Evidence of novel Treponema phylotypes implicated in contagious ovine digital dermatitis and association of treponemes with major lameness causing foot pathogens.

In this study 269 swabs collected from 254 ovine foot lesions and 15 apparently healthy ovine feet were screened by PCR for the presence of major lameness causing foot pathogens viz. Treponema species, D. nodosus, F. necrophorum and T. pyogenes with the presumption that ovine foot lesion positive for Treponema species alone or in association with other three pathogens were categorized as contagious ovine digital dermatitis (CODD). While samples positive for D. nodosus alone or its combination with F. necrophorum and T. pyogenes were considered as footrot (FR) and samples in which F. necrophorum or T. pyogenes was found either alone or in combination were considered as interdigital dermatitis (ID). The overall occurrence of Treponema sp. in ovine foot lesions was 48.0%, and ranged from 33 to 58%. In Treponema positive samples D. nodosus, F. necrophorum and T. pyogenes were present in 34 (27.4%), 66 (54.4%) and 84 (68.5%) in contrast to Treponema negative samples in which these were present in 15 (11.1%), 20 (14.12%) and 17 (12.6%) samples, respectively. The data signifies that Treponema sp. are significantly associated with these foot pathogens and their different combinations with Treponema sp. influence the severity of CODD lesion. The identification of Treponema phylotypes was done by sequencing the 16S rRNA gene fragment of ten representative samples. Out of ten sequences, four (Trep-2, Trep-4, Trep-7 and Trep-10) were identical to Treponema sp. phylotype 1 (PT1) that belongs to phylogroup T. refringens-like, one sequence (Trep-1) was genetically close (90% sequence homology) to Treponema brennaborense while five sequences (Trep-3, Trep-5, Trep-6, Trep-8 and Trep-9) matched with uncultured bacterium clones of treponemes forming separate monophyletic group in phylogenetic tree and could represent new digital dermatitis phylogroup presently containing five ovine specific phylotypes. This is the first report on the presence of Treponema phylotypes other than three digital dermatitis (DD) Treponema phylogroups viz. T. phagedenis-like, T. medium/T. vincentii-like, and T. pedis-like that are frequently detected in CODD lesions. Metagenomic analysis of two representative samples revealed the abundance of genus Treponema in CODD lesion while this genus was absent in swab collected from clinically healthy foot suggesting that it might play primary role in producing CODD. These findings may further aid in understanding the etiopathogenesis of CODD and could help to develop appropriate treatment and mitigation strategies to combat the disease.

Treponema spp. spirochetes and keratinopathogenic fungi isolated from keratomas in donkeys.

Keratoma is an aberrant keratin mass thought to originate from epidermal horn-producing cells interposed between the stratum medium of the hoof wall and the underlying third phalanx. The cause is unknown, although the presence of keratomas is frequently associated with chronic irritation, focal infection, or trauma. A total of 167 donkeys with keratomas were presented in this study. The diagnosis of a keratoma was based on clinical signs, radiography, and histopathologic examination. Surgical excision was attempted on all donkeys with lameness unless euthanasia was advised. Histopathologic examination, including Giemsa, periodic acid Schiff, and Young's silver special histochemical stains, was performed and showed the presence of fungal hyphae and spirochete bacteria within the degenerate keratin. Polymerase chain reaction (PCR) for treponeme bacteria was performed on 10 keratoma lesions and 9 healthy pieces of hoof (controls). All healthy donkey tissues were negative for the 3 recognized digital dermatitis (DD) treponeme phylogroups, whereas 3 of 10 (30%) donkey keratoma samples were positive for one of the DD treponeme phylogroups. Routine fungal culture and PCR for fungi were performed on 8 keratoma lesions and 8 healthy pieces of hoof (controls). Keratinopathogenic fungi were detected in 1 of 8 (12.5%) keratomas, while only non-keratinopathogenic, environmental fungi were detected in 8 control healthy hoof samples. This is the first time the DD treponemes phylogroup and keratinopathogenic fungi have been detected in keratomas. Further studies are required to assess the significance of this finding.

