View source for Biology:Dichelobacter nodosus

{{Short description|Species of bacterium}}
{{Italic title}}
{{Taxobox
| name = ''Dichelobacter nodosus''
| domain = [[Biology:Bacteria|Bacteria]]
| phylum = [[Biology:Pseudomonadota|Pseudomonadota]]
| classis = [[Biology:Gammaproteobacteria|Gammaproteobacteria]]
| ordo = Cardiobacteriales
| familia = [[Biology:Cardiobacteriaceae|Cardiobacteriaceae]]
| genus = '''''Dichelobacter'''''
| species = '''''D. nodosus'''''
| binomial = ''Dichelobacter nodosus''
| binomial_authority = (Beveridge 1941)<br>(Mraz 1963)<br>Dewhirst ''et al.'' 1990 
}}

'''''Dichelobacter nodosus''''', formerly ''Bacteroides nodosus'', is a Gram-negative, obligate anaerobe of the family Cardiobacteriaceae. It has polar [[Biology:Fimbria (bacteriology)|fimbriae]] and is the causative agent of ovine [[Biology:Foot rot|foot rot]] as well as [[Biology:Interdigital dermatitis in cattle|interdigital dermatitis]].<ref name=Merck>{{cite web|url=http://www.merckvetmanual.com/mvm/musculoskeletal_system/lameness_in_cattle/interdigital_dermatitis_stable_footrot_slurry_heel_scald_in_cattle.html |access-date=26 June 2016 |title=Interdigital Dermatitis (Stable footrot, Slurry heel, Scald) in Cattle |publisher=Merck Veterinary Manual |date=September 2015}}</ref> It is the lone species in the genus '''''Dichelobacter'''''.

''Dichelobacter nodosus'', formerly ''Bacteroides nodosus'', is a gram negative, rod shaped, obligate anaerobe of the family Cardiobacteriaceae. It has polar fimbriae epitomes that separate the bacteria into multiple serogroups.<ref name="McPherson_2018">{{cite journal | vauthors = McPherson AS, Dhungyel OP, Whittington RJ | title = 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 | journal = Journal of Clinical Microbiology | volume = 56 | issue = 4 | pages = e01730–17 | date = April 2018 | pmid = 29436426 | doi = 10.1128/jcm.01730-17 | pmc = 5869834 }}</ref>

''D. nodosus,'' along with ''Fusobacterium necrophorum,'' co-exist as the causative agents of ovine foot rot and interdigital dermatitis in ungulates globally, especially in temperate zones.<ref name="Kraft_2020">{{cite journal | vauthors = Kraft AF, Strobel H, Hilke J, Steiner A, Kuhnert P | title = The prevalence of Dichelobacter nodosus in clinically footrot-free sheep flocks: a comparative field study on elimination strategies | journal = BMC Veterinary Research | volume = 16 | issue = 1 | pages = 21 | date = January 2020 | pmid = 31969162 | pmc = 6977287 | doi = 10.1186/s12917-020-2243-8 | doi-access = free }}</ref><ref name="ANZSDP-Ovine-footrot">{{cite web | date=2020|title=ANZSDP-Ovine-footrot.pdf|url=https://www.agriculture.gov.au/search?search_api_fulltext=ovine%20footrot&f%5B0%5D=taxonomy_content_type_media%3A840|website=Australian Government}}</ref><ref name="Pessanit_2009" /> Clinical signs can vary into two categories; virulent and benign, with the distinction between the two varying dependent on location.<ref name="MMV_Footrot">{{cite web|title=Contagious Footrot in Sheep - Musculoskeletal System|url=https://www.merckvetmanual.com/musculoskeletal-system/lameness-in-sheep/contagious-footrot-in-sheep|access-date=2020-11-07|website=Merck Veterinary Manual|language=en-US}}</ref><ref name="Buller_2014">{{cite web| vauthors = Buller N, Eamens G |date=May 2014|title=Ovine Footrot|url=https://www.agriculture.gov.au/sites/default/files/sitecollectiondocuments/animal/ahl/ANZSDP-Ovine-footrot.pdf|access-date=October 4, 2020|website=Australian Government - The Department of Agriculture, Water, and the Environment}}</ref>

