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Kuhnert P, Loosli N, Brodard I, Lindtke D, Jores J. Resistance of zebu cattle (Bos indicus) to colonization by major ruminant hoof pathogens. Vet Microbiol 2024; 296:110184. [PMID: 38996749 DOI: 10.1016/j.vetmic.2024.110184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 07/05/2024] [Accepted: 07/09/2024] [Indexed: 07/14/2024]
Abstract
Zebu cattle (Bos indicus) is reported to be more resistant towards harmful environmental factors than taurine cattle (Bos taurus). A few hundred zebu cattle are kept in Switzerland and in contrast to the Swiss indigenous breeds, infectious hoof disease in zebu is not observed. Therefore, we compared the prevalence of three ruminant hoof pathogens in zebu and taurine cattle. These included Treponema spp., Fusobacterium necrophorum and Dichelobacter nodosus which are associated with bovine digital dermatitis (BDD), different bovine hoof diseases and ovine footrot, respectively. Interdigital swabs and punch biopsies from hind feet of slaughter animals were tested for the three pathogens by PCR. Sixty zebu from eight farms were compared to a convenience sample of 20 taurine cattle from 17 farms. Treponema spp. associated with BDD were not detected in zebu while 23 % of animals and 50 % of farms were positive for benign D. nodosus, with results indicating environmental contamination rather than colonization. Taurine cattle showed 35 % of animals and 41 % of farms positive for T. phagedenis while 90 % of animals and 94 % of farms were colonized by D. nodosus as indicated by a 500-fold higher bacterial load than in zebu. The difference in prevalence of the two pathogens between zebu and taurine cattle was highly significant. F. necrophorum was as well only detected in taurine cattle with values of 15 % of animals and 17.7 % of farms, being significantly different at the animal level. Furthermore, genetic analysis of Swiss zebu indicates high genomic diversity and clear separation from taurine cattle. This is the first evidence that zebu show resistance towards colonization by bacterial hoof pathogens in contrast to taurine cattle.
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Affiliation(s)
- Peter Kuhnert
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, Bern 3012, Switzerland.
| | - Nadia Loosli
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, Bern 3012, Switzerland
| | - Isabelle Brodard
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, Bern 3012, Switzerland
| | | | - Joerg Jores
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, Bern 3012, Switzerland
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Schmid RM, Steiner A, Becker J, Baumberger S, Dürr S, Alsaaod M. Field Validation of a Non-carcinogenic and Eco-Friendly Disinfectant in a Stand-In Footbath for Treatment of Footrot Associated With aprV2-Positive Strains of Dichelobacter nodosus in Swiss Sheep Flocks. Front Vet Sci 2022; 9:812638. [PMID: 35774977 PMCID: PMC9237958 DOI: 10.3389/fvets.2022.812638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 03/30/2022] [Indexed: 11/13/2022] Open
Abstract
A national control program for virulent footrot is currently planned in Switzerland. Since commonly used disinfectants either contain heavy metals or are carcinogenic, the aim of this study was to verify the effectiveness of an eco-friendly and non-carcinogenic candidate disinfectant against aprV2-positive strains of Dichelobacter nodosus. Additionally, the effect of the selective use of long-acting oxytetracyclines was evaluated. A total of 18 farms with confirmed footrot infection, randomly allocated to two treatment groups: (1) with antibiotics (AB; n = 9) and, (2) no antibiotics (NAB; n = 9), were included. Claws were carefully trimmed and scored using a scale from 0 (clinically healthy) to 5 (complete loss of the horn capsule) and a prewash waterbath was implemented on 11 farms. Twice-weekly, repeated whole-flock stand-in footbaths with the candidate disinfectant (6%) were performed. Additionally, animals of group AB with a score ≥ 3 were administered oxytetracyclines by injection. On all farms, 10 days after last treatment, aprV2-positive strains could not be detected by risk-based sampling for real-time PCR analysis after 7–21 (median = 12) footbaths with a minimal culling rate of non-responders on nine farms. Farms without contact to other sheep remained without clinical signs of footrot for a minimum of 245 days (mean ± standard deviation: 293.6 ± 23.6). Antibiotic treatment did not reduce the number of footbaths needed. In contrast, a mean of 3.3 disinfecting footbaths could be saved by implementing a prewash waterbath. At animal level, individual and selective use of oxytetracyclines lead to a higher chance (odds ratio = 9.95; 95% CI: 3.54–27.95; p < 0.001) for a lesion score ≥ 3 to improve to a lesion score < 3 within 2 weeks compared to treatment without antibiotics. The test disinfectant is an effective and eco-friendly alternative for the planned Swiss footrot control program and selective use of oxytetracycline has a beneficial impact on the recovery of animals with lesion scores ≥ 3.
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Affiliation(s)
- Robin Michael Schmid
- Clinic for Ruminants, Department of Clinical Veterinary Science, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Adrian Steiner
- Clinic for Ruminants, Department of Clinical Veterinary Science, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Jens Becker
- Clinic for Ruminants, Department of Clinical Veterinary Science, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Sandra Baumberger
- Clinic for Ruminants, Department of Clinical Veterinary Science, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Salome Dürr
- Veterinary Public Health Institute, Department of Clinical Research and Veterinary Public Health, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Maher Alsaaod
- Clinic for Ruminants, Department of Clinical Veterinary Science, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
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3
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Albuquerque C, Cavaco S, Caetano P, Branco S, Monteiro H, Ramos M, Usié Chimenos A, Leão C, Botelho A. Ovine footrot in Southern Portugal: Detection of Dichelobacter nodosus and Fusobacterium necrophorum in sheep with different lesion scores. Vet Microbiol 2022; 266:109339. [DOI: 10.1016/j.vetmic.2022.109339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 08/06/2021] [Accepted: 01/09/2022] [Indexed: 10/19/2022]
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Blanchard AM, Staley CE, Shaw L, Wattegedera SR, Baumbach CM, Michler JK, Rutland C, Back C, Newbold N, Entrican G, Tötemeyer S. A Trifecta of New Insights into Ovine Footrot for Infection Drivers, Immune Response, and Host-Pathogen Interactions. Infect Immun 2021; 89:e0027021. [PMID: 34227837 PMCID: PMC8445190 DOI: 10.1128/iai.00270-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 06/16/2021] [Indexed: 12/02/2022] Open
Abstract
Footrot is a polymicrobial infectious disease in sheep causing severe lameness, leading to one of the industry's largest welfare problems. The complex etiology of footrot makes in situ or in vitro investigations difficult. Computational methods offer a solution to understanding the bacteria involved and how they may interact with the host, ultimately providing a way to identify targets for future hypothesis-driven investigative work. Here, we present the first combined global analysis of bacterial community transcripts together with the host immune response in healthy and diseased ovine feet during a natural polymicrobial infection state using metatranscriptomics. The intratissue and surface bacterial populations and the most abundant bacterial transcriptomes were analyzed, demonstrating that footrot-affected skin has reduced diversity and increased abundances of not only the causative bacterium Dichelobacter nodosus but also other species such as Mycoplasma fermentans and Porphyromonas asaccharolytica. Host transcriptomics reveals the suppression of biological processes related to skin barrier function, vascular functions, and immunosurveillance in unhealthy interdigital skin, supported by histological findings that type I collagen (associated with scar tissue formation) is significantly increased in footrot-affected interdigital skin compared to outwardly healthy skin. Finally, we provide some interesting indications of host and pathogen interactions associated with virulence genes and the host spliceosome, which could lead to the identification of future therapeutic targets.