Farm-level risk factors for digital dermatitis in dairy cows in mountainous regions.

Reduction of risk factors for bovine digital dermatitis (BDD) is crucial in current disease control. However, risk factors that might arise especially in mountainous regions are unknown until now, and an adapted BDD control program is consequently missing. The objective of this observational case-control study was to identify farm-level risk factors for BDD in dairy herds in mountainous regions. To investigate predictors for the occurrence of BDD, 100 farms were visited and information about herd characteristics and management practices, potentially relevant explanatory variables for either introduction or establishment of BDD, were gathered by completing a questionnaire with the farmer or herd manager. Within-herd prevalences of BDD assessed during 3 routine claw trimmings with an interval of 6 mo before the survey were used to define cases (BDD within-herd prevalence of ≥26% during each claw trimming) and controls (no BDD cases in each of the 3 routine claw trimmings before the survey). Data were analyzed using 2 separate binomial generalized linear models according to either establishment or introduction of BDD. After prescreening, 15 of 23 explanatory variables were included in the final analysis, which showed 3 variables related to introduction and establishment, each being significantly associated with the occurrence of BDD within a farm. Results of model 1 (i.e., aspects related to BDD introduction) revealed that access to mountain pastures during the summer season (odds ratio, 95% confidence interval: 0.12, 0.04-0.35), participation in dairy shows (0.32, 0.11-0.94), and the number of new animals introduced into the farm during the last 2 yr (1.28, 1.12-1.52) were significantly associated with the occurrence of BDD. Model 2 (i.e., aspects related to BDD establishment) showed that cows kept in freestalls were at higher risk for BDD compared with those kept in tiestalls (20.65, 1.59-649.37). Furthermore, number of days between diagnosis and treatment of a BDD lesion (10.31, 3.55-81.21) and the amount of concentrate feeding (median 5 kg) per cow and day (7.72, 2.46-6.47) were positively associated with BDD occurrence. In conclusion, the findings of this study provide a set of risk factors that are associated with BDD status within herds in mountainous regions. These results may help in development of adapted control programs for BDD in dairy cows.

Investigation of possible aetiological/triggering factors in porcine ear necrosis syndrome at a farrow-to-feeder pig system.

At a commercial farrow-to-feeder pig system with 2,100 sows in Serbia, lesions resembling porcine ear necrosis syndrome were observed in 80% of the weaned pigs at 45-50 days of age. Pathomorphological examinations were carried out on 10 pigs that had been found dead. The gross lesions ranged from mild, superficial dermatitis to severe, deep inflammation with exudation, ulceration and necrosis. Histopathological examination revealed erosive and ulcerative dermatitis of the pinna with neutrophilic and lymphocytic infiltration and bacterial colonies in the crusts. Staphylococcus aureus (MRSA strain), Staphylococcus hyicus and Streptococcus group C were cultivated from eight, S. hyicus from two ear tissue scraping samples. All 10 samples were positive for treponemes and phylogenetic analysis of two polymerase chain reaction products confirmed the relationship to Treponema (T.) medium/vincentii and Treponema pedis. Treponemes were also detected in seven oral swabs that were analysed to obtain evidence of the transmission of this bacterium by ear biting. The contribution of non-infectious factors to this misbehaviour could not be ruled out as the crude protein concentration of the feed was inappropriate and the climate of the pig house was suboptimal. The concentrations of selected mycotoxins in the feed were not elevated. However, the contribution of both infectious and non-infectious factors to the onset of disease was most probable.

Removal of bovine digital dermatitis-associated treponemes from hoof knives after foot-trimming: a disinfection field study.