Treatment options include footbaths, parenteral administration of long-acting antimicrobials, concurrent use of vaccines, and removal of affected sheep into a clean, quarantined area.<ref name="MMV_Footrot" /><ref name="Kraft_2020" /><ref name="Dhungyel_2014">{{cite journal | vauthors = Dhungyel O, Hunter J, Whittington R | title = Footrot vaccines and vaccination | journal = Vaccine | volume = 32 | issue = 26 | pages = 3139–46 | date = May 2014 | pmid = 24736003 | doi = 10.1016/j.vaccine.2014.04.006 }}</ref><ref name="Scott_2012">{{cite journal|vauthors = Scott P |date= May 2012 |title=Ovine footrot |journal=Livestock|language=en|volume=17|issue=3|pages=37–40|doi=10.1111/j.2044-3870.2012.00114.x}}</ref><ref name="Caetano_2018">{{cite journal | vauthors = Caetano P, Bettencourt EV, Branco S | title = Reviewing footrot in sheep. | journal = Journal of Veterinary Science & Animal Husbandry | date = 2018 | volume = 6 | issue = 4 | pages = 405–13 | url = https://core.ac.uk/download/pdf/185616667.pdf }}</ref>  Environmental management and treatment of infected is required to prevent further bacterial spread.<ref name="MMV_Footrot" />

== Cellular morphology and biochemistry ==
''D. nodosus'' is a rod shaped, gram negative, anaerobic obligate bacteria found on hooves which causes ovine foot rot. This bacterium causes the hoof to separate from underlying tissues through the production of proteases and keratinases.<ref name="Bennett_2009">{{cite journal | vauthors = Bennett G, Hickford J, Sedcole R, Zhou H | title = Dichelobacter nodosus, Fusobacterium necrophorum and the epidemiology of footrot | journal = Anaerobe | volume = 15 | issue = 4 | pages = 173–6 | date = August 2009 | pmid = 19239925 | doi = 10.1016/j.anaerobe.2009.02.002 }}</ref><ref>{{cite journal | vauthors = Kennan RM, Wong W, Dhungyel OP, Han X, Wong D, Parker D, Rosado CJ, Law RH, McGowan S, Reeve SB, Levina V, Powers GA, Pike RN, Bottomley SP, Smith AI, Marsh I, Whittington RJ, Whisstock JC, Porter CJ, Rood JI | display-authors = 6 | title = The subtilisin-like protease AprV2 is required for virulence and uses a novel disulphide-tethered exosite to bind substrates | journal = PLOS Pathogens | volume = 6 | issue = 11 | pages = e1001210 | date = November 2010 | pmid = 21124876 | doi = 10.1371/journal.ppat.1001210 | pmc = 2991261 | doi-access = free }}</ref> Its preferred environments are warm (greater than 10 degrees Celsius) and moist climates.<ref>{{cite journal | vauthors = McPherson AS, Dhungyel OP, Whittington RJ | title = Evaluation of Genotypic and Phenotypic Protease Virulence Tests for Dichelobacter nodosus Infection in Sheep | journal = Journal of Clinical Microbiology | volume = 55 | issue = 5 | pages = 1313–1326 | date = May 2017 | pmid = 28202796 | doi = 10.1128/jcm.02403-16 | pmc = 5405250 }}</ref>

''D. nodosus'' has a primary surface (K) antigen, causing the bacteria to be [[Biology:Immunogenicity|immunogenic]].<ref name="McPherson_2018" /> This bacteria has [[Biology:Synergy|synergistic]] effects with ''F. necrophorum''.<ref name="Bennett_2009" />

There are 10 serogroups that isolates are separated into based on the epitopes of the bacteria's fimbriae.<ref name="McPherson_2018" /> Class I contains serogroups A-C, E-G, I, and M ,while Class II contains serogroups D and H.<ref name="McPherson_2018" /> The serotypes are classified on the results of a slide [[Medicine:Agglutination|agglutination]] test.<ref name="McPherson_2018" />

Virulence of the bacteria vary depending on which strains of ''D. nodosus'' is present in the host population.<ref name="McPherson_2018" /> Strains that possess protease ''AprV2'' show a more severe form of foot rot that those of strains with ''AprB2'' proteases.<ref name="pmid29685216">{{cite journal | vauthors = Locher I, Giger L, Frosth S, Kuhnert P, Steiner A | title = Potential transmission routes of Dichelobacter nodosus | journal = Veterinary Microbiology | volume = 218 | pages = 20–24 | date = May 2018 | pmid = 29685216 | doi = 10.1016/j.vetmic.2018.03.024 }}</ref>