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Affiliation(s)
- Adam M. Blanchard
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
| | - Ceri E. Staley
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
| | - Laurence Shaw
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Sean R. Wattegedera
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, Scotland
| | - Christina-Marie Baumbach
- Institute of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Jule K. Michler
- Institute of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Catrin Rutland
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
| | - Charlotte Back
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
| | - Nerissa Newbold
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
| | - Gary Entrican
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Midlothian, Scotland
| | - Sabine Tötemeyer
- School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom
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Monaghan EM, Prosser NS, Witt J, Lewis KE, Nabb E, Keeling MJ, Purdy KJ, Green LE. Impact of Strain Variation of Dichelobacter nodosus on Disease Severity and Presence in Sheep Flocks in England. Front Vet Sci 2021; 8:713927. [PMID: 34485440 PMCID: PMC8415419 DOI: 10.3389/fvets.2021.713927] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
AprV2 and aprB2 are variants of the apr gene of Dichelobacter nodosus, the cause of footrot in sheep. They are putative markers for severe and mild disease expression. The aim of our study was to investigate the distribution of aprV2 and aprB2 in flocks with and without footrot. Our hypotheses were that both strains are present in endemically affected flocks, with aprB2 and aprV2 associated with mild and virulent phenotypes respectively but that D. nodosus is not present in flocks without footrot. Alternatively, aprB2 persists in flocks without footrot. Despite extensive searching over 3 years only three flocks of sheep without footrot were identified. D. nodosus was not detected in these three flocks. In one further flock, only mild interdigital dermatitis was observed, and only aprB2 was detected. Twenty-four flocks with endemic footrot of all severities were sampled on three occasions and all were positive for D. nodosus and the aprV2 variant; aprB2 was detected in only 11 of these flocks. AprB2 was detected as a co-infection with aprV2 in the 22% of samples positive for aprB2 and was more likely in mild footrot phenotypes than severe. Dichelobacter nodosus serogroups were not associated with footrot phenotype. We conclude that D. nodosus, even aprB2 strains, do not persist in flocks in the absence of footrot. Our results support the hypothesis that aprB2 is associated with mild footrot phenotypes. Finally, we conclude that given the small number of flocks without footrot that were identified, footrot is highly endemic in English sheep flocks.
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Affiliation(s)
- Emma M Monaghan
- Institute of Microbiology and Infection, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Naomi S Prosser
- School of Veterinary Medicine and Science, University of Nottingham, Leicestershire, United Kingdom
| | - Jessica Witt
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Katharine E Lewis
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Elizabeth Nabb
- Institute of Microbiology and Infection, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Matt J Keeling
- Zeeman Institute, SBIDER: Systems Biology & Infectious Disease Epidemiology Research, Warwick Mathematics Institute, University of Warwick, Coventry, United Kingdom
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Laura E Green
- Institute of Microbiology and Infection, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
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Hoby S, Jensen TK, Brodard I, Gurtner C, Eicher R, Steiner A, Kuhnert P, Alsaaod M. Detection of treponemes in digital dermatitis lesions of captive European bison (Bison bonasus). PLoS One 2021; 16:e0255921. [PMID: 34370779 PMCID: PMC8352065 DOI: 10.1371/journal.pone.0255921] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 07/26/2021] [Indexed: 11/19/2022] Open
Abstract
A newly-discovered foot disease of unknown origin in captive European Bison (Bison bonasus) was recently detected at Berne Animal Park. Dermatitis of the interdigital cleft of varying degrees of severity was diagnosed in all animals (n = 10). The aim of this study was to describe the gross and histological lesions of the interdigital cleft found in 10 captive European bison and to identify involved potential pathogens in affected feet using molecular-based methods for Treponema spp., Dichelobacter nodosus and Fusobacterium necrophorum. Lesions were scored according to the degree of gross pathology at limb level. In a single animal, the gross lesions were restricted to focal lesions on the dorsal aspect of the digital skin of each foot (score 1), whereas all other animals showed at least one foot with extended lesions including the interdigital cleft (score 2). The presence of viable spirochaetes was observed in all animals using dark field microscopy. Applying fluorescence in situ hybridisation (FISH) on biopsies, Treponema spp. were identified, infiltrating the skin lesions in varying numbers in nine animals. Nested PCRs for Treponema medium, Treponema phagedenis and Treponema pedis of swab samples showed three positive animals out of ten for the latter two, whereas pooled biopsy samples were positive in all ten animals for at least T. phagedenis (9/10) and/or T. pedis (7/10), while all samples were negative for T. medium. However, none of these Treponema species could be isolated and sequence analysis of the amplified products showed 100% match of 365 base pairs (bp) to Treponema phylotype PT3 and almost full match (530 of 532 bp, 99.6%) to Treponema phylotype PT13. The presence of T. phagedenis, PT3 and PT13 phylotypes was confirmed by FISH analyses. The phylotypes of T. phagedenis were present in all hybridized positive biopsies of Treponema spp., and PT13 and PT3 were less abundant. Neither D. nodosus nor F. necrophorum were detected. The histological Treponema score was mostly mild. Digital dermatitis in captive European Bison is contagious and differs from bovine digital dermatitis, concerning associated pathogens as well as gross appearance.
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Affiliation(s)
| | - Tim K. Jensen
- Center for Diagnostic, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Isabelle Brodard
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Corinne Gurtner
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Richard Eicher
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Adrian Steiner
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Peter Kuhnert
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Maher Alsaaod
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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OCCURRENCE OF FOOTROT IN FREE-RANGING ALPINE IBEX (CAPRA IBEX) COLONIES IN SWITZERLAND. J Wildl Dis 2021; 57:327-337. [PMID: 33822150 DOI: 10.7589/jwd-d-20-00050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 10/09/2020] [Indexed: 11/20/2022]
Abstract
Footrot is a worldwide economically important, debilitating disease caused by Dichelobacter nodosus. In sheep (Ovis aries), it is characterized by lesions of varying severity, depending on the strain, whereas Alpine ibex (Capra ibex) seem to develop severe lesions, whatever the strain. Healthy carriers occur in livestock but are rare in wild ruminants. Using a triangulation approach (retrospective questionnaire survey, necropsy database screening, and pathogen prevalence estimation in selected ibex colonies with and without footrot), we aimed at evaluating the importance of footrot in the ibex population, identifying potential risk factors for disease occurrence in this species, and defining the epidemiological role of ibex. Our study revealed that footrot occurs throughout the entire ibex territory (34% of the Swiss ibex colonies affected) but only as a sporadic disease (mostly one case per disease event), although the situation differed among footrot-positive colonies because half of them had experienced outbreak recurrences. Risk factor analysis for the occurrence of footrot in ibex colonies suggested an absence of an effect of meteorologic conditions, region, contacts with sheep or cattle (known to be very common healthy carriers of D. nodosus) and existing local disease control program. We found a significant effect only of contacts with sheep having footrot. Pathogen prevalence was very low in all investigated colonies. In conclusion, our results support previous data suggesting that ibex are susceptible spillover hosts, likely infected mainly by sympatric sheep displaying clinical signs.