BACKGROUND: Bovine digital dermatitis (BDD) is an infectious foot disease found commonly in dairy herds. Foot-trimming is an important husbandry procedure for reducing the ensuing lameness; however, epidemiological, and microbiological studies have identified this as a risk activity for transmitting BDD. Three disinfectants have previously been identified in laboratory work as effective for removing viable BDD-associated Treponema spp., from hoof knife blades. The present study enrolled 133 dairy cattle with BDD lesions, and swabbed hoof knife blades before and after foot-trimming, and after knife disinfection with one of three disinfectants (1:100 FAM30®, 2% Virkon® and 2% sodium hypochlorite) to assess their efficacy under field conditions. RESULTS: Detection of BDD treponeme phylogroup DNA was undertaken by direct PCR of swabs, and viable treponemes were detected by PCR of swab cultures after 6 weeks' incubation. Where hoof knives did not contact the lesion, BDD-associated treponemes were detected after foot-trimming in 12/22 (54.5%) cases by direct PCR and 1/22 (4.5%) cases by PCR of cultured organisms. Where contact was made with the lesion, 111/111 (100%) samples taken after trimming were positive by direct PCR and 47/118 (39.8%) were positive by culture PCR. Viable organisms were identified in cultures from lesion stages M2, M3, M4 and M4.1. No viable organisms were detected after disinfection of hoof knives. CONCLUSIONS: Hoof knives post-trimming were frequently contaminated with BDD-associated treponeme DNA. Viable organisms were identified in cultures whether contact had been made between hoof knife and lesion or not, although contact clearly increased the frequency of detection of viable organisms. The three disinfectants tested were effective for removing viable organisms. The disinfection protocol used in this study should therefore be considered reliable for adoption as standard industry practice.

Multilocus Sequence Typing of Treponema pallidum subsp. pallidum in Cuba From 2012 to 2017.

BACKGROUND: The increased prevalence of syphilis in Cuba prompted us to map the circulating Treponema pallidum subsp. pallidum allelic profiles in this geographic region. METHODS: Samples were collected from 2012 to 2017, from 83 male patients with ulcers or skin lesions, and were examined using multilocus sequence typing. Additionally, we analyzed the 23S rDNA and 16S rDNA regions for the presence of possible mutations leading to macrolide and tetracycline resistance. RESULTS: Among 94% of fully typed strains, we found 7 different allelic profiles, of which 4 had not been previously described. More than 87% of patients were infected with the T. pallidum SS14-like group and only 8.2% with T. pallidum Nichols-like group. As in other countries, the 1.3.1 allelic profile (ie, SS14-like) was the most common. In addition, 1 of the newly described allelic profiles represents T. pallidum strains that arose by recombination events between members of different T. pallidum subgroups. More than 90% of patients were infected with treponemes harboring the A2058G mutation. However, we found no potential tetracycline-resistant T. pallidum mutations. CONCLUSIONS: Our results suggest that, in Cuba, tetracycline antibiotics could be used to treat syphilis in penicillin-allergic patients instead of macrolides.

Molecular Screening for Digital Dermatitis-Associated Treponemes in Bovine Ischaemic Teat Necrosis Lesions and Milk in Dairy Cattle.

Bovine ischaemic teat necrosis (ITN) is a disease affecting the skin of the teats of dairy cows with an unknown aetiopathogenesis. Digital dermatitis (DD)-associated treponemes have previously been suggested as a potential aetiological agent in ITN, although the sample size was small. The current study, using established PCR techniques, aimed to examine the association with the presence of DD-associated treponemes in a large number of ITN samples from a wider geographical area, and surveyed the potential of milk as an infection reservoir. From 95 ITN lesions, 35.8% (n = 34) were positive for at least one DD-associated treponeme compared with only 5.6% (n = 1) of 18 non-lesioned teats from cows with ITN lesions on a different teat using a nested PCR approach. All 10 age- and production-matched control cows were negative for DD-associated treponemes via PCR. No DD-associated treponemes could be detected from foremilk of cows with (n = 19) and without (n = 31) a DD lesion on the hind feet. DD-associated treponemes could be detected via PCR after incubation in milk for up to 2 h. Therefore, milk does not appear to be a competent reservoir for transmission of DD-associated treponemes. Moreover, in the current study DD-associated treponemes were only detected in a subset of ITN samples, so it is unlikely these opportunistic skin-associated pathogens are the major or sole agent of ITN.

Treponemes-infected canker in a Japanese racehorse: efficacy of maggot debridement therapy.

