavy shedder animals were also observed. Finally, in all study herds, MAP presence in milk intended to feed calves was reported, even from herds without ELISA-positive animals.

The inhibitory effect of nisin on Mycobacterium avium ssp. paratuberculosis and its effect on mycobacterial cell wall

Infection with Mycobacterium avium ssp. paratuberculosis (M. paratuberculosis) is a widespread problem in the United States and worldwide, and it constitutes a significant health problem for dairy animals with a potential effect on human health. Mycobacterium paratuberculosis is easily transmitted through consumption of contaminated milk; therefore, finding safe methods to reduce the mycobacterial load in milk and other dairy products is important to the dairy industry. The main objective of the current study was to investigate the effect of natural products, such as bacteriocins designated as "generally regarded as safe" (GRAS), on the survival of M. paratuberculosis in milk. Commercially synthesized bacteriocin (nisin) was used to examine its effect on the survival of laboratory and field isolates of M. paratuberculosis and in contaminated milk. Surprisingly, nisin had a higher minimum inhibitory concentration (MIC) against the laboratory strain (M. paratuberculosis K10), at 500 U/mL, than against field isolates (e.g., M. paratuberculosis 4B and JTC 1281), at 15 U/mL. In milk, growth of M. paratuberculosis was inhibited after treatment with levels of nisin that are permissible in human food at 4°C and 37°C. Using both fluorescent and scanning electron microscopy, we were able to identify defects in the bacterial cell walls of treated cultures. Our analysis indicated that nisin reduced membrane integrity by forming pores in the mycobacterial cell wall, thereby decreasing survival of M. paratuberculosis. Thus, nisin treatment of milk could be implemented as a control measure to reduce M. paratuberculosis secreted in milk from infected herds. Nisin could also be used to reduce M. paratuberculosis in colostrum given to calves from infected animals, improving biosecurity control in dairy herds affected by Johne's disease.

Prevalence of Mycobacterium avium subspecies paratuberculosis IS 900 DNA in biopsy tissues from patients with Crohn's disease: histopathological and molecular comparison with Johne's disease in Fars province of Iran

BACKGROUND

Crohn's disease is a chronic enteritis of humans that affects the gastrointestinal tract, especially the terminal ileum, cecum and colon. The etiology of this disease is still unknown but seems to be multifactorial. There are reports about the potential link between Crohn's disease in humans and the causative agent of Johne's disease in ruminants. Because of the prevalence of Johne's disease in the Fars Province of Iran, the aim of this study was to investigate the prevalence of MAP in the biopsy tissues of patients affected by Crohn's disease in this area.

METHODS

The study was performed from April 2015 to June 2017 at Namazi Hospital, Shiraz University of Medical Sciences, and School of Veterinary Medicine, Shiraz University, Shiraz, Iran. Intestinal biopsies of 30 patients (12 male and 18 female; mean age, 34 years; range 4-77 years) with the confirmed diagnosis of Crohn's disease and 30 patients diagnosed as non-inflammatory bowel disease (19 male and 11 female; mean age, 38 years; range 13-68 years) were studied by molecular, histopathological and histochemical methods. Also, similar numbers of adult goats affected by Johne's disease were studied, comparatively. DNA extractions of tissue specimens were subjected to PCR to amplify a 413-bp sequence of the IS900 gene.

RESULTS

Using IS900-PCR, the overall prevalence of MAP in patients affected by Crohn's disease and non-inflammatory bowel disease were 47 and 13%, respectively. In addition, the prevalence of MAP in goats affected by Johne's disease was 70%. Using acid-fast histochemical staining, only 7% of Crohn's disease patients were weakly positive as paucibacillary and 43% of Johne's disease cases were moderate to strongly positive as multibacillary. Histopathologically, granulomatous enteritis (83 and 90%), lymphoplasmacytic enteritis (17 and 14%), edema and lymphangiectasia (67 and 96%), and vasculitis (20 and 73%) were common findings in Crohn's and Johne's diseases, respectively.

CONCLUSION

Our findings demonstrate a remarkable association between MAP and CD in this population, and support an etiologic relationship between MAP infection in humans and the development of CD. MAP infection in human tissue may display species-specific pathologic findings, as occurs with other zoonotic pathogens.

In vitro inactivation of Mycobacterium avium subsp. paratuberculosis (MAP) by use of copper ions

Background

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a contagious infectious disease that affects domestic and wild ruminants causing chronic inflammation of the intestine. MAP has proven to be very resistant to both physical and chemical processes, making it difficult to control this pathogen. Based on the recognized antimicrobial properties of copper, the objective of this study was to evaluate the effectiveness of copper ions to reduce MAP numbers and/or MAP viability in a fluid matrix. Besides, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli were used as controls of the effectiveness of copper ions. MAP-spiked PBS was subjected to copper ions treatment at 24 V for 5 min and the PBS suspensions were sampled before and after treatment. MAP viability and quantification were determined using three complementary techniques: a phage amplification assay, MGIT culture and qPCR.

Results

Moderate numbers (10³ CFU ml⁻¹) of the two control bacteria were completely eliminated by treatment with copper ions. For MAP, copper ions treatment reduced both the viability and numbers of this pathogen. Phage assay information quickly showed that copper ions (24 V for 5 min) resulted in a significant reduction in viable MAP. MGIT culture results over time showed statistically significant differences in time-to-detection (TTD) values between PRE and POST treatment. MAP genome equivalent estimates for PBS suspensions indicated that MAP numbers were lower in samples POST-treatment with copper ions than PRE-treatment.

Conclusions

The use of copper ions resulted in a significant reduction of MAP in a liquid matrix, although some MAP survival on some occasions was observed.