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Zanolari P, Dürr S, Jores J, Steiner A, Kuhnert P. Ovine footrot: A review of current knowledge. Vet J 2021; 271:105647. [PMID: 33840488 DOI: 10.1016/j.tvjl.2021.105647] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 02/17/2021] [Accepted: 02/18/2021] [Indexed: 12/14/2022]
Abstract
Footrot is a contagious foot disease mainly affecting sheep. It is caused by the Gram-negative anaerobic bacterium Dichelobacter nodosus. Warm, wet environmental conditions favour development of footrot, and under perfect conditions, it takes just 2-3 weeks from infection to manifestation of clinical signs. Affected sheep show lameness of various degrees and often graze while resting on their carpi. Local clinical signs vary in severity and extent from interdigital inflammation (benign footrot) to underrunning of the complete horn shoe in advanced stages of virulent footrot. Laboratory diagnosis ideally involves collection of four-foot interdigital swab samples followed by competitive real time PCR, allowing for detection of the presence of D. nodosus and differentiation between benign and virulent strains. Laboratory-based diagnostics at the flock level based on risk-based sampling and pooling of interdigital swab samples are recommended. The list of treatment options of individual sheep includes careful removal of the loose undermined horn, local or systemic administration of antimicrobials, systemic administration of non-steroidal anti-inflammatories (NSAIDs) and disinfectant footbathing. Strategies for control at the flock level are manifold and depend on the environmental conditions and the procedures traditionally implemented by the respective country. Generally, measures consist of treatment/culling of infected sheep, vaccination and prevention of reinfection of disease-free flocks. Gaining deeper insight into the beneficial effects of NSAIDs, screening for eco-friendly footbath solutions, developing better vaccines, including the development of a robust, reproducible infection model and elucidation of protective immune responses, as well as the elaboration of effective awareness training programs for sheep farmers, are relevant research gaps.
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Affiliation(s)
- Patrik Zanolari
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Salome Dürr
- Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Jörg Jores
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Adrian Steiner
- Clinic for Ruminants, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
| | - Peter Kuhnert
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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Best N, Menéndez R, Rawlin G, Suter R, Rodoni B, Beddoe T. The Consequences of Stigma for Knowledge Production: Sheep Producers' Attitudes to Footrot Diagnostics and Control in Australia. Front Vet Sci 2020; 7:354. [PMID: 32671110 PMCID: PMC7329981 DOI: 10.3389/fvets.2020.00354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 05/21/2020] [Indexed: 11/13/2022] Open
Abstract
In Australia, there is documented confusion from producers around the clinical disease of footrot, and anecdotally, knowledge of what tools are available for the diagnosis and management of footrot. When discussing footrot with producers, the authors noted a hesitation to discuss, with denial often expressed. The disease can be debilitating, both on the sheep's welfare and the producer's well-being, as it is a very difficult disease to manage and eradicate. Gaining an understanding of producer perceptions of the disease may help ensure any future actions for management and control are in-line with those identified by producers. A combination of a web-based, and manually distributed surveys of 45 sheep producers was conducted. This included closed- and open-ended questions, multi check box, and Likert scales. Responses were quantified by descriptive statistics and a thematic analysis conducted of short answers. The results of this survey indicate satisfaction with footrot diagnostics is low, while satisfaction with control methods is high. There was also a poor general understanding of footrot as a disease, and a general distrust in peers when it comes to correct management of footrot. This research addresses a gap in the literature about how sociological conditions affect diagnosis and control of footrot disease. It provides three main recommendations-simplifying the diagnostic message, encouraging a culture of trust among sheep producers and increasing governmental support-as a way to tackle this problem.
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Affiliation(s)
- Nickala Best
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience (AgriBio), La Trobe University, Melbourne, VIC, Australia
| | - Ramón Menéndez
- Department of Management, Sport and Tourism, La Trobe University, Melbourne, VIC, Australia
| | - Grant Rawlin
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Melbourne, VIC, Australia
| | - Robert Suter
- Agriculture Services and Biosecurity Operations, Department of Economic Development, Jobs, Transport and Resources, Attwood, VIC, Australia
| | - Brendan Rodoni
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Melbourne, VIC, Australia
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience (AgriBio), La Trobe University, Melbourne, VIC, Australia
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Kraft AF, Strobel H, Hilke J, Steiner A, Kuhnert P. The prevalence of Dichelobacter nodosus in clinically footrot-free sheep flocks: a comparative field study on elimination strategies. BMC Vet Res 2020; 16:21. [PMID: 31969162 PMCID: PMC6977287 DOI: 10.1186/s12917-020-2243-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 01/15/2020] [Indexed: 11/29/2022] Open
Abstract
Background Ovine footrot caused by Dichelobacter nodosus (D nodosus) is an infectious disease affecting sheep worldwide. Switzerland plans a nationwide footrot eradication program, based on PCR-testing of interdigital swab samples. The aim of this study was to test for the presence of D nodosus in clinically footrot-free sheep flocks which had been subjected to different treatment strategies, to assess whether they were feasible for the eradication process, especially focussing on antimicrobial flock treatments. Clinical scoring and PCR-results were compared. Ten farms had used hoof bathing and hoof trimming without causing bleeding, ten had used individual treatments and flock vaccines to gain the free status and ten had become free through whole-flock systemic macrolide treatment. For every farm, three risk-based collected pool samples were analysed for the occurrence of virulent and benign D nodosus by PCR detection of aprV2/aprB2. Results Six flocks from any treatment group tested positive for aprB2 in all pools. Clinical signs were absent at the time of sampling, but some flocks had experienced non-progressive interdigital inflammation previously. Two flocks tested aprV2-positive in the high-risk pool. One of them underwent a progressive footrot outbreak shortly after sampling. Individual retesting indicated, that virulent D nodosus most likely was reintroduced by a recently purchased ram. In the second flock, a ram was tested positive and treated before clinical signs occurred. Conclusions All treatment strategies eliminated the causative agent and were found to be suitable for implementation in the PCR-based eradication process. PCR-testing proved to be more sensitive than visual scoring, as it also detected clinically healthy carriers. It will be of benefit as a diagnostic tool in elimination and surveillance programs.