A 3-year-old thoroughbred colt presented with canker on its left hind foot. Subsequent development of cottage cheese-like horns and dermatitis disturbed healing, despite the use of miscellaneous orthodox treatment approaches to the lesions. Histological examination revealed exudative and suppurative dermatitis, and proliferatively suppurative epidermitis infected with helically coiled treponemes. Total debridement under general anesthesia led to a temporary improvement, but the ground surface regenerated abnormal epidermis similar to that observed initially after surgery. Maggot debridement therapy (MDT) was attempted, which removed all the abnormal tissue. After MDT, general farriery trimming helped to correct the distorted ground surface, and the horse returned to constant training and eventually raced. This case shows that MDT was successfully used for treatment of an intractable and treponemes-infected canker.

"Non-healing" claw horn lesions in dairy cows: Clinical, histopathological and molecular biological characterization of four cases.

The increasing prevalence of bovine digital dermatitis (BDD) contributes to a higher occurrence of secondary infections of exposed corium with Treponema spp. in bovine claws. "Non-healing" claw horn lesions (NHL) clinically resemble BDD lesions. They are severe, cause chronic lameness, and may persist for several months. They poorly respond to standard treatments of BDD and represent a serious welfare issue. In this study, four cases of NHL were classified clinically either as BDD-associated axial horn fissures (BDD-HFA; n = 3) or BDD-associated sole ulcer (BDD-SU; n = 1). In all four cases, pronounced multifocal keratinolysis of the stratum corneum, ulceration, and severe chronic lymphoplasmacytic perivascular to interstitial dermatitis were observed. All lesional samples tested positive for Treponema spp., Fusobacterium (F.) necrophorum, and Porphyromonas (P.) levii by PCRs. BDD-HFA lesions contained Treponema pedis as revealed by genetic identities of 93, 99, and 100%. Treponemes in the BDD-SU lesion were 94% homologous to Treponema phylotype PT3. Fluorescent in situ hybridization (FISH) revealed extensive epidermal infiltration by treponemes that made up > 90% of the total bacterial population in all four lesions. FISH also tested positive for P. levii and negative for F. necrophorum in all four cases, whilst only one BDD-HFA contained Dichelobacter nodosus. Our data point to BDD-associated treponemes and P. levii constituting potential etiological agents in the development of "non-healing" claw horn lesions in cattle.

Survival of bovine digital dermatitis treponemes on hoof knife blades and the effects of various disinfectants.

BACKGROUND: Bovine digital dermatitis (BDD) is a painful infectious foot disease of cattle, and much evidence implicates a pathogenic role for treponemes. This study measured the survival of BDD treponemes on hoof knife blades and tested the efficacy of relevant disinfectants under laboratory conditions. METHODS: Two strains of BDD treponemes were applied to hoof knife blades under aerobic conditions. Swabs were taken at different time points (10 minutes, one hour, two hours, four hours and 18 hours) and again after 20-second disinfection time with one of five disinfectants. Swabs were used directly for nested PCR to detect treponemes or inoculated for anaerobic growth, and subsequently examined using phase contrast microscopy and PCR. RESULTS: BDD treponeme DNA was detectable by nested PCR at all survival time points, and these organisms were culturable from hoof knives for two hours after exposure under aerobic conditions in the laboratory. Three of the five disinfectants-1 per cent volume per volume (v/v) FAM30®, 2 per cent weight per volume (w/v) Virkon® or 2 per cent (v/v) sodium hypochlorite-were effective at preventing visible growth of treponemes following 20-seconds contact, and 1 per cent (v/v) FAM30® also prevented detection of treponemes by PCR. CONCLUSION: Treponeme viability of two hours under aerobic conditions suggests BDD treponemes could be transmitted between cows on hoof knives. It is therefore important to apply a disinfection protocol during foot-trimming; the authors have identified three common disinfectants that may be suitable.

Challenge of Bovine Foot Skin Fibroblasts With Digital Dermatitis Treponemes Identifies Distinct Pathogenic Mechanisms.