== Taxonomy and identification ==
''D. nodosus'' is in the order ''Cardiobacteriales''.<ref>{{cite journal | vauthors = Almagro G, Viale AM, Montero M, Rahimpour M, Muñoz FJ, Baroja-Fernández E, Bahaji A, Zúñiga M, González-Candelas F, Pozueta-Romero J | display-authors = 6 | title = Comparative genomic and phylogenetic analyses of Gammaproteobacterial glg genes traced the origin of the Escherichia coli glycogen glgBXCAP operon to the last common ancestor of the sister orders Enterobacteriales and Pasteurellales | journal = PLOS ONE | volume = 10 | issue = 1 | pages = e0115516 | date = 2015-01-21 | pmid = 25607991 | doi = 10.1371/journal.pone.0115516 | pmc = 4301808 | bibcode = 2015PLoSO..1015516A | doi-access = free }}</ref>

Identification of this bacteria is achieved by swabbing an infected animals foot, and isolating ''D. nodosus'' DNA from the swab.<ref name="Witzany_2011">{{cite journal|date=2011| veditors = Witzany G |title=Biocommunication in Soil Microorganisms |journal=Soil Biology| volume = 23 |doi=10.1007/978-3-642-14512-4| isbn = 978-3-642-14511-7 | s2cid = 82969072 |issn=1613-3382}}</ref> The isolated DNA then undergoes [[Biology:Polymerase chain reaction|PCR]] amplification where 16S rRNA, ''pnpA'', ''rpoD'', and ''aprV2'' and ''aprB2'' genes are isolated.<ref name="Witzany_2011" /><ref name="Pessanit_2009">{{cite report | vauthors = Pessanit L, Neary M, Hutchens T | title = Footrot in Sheep and Goats. Animal Sciences | publisher = Purdue Extension. AS-596-W. | date = September 2009 }}</ref> The validity of these results vary as there is no evidence of direct PCR-based serogrouping methods that have been proven against a reference.<ref name="Pessanit_2009" />

== Epidemiology ==
Foot rot is one of the top five globally important diseases acquired by sheep.<ref name="Clifton_2019">{{cite journal | vauthors = Clifton R, Giebel K, Liu NL, Purdy KJ, Green LE | title = Sites of persistence of Fusobacterium necrophorum and Dichelobacter nodosus: a paradigm shift in understanding the epidemiology of footrot in sheep | journal = Scientific Reports | volume = 9 | issue = 1 | pages = 14429 | date = October 2019 | pmid = 31594981 | pmc = 6783547 | doi = 10.1038/s41598-019-50822-9 | bibcode = 2019NatSR...914429C }}</ref> The primary [[Biology:Obligate|obligate]] agent for causing disease is ''D. nodosus,'' although ''[[Biology:Fusobacterium necrophorum|F. necrophorum]]'' has been reported as having synergistic effects in severe cases of foot rot.<ref>{{cite journal | vauthors = Witcomb LA, Green LE, Calvo-Bado LA, Russell CL, Smith EM, Grogono-Thomas R, Wellington EM | title = First study of pathogen load and localisation of ovine footrot using fluorescence in situ hybridisation (FISH) | journal = Veterinary Microbiology | volume = 176 | issue = 3–4 | pages = 321–7 | date = April 2015 | pmid = 25742734 | pmc = 4366039 | doi = 10.1016/j.vetmic.2015.01.022 }}</ref> Outbreaks have been reported in Australia, Britain, Norway, Switzerland.<ref name="Clifton_2019" /><ref>{{cite journal | vauthors = Gilhuus M, Kvitle B, L'Abée-Lund TM, Vatn S, Jørgensen HJ | title = A recently introduced Dichelobacter nodosus strain caused an outbreak of footrot in Norway | journal = Acta Veterinaria Scandinavica | volume = 56 | issue = 1 | pages = 29 | date = May 2014 | pmid = 24886510 | pmc = 4046027 | doi = 10.1186/1751-0147-56-29 | doi-access = free }}</ref><ref>{{cite journal | title = Outbreak of severe foot rot associated with benign Dichelobacter nodosus in an Alpine ibex colony in the Swiss Prealps | journal = Schweizer Archiv für Tierheilkunde | volume = 157 | issue = 5 | pages = 277–84 | date = May 2015 | pmid = 26753343 | doi = 10.17236/sat00021 | last1 = Wimmershoff | first1 = J. | last2 = Ryser-Degiorgis | first2 = M. | last3 = Marreros | first3 = N. | last4 = Frey | first4 = J. | last5 = Romanens | first5 = P. | last6 = Gendron | first6 = K. | last7 = Origgi | first7 = F. C. }}</ref>