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Affiliation(s)
- A F Kraft
- Department of Clinical Veterinary Medicine, Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, Bremgartenstrasse 109a, CH-3001, Bern, Switzerland. .,Schafpraxis, Am Hopfenberg 8, 89352, Stoffenried, Germany.
| | - H Strobel
- Schafpraxis, Am Hopfenberg 8, 89352, Stoffenried, Germany
| | - J Hilke
- Schafpraxis, Am Hopfenberg 8, 89352, Stoffenried, Germany
| | - A Steiner
- Department of Clinical Veterinary Medicine, Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, Bremgartenstrasse 109a, CH-3001, Bern, Switzerland
| | - P Kuhnert
- Institute of Veterinary Bacteriology, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, CH-3001, Bern, Switzerland
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Moore-Jones G, Ardüser F, Dürr S, Gobeli Brawand S, Steiner A, Zanolari P, Ryser-Degiorgis MP. Identifying maintenance hosts for infection with Dichelobacter nodosus in free-ranging wild ruminants in Switzerland: A prevalence study. PLoS One 2020; 15:e0219805. [PMID: 31917824 PMCID: PMC6952115 DOI: 10.1371/journal.pone.0219805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 12/16/2019] [Indexed: 12/14/2022] Open
Abstract
Footrot is a worldwide economically important, painful, contagious bacterial foot disease of domestic and wild ungulates caused by Dichelobacter nodosus. Benign and virulent strains have been identified in sheep presenting with mild and severe lesions, respectively. However, in Alpine ibex (Capra ibex ibex), both strains have been associated with severe lesions. Because the disease is widespread throughout sheep flocks in Switzerland, a nationwide footrot control program for sheep focusing on virulent strains shall soon be implemented. The aim of this cross-sectional study was to estimate the nationwide prevalence of both strain groups of D. nodosus in four wild indigenous ruminant species and to identify potential susceptible wildlife maintenance hosts that could be a reinfection source for domestic sheep. During two years (2017–2018), interdigital swabs of 1,821 wild indigenous ruminant species (Alpine ibex, Alpine chamois (Rupicapra rupicapra), roe deer (Capreolus capreolus), red deer (Cervus elaphus)) were analysed by Real-Time PCR. Furthermore, observed interspecies interactions were documented for each sample. Overall, we report a low prevalence of D. nodosus in all four indigenous wild ruminants, for both benign (1.97%, N = 36, of which 31 red deer) and virulent (0.05%, N = 1 ibex) strains. Footrot lesions were documented in one ibex with virulent strains, and in one ibex with benign strains. Interspecific interactions involving domestic livestock occurred mainly with cattle and sheep. In conclusion, the data suggest that wild ungulates are likely irrelevant for the maintenance and spread of D. nodosus. Furthermore, we add evidence that both D. nodosus strain types can be associated with severe disease in Alpine ibex. These data are crucial for the upcoming nationwide control program and reveal that wild ruminants should not be considered as a threat to footrot control in sheep in this context.
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Affiliation(s)
- Gaia Moore-Jones
- Centre for Fish and Wildlife Health, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Flurin Ardüser
- Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Salome Dürr
- Veterinary Public Health Institute, Vetsuisse-Faculty, University of Bern, Liebefeld, Switzerland
| | - Stefanie Gobeli Brawand
- Institute of Veterinary Bacteriology, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Adrian Steiner
- Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
| | - Patrik Zanolari
- Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, Bern, Switzerland
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12
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Best N, Rawlin G, Suter R, Rodoni B, Beddoe T. Optimization of a Loop Mediated Isothermal Amplification (LAMP) Assay for In-Field Detection of Dichelobacter nodosus With aprV2 (VDN LAMP) in Victorian Sheep Flocks. Front Vet Sci 2019; 6:67. [PMID: 30906742 PMCID: PMC6418044 DOI: 10.3389/fvets.2019.00067] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/15/2019] [Indexed: 11/21/2022] Open
Abstract
Dichelobacter nodosus is the primary etiological agent of footrot in sheep and has a variety of virulence factors. Of these, AprV2, an extracellular protease, has been shown to be capable of causing severe or “virulent” disease symptoms under the right conditions. Due to this, a loop-mediated isothermal amplification (LAMP) assay for the detection of aprV2-positive D. nodosus (VDN LAMP) was developed and evaluated for field use. A sample of 19 sheep flocks (309 sheep) in Victoria, Australia, were tested to determine the optimum conditions for in-field VDN LAMP assay use and sampling, for detecting aprV2-positive D. nodosus infected sheep. VDN LAMP performance was compared to a validated rtPCR that detects aprV2 and the benign strain counterpart, aprB2, using biologically duplicate samples to determine sensitivity and specificity. Flocks were sampled either in winter-spring (moist) or early summer (dry) conditions and had a range of clinical expressions of the disease ovine footrot. Variables considered for optimizing field performance were: sample collection method, sample preparation, clinical expression of disease, and nature of the feet when sampled (moist vs. dry, clean vs. soiled). The test was found to perform best when sheep were sampled with moist, clean feet, using a dry swab with the sample prepared in alkaline polyethylene glycol, pH 13.0, as the collection buffer. A sensitivity of 89% and specificity of 97% was seen when used in-field under these conditions, when compared to aprV2 detection by rtPCR, with “very good” agreement to rtPCR results. This study shows the VDN LAMP test is easy to use in-field to identify the presence of aprV2-positive D. nodosus in sheep flocks.
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Affiliation(s)
- Nickala Best
- Beddoe Laboratory, Department of Animal, Plant and Soil Science, La Trobe University, Melbourne, VIC, Australia
| | - Grant Rawlin
- Centre for AgriBioscience (AgriBio), Department of Economic Development, Jobs, Transport and Resources, Victorian Government, Melbourne, VIC, Australia
| | - Robert Suter
- Agriculture Services and Biosecurity Operations, Department of Economic Development, Jobs, Transport and Resources, Victorian Government, Attwood, VIC, Australia
| | - Brendan Rodoni
- Centre for AgriBioscience (AgriBio), Department of Economic Development, Jobs, Transport and Resources, Victorian Government, Melbourne, VIC, Australia
| | - Travis Beddoe
- Beddoe Laboratory, Department of Animal, Plant and Soil Science, La Trobe University, Melbourne, VIC, Australia
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Best N, Rodoni B, Rawlin G, Beddoe T. The development and deployment of a field-based loop mediated isothermal amplification assay for virulent Dichelobacter nodosus detection on Australian sheep. PLoS One 2018; 13:e0204310. [PMID: 30260992 PMCID: PMC6160043 DOI: 10.1371/journal.pone.0204310] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/05/2018] [Indexed: 11/19/2022] Open
Abstract
Dichelobacter nododus is the causative agent of footrot, a major disease of sheep that creates welfare concerns and large economic loss. The virulence of D. nododus depends on the presence of extracellular proteases, AprV2 and AprB2, which differ by one amino acid. Strains possessing AprV2 can cause clinically virulent disease, while AprB2 may cause clinically benign disease. Current methods for detecting D. nodosus are difficult, laborious and time consuming. New techniques capable of rapidly detecting and typing D. nodosus are needed to aid control programs. Molecular methods, like real-time polymerase chain reaction (rtPCR) can detect aprV2 and aprB2, however, this assay is not field-deployable and cannot support local decision-making during an outbreak. Here we present a field-based molecular assay for detecting aprV2, using loop mediated isothermal amplification (LAMP). The aprV2 LAMP (VDN LAMP) assay was optimised to reliably detect aprV2 from laboratory purified genomic (gDNA) of virulent D. nodosus down to 5x10(-3) ng μL-1, with time to positive (Tp) ≤ 16 minutes, while aprB2 was unreliably detected at 5 ng μL-1 from 16-20 minutes. The use of field collected samples that were rtPCR positive for aprB2 resulted in no amplification, while aprV2 positive field samples by VDN LAMP assay are defined as having Tps' of < 20 minutes and melting temperature between 88.0-88.9°C. When compared to rtPCR, the VDN LAMP was shown to have a diagnostic specificity of 100% and sensitivity of 83.33%. As proof of concept, the VDN LAMP was taken on farm, with all processing occurring in-field. The on farm VDN LAMP successfully detected 91.67% aprV2 positive samples, no aprB2 positive samples (n = 9) or D. nodosus negative (n = 23) samples, with a kappa agreement of 'almost perfect' to rtPCR. This highlights the potential of the assay to inform local treatment decisions for management.