Bovine digital dermatitis (BDD) is a common infectious disease of digital skin in cattle and an important cause of lameness worldwide, with limited treatment options. It is of increasing global concern for both animal welfare and food security, imposing a large economic burden on cattle farming industries each year. A polytreponemal etiology has been consistently identified, with three key phylogroups implicated globally: Treponema medium, Treponema phagedenis, and Treponema pedis. Pathogenic mechanisms which might enable targeted treatment/therapeutic development are poorly defined. This study used RNA sequencing to determine global differential mRNA expression in primary bovine foot skin fibroblasts following challenge with three representative BDD treponemes and a commensal treponeme, Treponema ruminis. A pro-inflammatory response was elicited by the BDD treponemes, mediated through IL-8/IL-17 signaling. Unexpectedly, the three BDD treponemes elicited distinct mechanisms of pathogenesis. T. phagedenis and T. pedis increased abundance of mRNA transcripts associated with apoptosis, while T. medium and T. pedis increased transcripts involved in actin rearrangement and loss of cell adhesion, likely promoting tissue invasion. The upregulation of antimicrobial peptide precursor, DEFB123, by T. phagedenis spirochaetes may present a microbial ecological advantage to all treponemes within BDD infected tissue, explaining their dominance within lesions. A commensal, T. ruminis, significantly dysregulated over three times the number of host mRNA transcripts compared to BDD treponemes, implying BDD treponemes, akin to the syphilis pathogen (Treponema pallidum), have evolved as "stealth pathogens" which avoid triggering substantial host immune/inflammatory responses to enable persistence and tissue invasion. Immunohistochemistry demonstrated increased IL-6, IL-8, RND1, and CFB protein expression in BDD lesions, confirming in vitro fibroblast observations and highlighting the system's value in modeling BDD pathogenesis. Several unique shared gene targets were identified, particularly RGS16, GRO1, MAFF, and ZC3H12A. The three key BDD Treponema phylogroups elicited both distinct and shared pathogenic mechanisms in bovine foot skin; upregulating inflammation whilst simultaneously suppressing adaptive immunity. The novel gene targets identified here should enable future vaccine/therapeutic approaches.

Comparison of the therapeutic efficacy of salicylic acid paste with a polyurethane wound dressing for the treatment of digital dermatitis lesions in dairy cows.

There is little evidence of the efficacy of artificial polymers for controlling bovine digital dermatitis (BDD) as a major problem of intensive dairy productions worldwide. We therefore aimed to compare salicylic acid (SA)-based paste with a polyurethane (PU) wound dressing on a German Holstein dairy farm over a maximum 56-d period. On d 0, 109 ft with active BDD lesions from 109 cows were randomly assigned to two treatment groups: (1) SA group received a topical SA-containing paste and (2) PU group was treated with a PU wound dressing. Dressing changes were performed according to manufacturer's instructions until clinical cure (transition from active M1 or M2 to non-active M4 or healed M0 stages), whereby a clinical scoring of lesions was additionally conducted. Data from 100 ft could be analyzed (nSA = 54; nPU = 46). There was a significant reduction of the lesion score over time within each group (SA: d 0-d 14; PU: d 0-d 28, p < .05). Score differences between first (d 0) and second (SA: d 7; PU: d 14) as well as between first and third (SA: d 14; PU: d 28) evaluation did not differ significantly (p > .05). The proportion of clinically cured cows was higher in SA than in PU on d 14 (96.3 vs. 32.6%) as well as on d 28 (100 vs. 54.3%) after initial treatment (p < .05). Analysis of survival to cure in a Cox regression model showed that hazard ratio (HR) was higher for SA with PU as baseline (HR: 6.324, 95% CI: 3.625-11.033, p < .05). However, while BDD scores at enrollment did not differ between treatments (p > .05), PU had a significantly lower final BDD score (p < .05). In conclusion, evidence on the efficacy of PU bandages to treat BDD lesions is provided and further studies on bacteriological cure as well as recurrence rates are needed.

[Acute outbreak of lameness due to inflammatory claw disease in a beef herd]. / Akuter Ausbruch von Lahmheit infolge entzündlicher Klauenhauterkrankungen in einem Mastbetrieb.