''D. nodosus'' has a global distribution year-round with characteristic highly [[Medicine:Transmission|transmissible]] peaks occurring in temperate zones where there is adequate moisture and an ambient temperature above 10 degrees.<ref name="Kraft_2020" /><ref name="ANZSDP-Ovine-footrot" /> In cooler conditions, such as spring and autumn, higher disease prevalence can be observed in the UK and Ireland.<ref name="Clifton_2019" /> This bacterium has the ability to thrive in moist soil for up to two weeks. In the presence of optimal conditions, the bacterium can live up to 24 days in at least 5 degrees Celsius. In suboptimal conditions, animals will not demonstrate full clinical presentation and mild lesions may be confined to the [https://medical-dictionary.thefreedictionary.com/interdigital interdigital] skin. Detection of a lower [[Prevalence|prevalence]] and persistence occurs in dry warm climates compared to wet cool conditions.<ref name="ANZSDP-Ovine-footrot" />

Sheep and goats are the main species affected by the bacterium and are susceptible at all ages. Merino breeds appear to be more susceptible over British breeds of sheep. British breeds appear to carry more [https://www.dictionary.com/browse/natural-resistance natural resistance], displaying mild clinical signs of a short duration. Although, [[Earth:F1 hybrid|first cross]] offspring under the correct conditions can develop severe clinical disease. Cattle can become affected, although normally only suffer a mild form of infection. Wild [[Biology:Ungulate|ungulate]]s have been reported to carry the bacterium in Germany and Switzerland.<ref name="ANZSDP-Ovine-footrot" />

There are challenges associated with isolating ''D''. ''nodosus'' as more molecular-based studies need to be conducted to differentiate persistence in a domesticated farm environment<ref name="Clifton_2019" />[[File:Merino sheep.png|thumb|Merino Sheep which are more susceptible to foot rot.]]

== Pathogenesis ==
''D. nodosus'' along with ''[[Biology:Fusobacterium necrophorum|F. necrophorum]]'' co-exist and cause a disease known as ovine [[Biology:Foot rot|foot rot]], primarily found in sheep and goats.<ref name="Pessanit_2009" /> ''F. necrophorum'' alone causes foot scald predisposing the animal to co-infection with ''D. nodosus'' resulting in foot rot.<ref name="Pessanit_2009" /> ''D. nodosus'' can also be carried by cattle, deer and horses.<ref name="Pessanit_2009" /> ''D. nodosus'' infection has been reported in cattle but cases are commonly restricted to benign strains.<ref>{{cite book | vauthors = Plant J, Seaman J, Evers M | title = Footrot in Sheep and Goats | publisher = Department of Primary Industries. Primefact 1533 | edition = fourth | date = July 2017 }}</ref> In order for ''D. nodosus'' to cause disease the bacterium requires irritation to the interdigital space, this can be due to moisture or trauma to the area.<ref name="Pessanit_2009" />

The severity of foot rot has a wide range of disease presentation.<ref name="Pessanit_2009" /><ref name="Witzany_2011" /> depending on the strain or combination of strains present in the infected site and the [[Biology:Virulence|virulence]] of said strains.<ref name="Pessanit_2009" /> ''D. nodosus'' releases protease enzymes, it is the number of protease enzymes, type of protease enzymes and the type IV fimbriae that determine its virulence.<ref name="Pessanit_2009" /><ref>{{cite journal | vauthors = Billington SJ, Johnston JL, Rood JI | title = Virulence regions and virulence factors of the ovine footrot pathogen, Dichelobacter nodosus | journal = FEMS Microbiology Letters | volume = 145 | issue = 2 | pages = 147–56 | date = December 1996 | pmid = 8961550 | doi = 10.1111/j.1574-6968.1996.tb08570.x | doi-access = free }}</ref> The protease enzymes digest tissue between the hoof horn and flesh which causes pain for the affected animal.<ref name="Pessanit_2009" />