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Affiliation(s)
- Nickala Best
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience (AgriBio), La Trobe University, Bundoora, Melbourne, Victoria, Australia
| | - Brendan Rodoni
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Bundoora, Melbourne, Victoria, Australia
| | - Grant Rawlin
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Bundoora, Melbourne, Victoria, Australia
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science and Centre for AgriBioscience (AgriBio), La Trobe University, Bundoora, Melbourne, Victoria, Australia
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14
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Best N, Zanandrez L, Gwozdz J, Klien E, Buller N, Suter R, Rawlin G, Beddoe T. Assessment of a rtPCR for the detection of virulent and benign Dichelobacter nodosus, the causative agent of ovine footrot, in Australia. BMC Vet Res 2018; 14:252. [PMID: 30157841 PMCID: PMC6114850 DOI: 10.1186/s12917-018-1575-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 08/16/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ovine footrot is a highly contagious bacterial disease of sheep, costing the Australian sheep industry millions of dollars annually. Dichelobacter nodosus, the causative agent of footrot, is a gram-negative anaerobe classed into virulent and benign strains as determined by thermostability of their respective protesases. Current methods for detection of D. nodosus are difficult and time-consuming, however new molecular techniques capable of rapidly detecting and typing D. nodosus have been reported. RESULTS A competitive real-time PCR (rtPCR) method, based on the ability to detect a 2 nucleotide difference in the aprV2 (virulent) and aprB2 (benign) extracellular protease gene has been tested on Australian samples for determining detection rates, along with clinically relevant cut-off values and performance in comparison to the traditional culturing methods. The rtPCR assay was found to have a specificity of 98.3% for virulent and 98.7% for benign detection from samples collected. Sheep with clinical signs of footrot showed a detection rate for virulent strains of 81.1% and for benign strains of 18.9%. A cut-off value of a Ct of 35 was found to be the most appropriate for use in Victoria for detection of sheep carrying virulent D. nodosus. CONCLUSIONS In summary, the rtPCR assay is significantly more capable of detecting D. nodosus than culturing, while there is no significant difference seen in virotyping between the two methods.
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Affiliation(s)
- Nickala Best
- Department of Animal, Plant and Soil Science, Centre for AgriBioscience (AgriBio), La Trobe University, Bundoora, Melbourne, VIC, Australia
| | - Lucas Zanandrez
- Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Jacek Gwozdz
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Bundoora, Melbourne, VIC, Australia
| | - Eckard Klien
- DAFWA Diagnostics and Laboratory Services, Biosecurity and Regulation, Department of Agriculture and Food, South Perth, Western Australia
| | - Nicky Buller
- DAFWA Diagnostics and Laboratory Services, Biosecurity and Regulation, Department of Agriculture and Food, South Perth, Western Australia
| | - Robert Suter
- Agriculture Services and Biosecurity Operations, Department of Economic Development, Jobs, Transport and Resources, Attwood, Victoria, Australia
| | - Grant Rawlin
- Department of Economic Development, Jobs, Transport and Resources Centre for AgriBioscience (AgriBio), Victorian Government, Bundoora, Melbourne, VIC, Australia
| | - Travis Beddoe
- Department of Animal, Plant and Soil Science, Centre for AgriBioscience (AgriBio), La Trobe University, Bundoora, Melbourne, VIC, Australia.
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15
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Detection and Serogrouping of Dichelobacter nodosus Infection by Use of Direct PCR from Lesion Swabs To Support Outbreak-Specific Vaccination for Virulent Footrot in Sheep. J Clin Microbiol 2018; 56:JCM.01730-17. [PMID: 29436426 DOI: 10.1128/jcm.01730-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 02/02/2018] [Indexed: 11/20/2022] Open
Abstract
Virulent footrot is an economically significant disease in most sheep-rearing countries. The disease can be controlled with vaccine targeting the fimbriae of virulent strains of the essential causative agent, Dichelobacter nodosus However, the bacterium is immunologically heterogeneous, and 10 distinct fimbrial serogroups have been identified. Ideally, in each outbreak the infecting strains would be cultured and serogrouped so that the appropriate serogroup-specific mono- or bivalent vaccine could be administered, because multivalent vaccines lack efficacy due to antigenic competition. If clinical disease expression is suspected to be incomplete, culture-based virulence tests are required to confirm the diagnosis, because control of benign footrot is economically unjustifiable. Both diagnosis and vaccination are conducted at the flock level. The aims of this study were to develop a PCR-based procedure for detecting and serogrouping D. nodosus directly from foot swabs and to determine whether this could be done accurately from the same cultured swab. A total of 269 swabs from the active margins of foot lesions of 261 sheep in 12 Merino sheep flocks in southeastern Australia were evaluated. DNA extracts taken from putative pure cultures of D. nodosus and directly from the swabs were evaluated in PCR assays for the 16S rRNA and fimA genes of D. nodosus Pure cultures were tested also by the slide agglutination test. Direct PCR using extracts from swabs was more sensitive than culture for detecting and serogrouping D. nodosus strains. Using the most sensitive sample collection method of the use of swabs in lysis buffer, D. nodosus was more likely to be detected by PCR in active than in inactive lesions, and in lesions with low levels of fecal contamination, but lesion score was not a significant factor. PCR conducted on extracts from swabs in modified Stuart's transport medium that had already been used to inoculate culture plates had lower sensitivity. Therefore, if culture is required to enable virulence tests to be conducted, it is recommended that duplicate swabs be collected from each foot lesion, one in transport medium for culture and the other in lysis buffer for PCR.