INTRODUCTION: Several young bulls in a beef farm showed large, foul-smelling skin lesions in the plantar region of the coronary band and in the interdigital space. Some of the animals also had a painful, warm swelling in the palmar fetlock area. All bulls were lame (score 4/5), the most severely affected animal had a lameness score of 5/5. Initial local treatment was unsuccessful, therefore the animals received parenteral antimicrobial treatment leading to improvement of clinical signs and weight bearing in most animals. However, several animals were slaughtered prematurely due to severe foot lesions. The diverse clinical picture did not allow for diagnosing one specific claw affection without further diagnostic investigations. Histopathological and bacteriological examinations confirmed the diagnosis of digital dermatitis (DD) in combination with an interdigital phlegmon, whereby five of the seven examined specimens were positive for one or more Treponema spp. Treponemes belong to the spirochetes, the ones commonly involved in DD in dairy cows include Treponema medium, Treponema phagedenis and Treponema pedis. The last two species were detected in the present cases. The clinical findings and results of diagnostic investigations indicate that a severe form of DD complicated by a secondary infection and interdigital phlegmon caused an outbreak of severe lameness in young bulls in a beef farm. Single or combined claw diseases can be associated with severe losses not only in dairy but also in beef herds.

INTRODUCTION: Plusieurs jeunes taureaux dans une exploitation d'engraissement ont présenté, en particulier aux membres postérieurs, des lésions étendues et malodorantes au niveau plantaire de la couronne, qui s'étendaient jusqu'à l'espace interdigital. Certains animaux présentaient une enflure chaude et très douloureuse dans le pli du boulet. Les animaux étaient fortement boiteux (4/5), le taureau le plus atteint présentait une boiterie très sévère (5/5). Un traitement initial local a été mis en place, cependant, en l'absence de succès thérapeutique, les animaux ont été ensuite traités par voie parentérale avec un antibiotique, ce qui permis de réduire la sévérité du tableau clinique et d'améliorer la charge des membres atteints. En raison de la gravité des lésions, plusieurs animaux ont toutefois dû être abattus prématurément. Au vu de la diversité du tableau clinique, la maladie n'a pas pu être attribuée à une maladie des onglons particulière sans clarification supplémentaire du diagnostic. Un diagnostic de dermatite digitale en combinaison avec un phlegmon interdigital a été confirmé par l'analyse histopathologique ainsi que l'examen bactériologique: cinq des sept écouvillons examinés étaient positifs pour un ou plusieurs Treponema spp. Dans la famille des spirochètes, Treponema medium, Treponema phagedenis et Treponema pedis sont les tréponèmes le plus souvent impliqués dans la dermatite digitale chez les vaches laitières. Les deux germes mentionnés en dernier ont été mis en évidence dans les échantillons prélevés sur les taureaux d'engraissement décrits ici. L'image clinique et les résultats d'analyses des échantillons examinés suggèrent qu'une forme sévère de dermatite digitale compliquée par une infection secondaire et le développement d'un phlegmon interdigital s'est développée lors de l'épidémie de forte boiterie observée dans une exploitation d'engraissement. Les maladies des onglons, individuellement ou en combinaison, peuvent donc occasionner des pertes importantes dans les exploitations d'engraissement.

Antimicrobial activity of amixicile against Treponema denticola and other oral spirochetes associated with periodontal disease.

BACKGROUND: Periodontal disease is a polymicrobial infection characterized by inflammation of the gingiva, alveolar bone resorption and tooth loss. As periodontal disease progresses, oral treponemes (spirochetes) become dominant bacteria in periodontal pockets. Oral treponemes are anaerobes and all encode the enzyme pyruvate-ferredoxin oxidoreductase (PFOR) which catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA. Here we assess the susceptibility of oral treponemes to amixicile (AMIX), a novel inhibitor of PFOR. METHODS: The minimum inhibitory concentration (MIC) of AMIX against several oral treponeme species was determined. The impact of AMIX on processes relevant to virulence including motility, H2 S production, and complement evasion were determined. RESULTS: The growth of all oral treponeme species tested was inhibited by AMIX with MIC concentrations (MIC) ranging from 0.5-1.5 µg/mL. AMIX significantly reduced motility, caused a dose-dependent decrease in hydrogen sulfide production and increased sensitivity to killing by human complement (i.e., serum sensitivity). CONCLUSIONS: AMIX is effective in vitro in inhibiting growth and other processes central to virulence. AMIX could serve could serve as a new selective therapeutic tool for the treatment of periodontal disease.