Foot rot can be classified into benign foot rot and virulent foot rot<ref name="Pessanit_2009" /> which contain ''aprB2'' genes that encode for thermolabile proteases and ''aprV2'' genes encoding for thermostable proteases respectively.<ref name="Stäuble_2014">{{cite journal | vauthors = Stäuble A, Steiner A, Frey J, Kuhnert P | title = 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 | journal = Journal of Clinical Microbiology | volume = 52 | issue = 4 | pages = 1228–31 | date = April 2014 | pmid = 24452162 | pmc = 3993488 | doi = 10.1128/JCM.03485-13 }}</ref> Benign foot rot is described as reddened and inflamed tissue between the toes.<ref name="Pessanit_2009" /> Virulent foot rot is when the bacteria begins to enter the hoof horn and can cause separation of the hoof horn from the hoof wall.<ref name="Pessanit_2009" /> In virulent strains the horn may completely separate from the underlying tissue, this makes the tissue susceptible to [[Medicine:Myiasis|fly strike]].<ref name="Pessanit_2009" />

== Disease ==
Clinical signs of foot rot in sheep can be divided into two categories; benign and virulent.<ref name="MMV_Footrot" /><ref name="Buller_2014" /> In Australia, the difference between benign or virulent is dependent on the causative strain of ''D. nodosus'' acquired foot rot and is associated with the degree of severity of the clinical signs.<ref name="Pugh_2012">{{cite book | vauthors = Pugh DG, Baird NN | title = Sheep & Goat Medicine-E-Book | publisher = Elsevier Health Sciences | date = May 2012 |doi=10.1016/c2009-0-60474-8 | isbn = 978-1-4377-2354-0 }}</ref><ref name="MMV_Footrot" /> It can be difficult to tell the difference between the two strains based on clinical signs, some countries, such as the USA, consider both the benign and virulent strains the same and treat according to clinical presentation.<ref name="MMV_Footrot" /> Clinical signs of benign foot rot are interdigital dermatitis and often, but not always, includes lameness of the affected foot or feet.<ref name="Stäuble_2014" /><ref name="MMV_Footrot" /><ref name="Buller_2014" /> Clinical signs of virulent foot rot begin as interdigital dermatitis but progress to necrosis, separation of the hoof wall from the underlying soft tissue and severe lameness.<ref name="MMV_Footrot" /> However, both categories of foot rot can progress from interdigital dermatitis to more severe, chronic, [[Biology:Necrosis|necrotizing]] lesions that can have a characteristic [[Biology:Putrefaction|putrid]] smell and cause significant lameness in the affected animal.<ref name="MMV_Footrot" /><ref name="Buller_2014" />

== Diagnosis ==
Use of a foot rot scoring guide to help confirm diagnosis and to determine the severity of the disease as well as level of treatment and management that will be required. Scoring is based on the severity of lesions on the interdigital dermis, the junction between the skin and the horn and the horn itself.<ref name="Buller_2014" /> Cases of benign foot rot tend to score on the lower end of the scale and virulent foot rot cases tend to score on the higher end.<ref name="Buller_2014" /><ref name="DPI">{{cite web | date=Feb 13, 2007|title=Diagnosis of Footrot|url=http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0003/180795/footrot-diagnosis-proc-2006-024.pdf|access-date=November 10, 2020|website=NSW Department of Primary Industries}}</ref> Other clinical signs may be present depending on the strain or the severity of the foot rot are loss of appetite, loss of body condition, decrease in wool production,<ref name="MMV_Footrot" /><ref name="Buller_2014" /><ref name="Pugh_2012" /> and decreased milk production.<ref name="Pugh_2012" /> Warm and wet conditions are favorable for the spread of foot rot so the presence of these conditions can also help support the diagnosis of foot rot due to d. nodosus as well as promote the spread to other animals in the herd<ref name="MMV_Footrot" /><ref name="Pugh_2012" />