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16
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Potential transmission routes of Dichelobacter nodosus. Vet Microbiol 2018; 218:20-24. [PMID: 29685216 DOI: 10.1016/j.vetmic.2018.03.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 03/16/2018] [Accepted: 03/17/2018] [Indexed: 12/18/2022]
Abstract
Footrot caused by Dichelobacter nodosus is a highly contagious bacterial disease affecting the claw of sheep and the main cause of lameness in these animals. It is not only an economic burden but also a serious animal welfare issue. More information about the transmission of D. nodosus is needed for effective footrot control programs. We therefore determined the prevalence of D. nodosus in sheep presented at shows and markets where commingling of animals occurs. Furthermore, possible transmission vectors during foot trimming were investigated and trimming knife decontamination protocols evaluated. Sheep at six markets and four shows were sampled and tested for the presence of D. nodosus by real-time PCR. Different vectors, such as trimming knives were tested by real-time PCR and for viable D. nodosus by culture. The prevalence of virulent D. nodosus in sheep presented at shows and markets ranged from 1.7% to 100%. Regions with an ongoing control program showed significantly lower prevalence. After trimming, positive real-time PCR and culture results were obtained from the knives, the hands of the claw trimmers as well as removed claw horn material whereas boots were only positive by real-time PCR. In conclusion, markets and shows pose a risk for transmission of D. nodosus. The risk of transmission is particularly high during claw trimming and recommended measures to limit this risk include wiping the knife with a disinfection towel, wearing and changing gloves after every sheep, as well as proper disposal of trimmed and infectious horn.
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Greber D, Locher I, Kuhnert P, Butty MA, Holdener K, Frey J, Schüpbach-Regula G, Steiner A. Pooling of interdigital swab samples for PCR detection of virulent Dichelobacter nodosus. J Vet Diagn Invest 2017; 30:205-210. [PMID: 29105601 DOI: 10.1177/1040638717733508] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Virulent ovine foot rot is a contagious foot disease. Given the development and validation of a real-time PCR to detect Dichelobacter nodosus isolates that contain the virulence-associated protease genes aprV2 and aprB2, the diagnosis of foot rot has made considerable progress. We evaluated pooling methods to reduce the number of samples during a foot rot control program. Samples of individual feet were compared to a 4-feet sample of the same sheep. All further analyses based on 4-feet samples (pools-of-5 and pools-of-10 4-feet samples) were compared to samples of individual sheep, and a risk-based herd sampling was evaluated and compared to the whole flock. The sensitivity and specificity of the 4-feet samples for detection of aprV2-positive strains was 93.8% (CI: 87.6-97.5%) and 98.3% (CI: 96.5-99.3%), respectively. The sensitivity and specificity of the pools-of-10 was 86.7% (CI: 78.4-92.7%) and 100.0% (CI: 97.4-100%), respectively. Pools-of-5 were not significantly more sensitive than pools-of-10. The pooling of 4 individual foot samples into one 4-feet sample is an adequate method to reduce the number of samples of individual sheep. The sensitivity of pools-of-5 and pools-of-10 is too imprecise for a control program. Risk-based sampling allowed for a substantial reduction of samples to be tested, had a sensitivity of 95.8% (CI: 78.9-99.9%) and specificity of 100.0% (CI: 88.1-100.0%) when determining the foot rot flock status, and represents an adequate methodology to predict within-flock freedom from infection.
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Affiliation(s)
- Deborah Greber
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Iwan Locher
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Peter Kuhnert
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Marc-André Butty
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Kerstin Holdener
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Joachim Frey
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Gertraud Schüpbach-Regula
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
| | - Adrian Steiner
- Clinic for Ruminants (Greber, Locher, Butty, Steiner), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Institute of Veterinary Bacteriology (Kuhnert, Frey), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Public Health Institute (Schüpbach-Regula), Vetsuisse-Faculty Bern, University of Bern, Bern, Switzerland
- Veterinary Office of the Canton of Grisons, Chur, Switzerland (Holdener)
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18
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Maboni G, Davenport R, Sessford K, Baiker K, Jensen TK, Blanchard AM, Wattegedera S, Entrican G, Tötemeyer S. A Novel 3D Skin Explant Model to Study Anaerobic Bacterial Infection. Front Cell Infect Microbiol 2017; 7:404. [PMID: 28959685 PMCID: PMC5604072 DOI: 10.3389/fcimb.2017.00404] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/31/2017] [Indexed: 12/11/2022] Open
Abstract
Skin infection studies are often limited by financial and ethical constraints, and alternatives, such as monolayer cell culture, do not reflect many cellular processes limiting their application. For a more functional replacement, 3D skin culture models offer many advantages such as the maintenance of the tissue structure and the cell types present in the host environment. A 3D skin culture model can be set up using tissues acquired from surgical procedures or post slaughter, making it a cost effective and attractive alternative to animal experimentation. The majority of 3D culture models have been established for aerobic pathogens, but currently there are no models for anaerobic skin infections. Footrot is an anaerobic bacterial infection which affects the ovine interdigital skin causing a substantial animal welfare and financial impact worldwide. Dichelobacter nodosus is a Gram-negative anaerobic bacterium and the causative agent of footrot. The mechanism of infection and host immune response to D. nodosus is poorly understood. Here we present a novel 3D skin ex vivo model to study anaerobic bacterial infections using ovine skin explants infected with D. nodosus. Our results demonstrate that D. nodosus can invade the skin explant, and that altered expression of key inflammatory markers could be quantified in the culture media. The viability of explants was assessed by tissue integrity (histopathological features) and cell death (DNA fragmentation) over 76 h showing the model was stable for 28 h. D. nodosus was quantified in all infected skin explants by qPCR and the bacterium was visualized invading the epidermis by Fluorescent in situ Hybridization. Measurement of pro-inflammatory cytokines/chemokines in the culture media revealed that the explants released IL1β in response to bacteria. In contrast, levels of CXCL8 production were no different to mock-infected explants. The 3D skin model realistically simulates the interdigital skin and has demonstrated that D. nodosus invades the skin and triggered an early cellular inflammatory response to this bacterium. This novel model is the first of its kind for investigating an anaerobic bacterial infection.