Bovine digital dermatitis: Current concepts from laboratory to farm.

Bovine digital dermatitis (DD) is a severe infectious disease causing lameness in dairy cattle worldwide and is an important ruminant welfare problem that has considerable economic issues. Bovine DD is endemic in many regions worldwide and it is important to understand this major disease so that effective control strategies can be identified. There is substantial evidence that specific treponeme phylotypes play an important causative role in bovine DD. This review considers current research, including DD Treponema spp. investigations, associated DD pathobiology, and current and potential treatment and control options. Epidemiological data, alongside new microbiological data, help delineate important transmission routes and reservoirs of infection that allow effective interventions to be identified. Better on-farm housing hygiene, pasture access, routine footbathing and claw trimming with disinfected equipment need to be implemented to significantly reduce the incidence of DD. There is a paucity of peer reviewed research into both commonly used and novel treatments. In vitro antimicrobial susceptibility studies of DD treponemes and effective treatment of human treponematoses clearly indicate that antibiotics frequently selected for DD treatments are not the most efficacious. Whilst there are understandable concerns over milk withdrawal times in dairy cattle, more needs to be done to identify, license and implement more appropriate antibiotic treatments, since continued overuse of less efficacious antibiotics, applied incorrectly, will lead to increased disease recurrence and transmission. More research is needed into methods of preventing DD that circumvent the use of antibiotics, including vaccination and transmission blocking studies, to reduce or hopefully eradicate DD in the future.

A molecular epidemiology of treponemes in beef cattle digital dermatitis lesions and comparative analyses with sheep contagious ovine digital dermatitis and dairy cattle digital dermatitis lesions.

Bovine digital dermatitis (BDD) is an infective foot disease commonly reported in dairy cattle where Treponema are considered as the primary causative infectious agents. There still remains little definitive information on the etiology of BDD in beef cattle suggesting further investigations are warranted. Beef BDD lesions (n=34) and healthy beef foot tissues (n=38) were analysed by PCR for three BDD-associated Treponema phylogroups and also for Dichelobacter nodosus and Fusobacterium necrophorum. Spirochete culture was attempted on all BDD lesion samples. One or more BDD-associated Treponema phylogroups were detected in 100% of beef BDD lesions. "Treponema medium/Treponema vincentii-like", "Treponema phagedenis-like" and Treponema pedis spirochetes were identified in 27/34 (79%), 31/34 (91%) and 24/34 (71%) of BDD lesions, respectively. No BDD-associated treponeme DNA was amplified from beef healthy foot tissues. D. nodosus and F. necrophorum were present in 24/34 (71%) and 15/34 (44%) of lesions and 10/38 (26%) and 12/38 (32%) of healthy foot tissues, respectively. Twenty spirochetes were isolated from beef BDD lesions; 19 were representatives of the three BDD-associated Treponema phylogroups. One spirochete isolate shared less than 97% 16S rRNA gene similarity to the three cultivable BDD-associated Treponema phylogroups and therefore may represent a novel taxa of Treponema. Upon comparison, sheep contagious ovine digital dermatitis (CODD), dairy cattle and beef cattle BDD lesions appear to have extremely similar bacteriological data and therefore provides evidence of a shared etiopathogenesis posing concerns for cross-species transmission.

The etiology of digital dermatitis in ruminants: recent perspectives.

Digital dermatitis (DD) is a multifactorial polymicrobial infectious disease originally described in dairy cattle, but is increasingly recognized in beef cattle, sheep, and more recently, elk and goats. Clinical bovine lesions typically appear on the plantar surface of the hind foot from the interdigital space and heel bulb to the accessory digits, with a predilection for skin-horn junctions. Lesions present as a painful ulcerative acute or chronic inflammatory process with differing degrees of severity. This variability reflects disease progression and results in a number of different clinical descriptions with overlapping pathologies that ultimately have a related bacterial etiology. The goal of this review article is to provide a concise overview of our current understanding on digital dermatitis disease to facilitate clinical recognition, our current understanding on the causative agents, and recent advances in our understanding of disease transmission.