While not routinely performed, laboratory diagnosis of ''D. nodosus'' can be done to determine the virulotype of the infection-causing strain by PCR, gelatin-gel, and elastase assay<ref name="Stäuble_2014" /> and can be used to confirm field diagnosis.<ref name="Buller_2014" /><ref name="DPI" /> Identification of extracellular proteases has historically been the basis for the differentiation between the two strains of ''D. nodosus''<ref name="Kennan_2011">{{cite journal | vauthors = Kennan RM, Han X, Porter CJ, Rood JI | title = The pathogenesis of ovine footrot | journal = Veterinary Microbiology | volume = 153 | issue = 1–2 | pages = 59–66 | date = November 2011 | pmid = 21596496 | doi = 10.1016/j.vetmic.2011.04.005  }}</ref> Benign strains of ''D. nodosus'' have proteases that are thermolabile and virulent strains have proteases that are thermostable and have higher elastase activity.<ref name="Kennan_2011" /><ref name="Stäuble_2014" /> Performance of laboratory testing to diagnose specific strains of ''D. nodosus'' by determining the protease thermostability and elastase activity are not routinely performed due to the difficulty of the laboratory procedures that often yield inconsistent results.<ref name="Stäuble_2014" /><ref name="Buller_2014" /><ref name="Kennan_2011" /> In addition, the time it takes to perform laboratory-based tests to determine the virulotype of ''D. nodosus'' is slow and may not be helpful to effectively treat or isolate the infected animal(s) and to prevent spread to other animals.<ref name="Stäuble_2014" />

== Treatment ==
The most effective treatment options for ''D. nodosus'' use a multimodal approach to ensure adequate treatment as well as limited subsequent spread .<ref name="MMV_Footrot" /><ref name="Kraft_2020" /><ref name="Scott_2012" /><ref name="Caetano_2018" /> This includes immediate treatment upon identification, foot-baths, [[Medicine:Route of administration|parenteral]] administration of long-acting [[Biology:Antimicrobial|antimicrobial]]s, concurrent use of vaccines, and removal of affected sheep into a clean, quarantined area.<ref name="MMV_Footrot" /><ref name="Kraft_2020" /><ref name="Dhungyel_2014" /><ref name="Scott_2012" /><ref name="Caetano_2018" />

The prognosis for foot rot is best when treated early, prior to progression of the disease; this helps guide the decision between treatment versus culling of affected animals in order to minimize economic losses.<ref name="MMV_Footrot" /><ref name="Kraft_2020" /><ref name="Caetano_2018" /><ref name="Scott_2012" /> Affected sheep should be monitored to ensure effectiveness of treatment and culled if clinical symptoms persist, as they are a source of contamination for the rest of the flock.<ref name="MMV_Footrot" /> Infected sheep should not return to general population until the infection is cleared and the environment is decontaminated to prevent reinfection or spread.<ref name="Caetano_2018" /><ref name="Scott_2012" /><ref name="MMV_Footrot" />

The use of foot bathes containing 10% zinc sulphate solutions have shown to be effective in both treatment and prevention, though use is controversial due to environmental impacts.<ref name="Kraft_2020" /><ref name="MMV_Footrot" /> Efficacy is also reduced when used in severe cases, as the solution has limited penetration,<ref name="Kraft_2020" /> in which case, parenteral administration of antimicrobials is the most effective treatment.

''D. nodosus'' has limited ability to persist in the environment, therefore quarantine of infected animals is crucial to prevent spread within a flock.<ref name="MMV_Footrot" />

Concurrent use of a vaccine can also help to limit disease and spread within a flock.<ref name="Dhungyel_2014" />

== Antibiotic resistance ==
Oxytetracycline has been the most commonly used antimicrobial for the treatment of ''D. nodosus''.<ref name="Caetano_2018" /><ref name="Scott_2012" /><ref name="Kraft_2020" /><ref name="MMV_Footrot" /> This bacterium has also shown sensitivity to tetracyclinces, macrolides, penicillin, cephalosporins, and fluoroquinolones; with recent studies advocating for the efficacy of gamythromycin as an alternative to oxytetracycline.<ref name="Caetano_2018" /> [[Biology:Antimicrobial resistance|Resistance]] has not yet been reported with regards to ''D. nodosus''.<ref name="Caetano_2018" /><ref name="Kraft_2020" /> The use of antimicrobials is limited due to [[Chemistry:Macrolide|macrolide]]s being of importance within human medicine, and withdrawal rates can impede economic returns and therefore their choice as a treatment option.<ref name="Caetano_2018" /><ref name="Kraft_2020" /> Improper use of antimicrobials can contribute to resistance, ineffective treatments, and a higher incidence of reinfection within a herd.<ref name="Kraft_2020" /> Early identification of ''D. nodosus'', as well as routine prevention will contribute to reduced reliance on antimicrobials, as well as less stress on emerging resistance, and economic losses.<ref name="Kraft_2020" />