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Affiliation(s)
- Grazieli Maboni
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
| | - Rebecca Davenport
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
| | - Kate Sessford
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
| | - Kerstin Baiker
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
| | - Tim K. Jensen
- National Veterinary Institute, Technical University of DenmarkCopenhagen, Denmark
| | - Adam M. Blanchard
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
| | | | | | - Sabine Tötemeyer
- School of Veterinary Medicine and Science, University of NottinghamNottingham, United Kingdom
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19
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Smith EM, Gilbert A, Russell CL, Purdy KJ, Medley GF, Muzafar M, Grogono-Thomas R, Green LE. Within-Flock Population Dynamics of Dichelobacter nodosus. Front Vet Sci 2017; 4:58. [PMID: 28484704 PMCID: PMC5401886 DOI: 10.3389/fvets.2017.00058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/05/2017] [Indexed: 11/13/2022] Open
Abstract
Footrot causes 70-90% of lameness in sheep in Great Britain. With approximately 5% of 18 million adult sheep lame at any one time, it costs the UK sheep industry £24-84 million per year. The Gram-negative anaerobe Dichelobacter nodosus is the causative agent, with disease severity influenced by bacterial load, virulence, and climate. The aim of the current study was to characterize strains of D. nodosus isolated by culture of swabs from healthy and diseased feet of 99 ewes kept as a closed flock over a 10-month period and investigate persistence and transmission of strains within feet, sheep, and the flock. Overall 268 isolates were characterized into strains by serogroup, proline-glycine repeat (pgr) status, and multi-locus variable number tandem repeat analysis (MLVA). The culture collection contained 87 unique MLVA profiles and two major MLVA complexes that persisted over time. A subset of 189 isolates tested for the virulence marker aprV2 were all positive. The two MLVA complexes (76 and 114) comprised 62 and 22 MLVA types and 237 and 28 isolates, respectively. Serogroups B, and I, and pgrB were associated with MLVA complex 76, whereas serogroups D and H were associated with MLVA complex 114. We conclude that within-flock D. nodosus evolution appeared to be driven by clonal diversification. There was no association (P > 0.05) between serogroup, pgr, or MLVA type and disease state of feet. Strains of D. nodosus clustered within sheep and were transmitted between ewes over time. D. nodosus was isolated at more than one time point from 21 feet, including 5 feet where the same strain was isolated on two occasions at an interval of 1-33 weeks. Collectively, our results indicate that D. nodosus strains persisted in the flock, spread between sheep, and possibly persisted on feet over time.
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Affiliation(s)
- Edward M Smith
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Andrew Gilbert
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Claire L Russell
- School of Veterinary Sciences, University of Bristol, Langford, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Graham F Medley
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Mohd Muzafar
- School of Life Sciences, University of Warwick, Coventry, UK
| | | | - Laura E Green
- School of Life Sciences, University of Warwick, Coventry, UK
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20
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Frosth S, König U, Nyman AK, Aspán A. Sample pooling for real-time PCR detection and virulence determination of the footrot pathogen Dichelobacter nodosus. Vet Res Commun 2017; 41:189-193. [PMID: 28343363 PMCID: PMC5547177 DOI: 10.1007/s11259-017-9686-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/15/2017] [Indexed: 10/25/2022]
Abstract
Dichelobacter nodosus is the principal cause of ovine footrot and strain virulence is an important factor in disease severity. Therefore, detection and virulence determination of D. nodosus is important for proper diagnosis of the disease. Today this is possible by real-time PCR analysis. Analysis of large numbers of samples is costly and laborious; therefore, pooling of individual samples is common in surveillance programs. However, pooling can reduce the sensitivity of the method. The aim of this study was to develop a pooling method for real-time PCR analysis that would allow sensitive detection and simultaneous virulence determination of D. nodosus. A total of 225 sheep from 17 flocks were sampled using ESwabs within the Swedish Footrot Control Program in 2014. Samples were first analysed individually and then in pools of five by real-time PCR assays targeting the 16S rRNA and aprV2/B2 genes of D. nodosus. Each pool consisted of four negative and one positive D. nodosus samples with varying amounts of the bacterium. In the individual analysis, 61 (27.1%) samples were positive in the 16S rRNA and the aprV2/B2 PCR assays and 164 (72.9%) samples were negative. All samples positive in the aprV2/B2 PCR-assay were of aprB2 variant. The pooled analysis showed that all 41 pools were also positive for D. nodosus 16S rRNA and the aprB2 variant. The diagnostic sensitivity for pooled and individual samples was therefore similar. Our method includes concentration of the bacteria before DNA-extraction. This may account for the maintenance of diagnostic sensitivity. Diagnostic sensitivity in the real-time PCR assays of the pooled samples were comparable to the sensitivity obtained for individually analysed samples. Even sub-clinical infections were able to be detected in the pooled PCR samples which is important for control of the disease. This method may therefore be implemented in footrot control programs where it can replace analysis of individual samples.
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Affiliation(s)
- Sara Frosth
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P. O. Box 7036, SE-750 07, Uppsala, Sweden. .,Department of Microbiology, National Veterinary Institute (SVA), SE-751 89, Uppsala, Sweden.
| | - Ulrika König
- Farm and Animal Health, Kungsängens gård, SE-753 23, Uppsala, Sweden
| | - Ann-Kristin Nyman
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute (SVA), SE-751 89, Uppsala, Sweden
| | - Anna Aspán
- Department of Microbiology, National Veterinary Institute (SVA), SE-751 89, Uppsala, Sweden
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21
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Elimination of virulent strains (aprV2) of Dichelobacter nodosus from feet of 28 Swiss sheep flocks: A proof of concept study. Vet J 2016; 216:25-32. [DOI: 10.1016/j.tvjl.2016.06.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 06/26/2016] [Accepted: 06/29/2016] [Indexed: 11/21/2022]
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Vatn S. Enhanced possibilities for eradicating virulent footrot. Vet J 2016; 217:1-2. [PMID: 27810197 DOI: 10.1016/j.tvjl.2016.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 09/08/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Synnøve Vatn
- ANIMALIA, Norwegian Meat and Poultry Research Centre, P.O. Box 396 Økern, 0513 Oslo, Norway.
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Frosth S, König U, Nyman AK, Pringle M, Aspán A. Characterisation of Dichelobacter nodosus and detection of Fusobacterium necrophorum and Treponema spp. in sheep with different clinical manifestations of footrot. Vet Microbiol 2015; 179:82-90. [PMID: 25796133 DOI: 10.1016/j.vetmic.2015.02.034] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 10/23/2022]
Abstract
The aim of this study was to determine the proportion of Dichelobacter nodosus, Fusobacterium necrophorum and Treponema spp. in sheep with different clinical manifestations of footrot compared to healthy sheep both at flock and individual level. The second aim was to characterise D. nodosus with respect to virulence, presence of intA gene and the serogroups. Swab samples (n=1000) from footrot-affected (n=10) and healthy flocks (n=10) were analysed for the presence of D. nodosus, F. necrophorum and Treponema spp. by real-time PCR and culturing (D. nodosus only). Dichelobacter nodosus isolates (n=78) and positive swabs (n=474) were analysed by real-time PCR for the aprV2/B2 and the intA genes and by PCR for the fimA gene (isolates only). D. nodosus was more commonly found in flocks affected with footrot than in clinically healthy flocks. A significant association was found between feet with severe footrot lesions and the aprV2 gene and between feet with moderate or no lesions and the aprB2 gene, respectively. F. necrophorum was more commonly found in flocks with footrot lesions than in flocks without lesions. No significant association was found between sheep flocks affected with footrot and findings of Treponema spp. or the intA gene. Benign D. nodosus of six different serogroups was detected in twelve flocks and virulent D. nodosus of serogroup G in one. In conclusion, D. nodosus and F. necrophorum were more commonly found in feet with footrot than in healthy feet. The majority of D. nodosus detected was benign, while virulent D. nodosus was only detected in a single flock.
