Browsing by Author "Beninger, Caroline"
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- ItemOpen AccessAssociations between digital dermatitis lesion grades in dairy cattle and the quantities of four Treponema species(2018-10-29) Beninger, Caroline; Naqvi, Syed A; Naushad, Sohail; Orsel, Karin; Luby, Chris; Derakhshani, Hooman; Khafipour, Ehsan; De Buck, JeroenAbstract Digital dermatitis (DD) presents as painful, ulcerative or proliferative lesions that lead to bovine lameness affecting economic efficiency and animal welfare. Although DD etiological agent(s) have not been established, it is widely accepted that DD is a polymicrobial disease significantly associated with species of Treponema and the non-linear disease progression may be attributed to interactions among infecting bacteria. We postulated the morphological changes associated with DD lesion grades are related to interactions among infecting species of Treponema. We developed a novel species-specific qPCR that can identify the absolute abundance of the four of the most common species of Treponema in DD, T. phagedenis, T. medium, T. pedis and T. denticola, in a single reaction. We found species abundance and the number of distinct Treponema species present is higher in active, ulcerative lesions than in healing lesions, chronic lesions, and DD-free skin. Treponema spp. were present in both DD-free skin and M3 lesions following treatment with oxytetracycline. We have also found positive correlations among T. phagedenis, T. medium and T. pedis indicating they are significantly more likely to be found together than apart and their absolute quantities tend to increase together, a relationship which is not present with T. denticola. Further, we found Treponema, particularly viable T. denticola, in lesions 5 days post treatment with oxytetracycline (M3). Our findings suggest that pathogenicity may be closely associated with Treponema abundance, particularly T. phagedenis, T. medium and T. pedis, and interactions among them, independent of T. denticola. Our results provide a novel, consistent method to identify species of Treponema within DD lesions and associate Treponema spp. and abundance with morphological changes related to host pathogenicity.
- ItemOpen AccessDistribution of Treponema species and antimicrobial resistance genes in digital dermatitis lesions(2018-08-04) Beninger, Caroline; De Buck, Jeroen M.; Orsel, Karin; Morck, Douglas W.Digital dermatitis lesions are ulcerative or proliferative masses between the heel bulbs. The most significant clinical outcome of digital dermatitis (DD) is lameness, leading to animal welfare concerns and economic loss for dairy producers worldwide due to premature culling, milk loss, and decreased fertility. While there is insufficient evidence to determine the etiological agent(s) responsible for DD, it is widely accepted that DD is a polymicrobial disease significantly associated with anaerobic bacteria, Treponema. Difficulties in obtaining pure cultures and the nearly exclusive presence of Treponema in diseases as members of a polytreponemal or polymicrobial communities has led to insufficient species identification within lesions and incomparable prevalence estimates based on phylotype. Our primary research objectives were to develop a diagnostic tool to identify Treponema spp. within DD lesions to associate presence and abundance with DD lesion grades. Further, we examined the distribution of antimicrobial resistance genes (AMGs) within sequenced isolates of DD-associated Treponema and designed targeted PCR for Treponema AMGs (AMGsTrep) within lesions. We provide significant evidence that the absolute quantities of Treponema and AMGsTrep are lower in chronic and early, active DD lesions suggesting Treponema spp. within these lesions may be more susceptible to antimicrobials (AMs) compared to species in advanced, active lesions. We have identified potential interactions among Treponema spp. that may facilitate DD progression and enhance pathogenicity and may affect AM susceptibility and lesion chronicity. With the novel diagnostic tool developed here, future research should elucidate interactions among Treponema spp. and in vitro susceptibility profiles and the efficacy of treating early and chronic lesions compared to advanced, active lesions on infection resolution.