Pathology and bacteria related to digital dermatitis in dairy cattle in all year round grazing system in Brazil

Abstract

Digital dermatitis (DD) is one of the main causes of lameness in dairy cattle worldwide, and it is frequently reported in high-yielding, free stall dairy herds from regions with a temperate climate. However, DD is also observed with high prevalence in grazing cattle with a low milk yield in tropical regions. To clarify whether these differences have an impact on the etiology of the disease, we studied DD lesions from all year round grazing cattle of mixed breed in Brazil using high-throughput 16S rRNA gene sequencing and fluorescent in situ hybridization. The study included samples from 66 skin lesions and 5 healthy skins collected from five farms. Both techniques showed Treponema spp. to be the most abundant bacteria, present in all but one of the samples with minimal epidermal alterations. We identified eleven different Treponema strains belonging to the six major phylotypes of Treponema which have all previously been identified in DD lesions. Furthermore, we identify Dichelobacter nodosus in DD lesions by gene sequencing and also by fluorescent in situ hybridization in almost half of biopsy specimens in areas with mild epithelial damage and together with Treponema. The present data support the hypothesis that Treponema constitutes the main pathogen responsible for DD, independent of the environment and region where cows are kept, and it further suggests D. nodosus as another potentially important pathogen.

Microbiome Shift, Diversity, and Overabundance of Opportunistic Pathogens in Bovine Digital Dermatitis Revealed by 16S rRNA Amplicon Sequencing

“…The abundance data previously presented by Mamuad et al, (2020) [ 16 ], to some extent, agree with the reports of Moreira et al, (2018) [ 14 ], Zinicola et al, (2015) [ 11 ], Beninger et al, (2016) [ 26 ], Krull et al, (2014) [ 13 ], and Nielsen et al, (2016) [ 12 ], that BDD is polybacterial, with Treponema spp., as the most abundant genus. However, the dominance and diversity of species under this genus still varies between reports from different geographical locations.…”

“…Given that certain members of genus Treponema are recognized as the abundant bacteria, and considered as major contributors in the development and progression of the disease, other bacterial genera have also been reported in BDD from other countries as also in this study such as Porphyromonas [ 14 ], Campylobacter , Acholeplasma [ 11 ], Peptoniphilus and Romboutsia [ 27 ]. In this study, a major abundance of Carboxylicivirga mesophila and Treponema lecithinolyticum was observed as the fourth and fifth most abundant identified bacteria in BDD, respectively, which were not observed from previous studies.…”

“…Many reports have attempted to elucidate the association of the microbiome of BDD towards disease development [ 11 , 13 , 14 , 15 ]. Surprisingly, for more than 20 years since it emerged as a major problem in the cattle industry in certain countries, studies on BDD have just recently started in Korea.…”

Genotypic and Phenotypic Characterization of Treponema phagedenis from Bovine Digital Dermatitis

“…For almost half a decade since the initial report of BDD in Italy [ 6 ], BDD has been subsequently reported in various parts of the world, reaching an endemic state in many countries [ 7 ]. Some studies on BDD have focused on determining its etiology and pathogenesis with the expectation of developing an efficient treatment [ 8 ].…”

“…are consistently described in BDD lesions [ 7 , 9 , 10 ], suggesting it as polytreponemal [ 4 , 11 ]. Thus far, three phylogroups— T. pedis , T. medium , and T. phagedenis —have been reported as being the most prevalent and abundant [ 7 , 12 ]. Among these, T. phagedenis is considered a key agent in the pathogenesis due to the fact of its presence in the interface with healthy tissues [ 13 ].…”