== Prevention ==
Environmental management and treatment of infected animals is essential for preventing the spread of ''D. nodosus''.<ref name="MMV_Footrot" /> Infected animals should be removed from the flock to a clean environment in order to be treated, as the bacterium does not survive well over 3 weeks off a host.<ref name="MMV_Footrot" /><ref name="Kraft_2020" /> Treatment is most effective when the infection is caught early.<ref name="Kraft_2020" /> The bacterium persists on an untreated host as well as moist, warm environments, therefore treatment, proper drainage, ventilation, and sanitation is required to halt the life cycle<ref>{{cite web|title=Code of Practice for the Care and Handling of Sheep|url=https://www.nfacc.ca/sheep-code|access-date=2020-11-09|website=www.nfacc.ca}}</ref><ref name="MMV_Footrot" /><ref name="Kraft_2020" /> Reinfection is likely if the environment is not decontaminated as animals are susceptible as soon as the antimicrobials are no longer active.<ref name="MMV_Footrot" /><ref name="Kraft_2020" />

Once the environment is decontaminated, outbreaks can be prevented by ensuring replacement stock come from a verified source and are quarantined upon arrival until they test negative.<ref name="MMV_Footrot" /> New animals should be quarantined, and have their feet examined and trimmed before introduction to the general population and environment.<ref name="MMV_Footrot" /> Establishing routine foot bathes containing zinc, copper or [[Physics:Formaldehyde|formol]] on a weekly basis reduces the incidence of ''D. nodosus''.<ref name="Dhungyel_2014" /><ref name="Kraft_2020" /><ref name="MMV_Footrot" />

In areas with endemic reports of the disease, a vaccine protocol is also effective in reducing incidence within a flock and concurrent use with infection will aid recovery time.<ref name="Kraft_2020" /><ref name="MMV_Footrot" /><ref name="Dhungyel_2014" /> Efficacy of vaccines depends on the type used as well as the strain of ''D. nodosus'' that is present on the farm, therefore should be used in conjunction with other prevention efforts.<ref name="MMV_Footrot" /><ref name="Dhungyel_2014" />

Inherent resistance has been shown in certain breeds of sheep with altered hoof conformation, and therefore, reduced incidence can be selected for by means of selective breeding and cross-breeding.<ref name="Caetano_2018" /><ref name="Dhungyel_2014" />

==Known strains==
*''Dichelobacter nodosus'' ATCC 25549
*''Dichelobacter nodosus'' VCS1703A

== References ==
{{Reflist}}

== External links ==
* {{cite web|url=https://www.nlm.nih.gov/cgi/mesh/2007/MB_cgi?mode=&term=Dichelobacter+nodosus&field=entry#TreeB03.440.425.410.400|title=Dichelobacter nodosus|publisher=nlm.nih.gov|access-date=18 August 2016}}
* {{cite web|url=http://genamics.com/cgi-bin/genamics/genomes/genomesearch.cgi?field=ID&query=539|archive-url=https://web.archive.org/web/20061016095130/http://genamics.com/cgi-bin/genamics/genomes/genomesearch.cgi?field=ID&query=539 |archive-date=2006-10-16 |url-status=dead|title=Genome Project Information (GenomeSeek)|access-date=18 August 2016}}
* {{cite web|url=http://www.cabicompendium.org/AHPC/search_overview_results.asp?as_search=Dichelobacter+nodosus|title=Animal Health & Production Compendium|publisher=cabicompendium.org|access-date=18 August 2016}}
*[http://bacdive.dsmz.de/index.php?search=2236&submit=Search Type strain of ''Dichelobacter nodosus'' at Bac''Dive'' -  the Bacterial Diversity Metadatabase]

{{Taxonbar|from=Q3706891}}

[[Category:Gammaproteobacteria]]

{{Sourceattribution|Dichelobacter nodosus}}