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Affiliation(s)
- Sara Frosth
- Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, P.O. Box 7028, SE-750 07 Uppsala, Sweden; Department of Bacteriology, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden.
| | - Ulrika König
- Swedish Animal Health Service, Kungsängens gård, SE-753 23 Uppsala, Sweden.
| | - Ann-Kristin Nyman
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden.
| | - Märit Pringle
- Department of Animal Health and Antimicrobial Strategies, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden.
| | - Anna Aspán
- Department of Bacteriology, National Veterinary Institute (SVA), SE-751 89 Uppsala, Sweden.
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26
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First study of pathogen load and localisation of ovine footrot using fluorescence in situ hybridisation (FISH). Vet Microbiol 2015; 176:321-7. [PMID: 25742734 PMCID: PMC4366039 DOI: 10.1016/j.vetmic.2015.01.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Revised: 01/26/2015] [Accepted: 01/29/2015] [Indexed: 01/19/2023]
Abstract
Analysis of bacterial populations in situ provides insights into pathogen population dynamics and potential reservoirs for disease. Here we report a culture-independent study of ovine footrot (FR); a debilitating bacterial disease that has significant economic impact on sheep farming worldwide. Disease begins as an interdigital dermatitis (ID), which may then progress to separation of the hoof horn from the underlying epidermis causing severe footrot (SFR). Dichelobacter nodosus is the causative agent of ovine FR, however, the role of Fusobacterium necrophorum and other bacteria present in the environment and on the feet of sheep is less clear. The objective of this study was to use fluorescence in situ hybridisation (FISH) to detect, localise and quantify D. nodosus, F. necrophorum and the domain Bacteria from interdigital skin biopsies of healthy, ID- and SFR-affected feet. D. nodosus and F. necrophorum populations were restricted primarily to the epidermis, but both were detected more frequently in feet with ID or SFR than in healthy feet. D. nodosus cell counts were significantly higher in feet with ID and SFR (p<0.05) than healthy feet, whereas F. necrophorum cell counts were significantly higher only in feet with SFR (p<0.05) than healthy feet. These results, together with other published data, indicate that D. nodosus likely drives pathogenesis of footrot from initiation of ID to SFR; with D. nodosus cell counts increasing prior to onset of ID and SFR. In contrast, F. necrophorum cell counts increase after SFR onset, which may suggest an accessory role in disease pathogenesis, possibly contributing to the severity and duration of SFR.
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Pyogranulomatous pneumonia in goats caused by an undescribed Porphyromonas species, "Porphyromonas katsikii". J Clin Microbiol 2014; 53:795-8. [PMID: 25540395 DOI: 10.1128/jcm.02682-14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A yet-undescribed bacterial species, tentatively named "Porphyromonas katsikii," was isolated from individuals of a small goat herd with pyogranulomatous pneumonia during an outbreak of acute respiratory disease. The isolated bacteria grew in the form of black-pigmented colonies after 14 days of incubation under anaerobic conditions at 37°C on a tryptic soy blood agar medium. The bacteria were identified as a yet-undescribed Porphyromonas species by determination of the nucleotide sequence of the rrs 16S rRNA gene, and this species was tentatively named Porphyromonas katsikii. PCR amplification with specific primers for this yet-undescribed species revealed the presence of P. katsikii in the lung tissue of all affected animals, while no PCR signals were evidenced from the lungs of healthy goats or from goats with pasteurellosis caused by Mannheimia haemolytica. These data indicate P. katsikii as the causative agent of acute respiratory distress. P. katsikii is phylogenetically related to Porphyromonas somerae and Porphyromonas levii, which cause pathologies in humans and animals, respectively. P. katsikii was not detected by PCR from samples of the gingival pockets or of the faces of healthy goats.
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Genomic evidence for a globally distributed, bimodal population in the ovine footrot pathogen Dichelobacter nodosus. mBio 2014; 5:e01821-14. [PMID: 25271288 PMCID: PMC4196234 DOI: 10.1128/mbio.01821-14] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Footrot is a contagious, debilitating disease of sheep, causing major economic losses in most sheep-producing countries. The causative agent is the Gram-negative anaerobe Dichelobacter nodosus. Depending on the virulence of the infective bacterial strain, clinical signs vary from a mild interdigital dermatitis (benign footrot) to severe underrunning of the horn of the hoof (virulent footrot). The aim of this study was to investigate the genetic relationship between D. nodosus strains of different phenotypic virulences and between isolates from different geographic regions. Genome sequencing was performed on 103 D. nodosus isolates from eight different countries. Comparison of these genome sequences revealed that they were highly conserved, with >95% sequence identity. However, single nucleotide polymorphism analysis of the 31,627 nucleotides that were found to differ in one or more of the 103 sequenced isolates divided them into two distinct clades. Remarkably, this division correlated with known virulent and benign phenotypes, as well as with the single amino acid difference between the AprV2 and AprB2 proteases, which are produced by virulent and benign strains, respectively. This division was irrespective of the geographic origin of the isolates. However, within one of these clades, isolates from different geographic regions generally belonged to separate clusters. In summary, we have shown that D. nodosus has a bimodal population structure that is globally conserved and provide evidence that virulent and benign isolates represent two distinct forms of D. nodosus strains. These data have the potential to improve the diagnosis and targeted control of this economically significant disease. The Gram-negative anaerobic bacterium Dichelobacter nodosus is the causative agent of ovine footrot, a disease of major importance to the worldwide sheep industry. The known D. nodosus virulence factors are its type IV fimbriae and extracellular serine proteases. D. nodosus strains are designated virulent or benign based on the type of disease caused under optimal climatic conditions. These isolates have similar fimbriae but distinct extracellular proteases. To determine the relationship between virulent and benign isolates and the relationship of isolates from different geographical regions, a genomic study that involved the sequencing and subsequent analysis of 103 D. nodosus isolates was undertaken. The results showed that D. nodosus isolates are highly conserved at the genomic level but that they can be divided into two distinct clades that correlate with their disease phenotypes and with a single amino acid substitution in one of the extracellular proteases.
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Simultaneous detection and discrimination of virulent and benign Dichelobacter nodosus in sheep of flocks affected by foot rot and in clinically healthy flocks by competitive real-time PCR. J Clin Microbiol 2014; 52:1228-31. [PMID: 24452162 DOI: 10.1128/jcm.03485-13] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ovine foot rot caused by Dichelobacter nodosus is affecting sheep worldwide. The current diagnostic methods are difficult and cumbersome. Here, we present a competitive real-time PCR based on allelic discrimination of the protease genes aprV2 and aprB2. This method allows direct detection and differentiation of virulent and benign D. nodosus from interdigital skin swabs in a single test. Clinically affected sheep harbored high loads of only virulent strains, whereas healthy sheep had lower loads of predominantly benign strains.
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