Digital Dermatitis in Cattle: Current Bacterial and Immunological Findings.

Globally; digital dermatitis is a leading form of lameness observed in production dairy cattle. While the precise etiology remains to be determined; the disease is clearly associated with infection by numerous species of treponemes; in addition to other anaerobic bacteria. The goal of this review article is to provide an overview of the current literature; focusing on discussion of the polybacterial nature of the digital dermatitis disease complex and host immune response. Several phylotypes of treponemes have been identified; some of which correlate with location in the lesion and some with stages of lesion development. Local innate immune responses may contribute to the proliferative, inflammatory conditions that perpetuate digital dermatitis lesions. While serum antibody is produced to bacterial antigens in the lesions, little is known about cellular-based immunity. Studies are still required to delineate the pathogenic traits of treponemes associated with digital dermatitis; and other host factors that mediate pathology and protection of digital dermatitis lesions.

The Cross-Talk between Spirochetal Lipoproteins and Immunity.

Spirochetal diseases such as syphilis, Lyme disease, and leptospirosis are major threats to public health. However, the immunopathogenesis of these diseases has not been fully elucidated. Spirochetes interact with the host through various structural components such as lipopolysaccharides (LPS), surface lipoproteins, and glycolipids. Although spirochetal antigens such as LPS and glycolipids may contribute to the inflammatory response during spirochetal infections, spirochetes such as Treponema pallidum and Borrelia burgdorferi lack LPS. Lipoproteins are most abundant proteins that are expressed in all spirochetes and often determine how spirochetes interact with their environment. Lipoproteins are pro-inflammatory, may regulate responses from both innate and adaptive immunity and enable the spirochetes to adhere to the host or the tick midgut or to evade the immune system. However, most of the spirochetal lipoproteins have unknown function. Herein, the immunomodulatory effects of spirochetal lipoproteins are reviewed and are grouped into two main categories: effects related to immune evasion and effects related to immune activation. Understanding lipoprotein-induced immunomodulation will aid in elucidating innate immunopathogenesis processes and subsequent adaptive mechanisms potentially relevant to spirochetal disease vaccine development and to inflammatory events associated with spirochetal diseases.

Dermatitis digital en novillos de feedlot: Descripción de 2 brotes en el Noroeste Argentino

La Dermatitis Digital (DD) es una afección podal de distribución mundial. Al igual que otras enfermedades que afectan al pie bovino induce evidentes cojeras, con las consecuentes pérdidas productivas y económicas. Comúnmente se la describe en el ganado lechero y raramente en ganado de carne. En este trabajo se presentan dos brotes de DD en novillos de feedlot del Noroeste Argentino. Se destacan aspectos clínicos, epidemiológicos, patológicos y de diagnóstico. La incidencia fue de 5 y 35 %. Las lesiones se identificaron típicamente en el área palmar de los miembros posteriores e histopatológicamente se observó una dermatitis necrotizante con infiltrado neutrofílico. Mediante la tinción Warthin-Starry se identificaron espiroquetas intralesionales en el 50% (4/8) de las muestras colectadas.

Digital Dermatitis (DD) is a podal condition of worldwide distribution. Like other diseases that affect the bovine foot, it induces obvious lameness, with consequent productive and economic losses. It is commonly described in dairy cattle and descriptions in beef cattle are scarce. In this paper, two DD outbreaks are described in steers from feed-lot in the Argentine Northwest. Emphasis is given to more relevant aspects of clinical, epidemiological, pathological and diagnostic findings. The incidence was 5 and 35%. Lesions are typically identified in the palmar area of the hind limbs, and a necrotizing dermatitis with neutrophil infiltrate was observed histopathologically. By Warthin-Starry staining was identified an intralesional spirochetes in 50% (4/8) of collected samples.