Abstract
This study aimed to isolate and characterize Treponema spp. from bovine digital dermatitis (BDD)-infected dairy cattle. Seven isolates were characterized in this study. Isolates exhibited slow growth, and colonies penetrated the agar and exhibited weak β-hemolysis. Round bodies were observed in old and antibiotic-treated cultures. Cells ranged from 9–12 µm in length, 0.2–2.5 µm in width, and were moderately spiraled. The 16S rRNA analysis revealed the isolates as Treponema phagedenis with >99% sequence homology. Isolates had alkaline phosphatase, acid phosphatase, β-galactosidase, N-acetyl-β-glucosaminidase, esterase (C4), esterase lipase (C8), naphthol-AS-BI-phosphohydrolase, and β-glucuronidase activities. Low concentrations of ampicillin, erythromycin, and tetracycline were required to inhibit the growth of isolates. Formic, acetic, and butyric acids were produced, while propionic acid was significantly utilized, indicating its essentiality for treponemal growth. The isolates shared the same characteristics and, therefore, were considered as a single strain. Isolate HNL4 was deposited as a representative isolate (Treponema phagedenis KS1). The average nucleotide identity of strain KS1 showed a small difference with the human strain (99.14%) compared with bovine strain (99.72%). This study was the first to isolate and characterize Treponema phagedenis from BDD in Korea and, hence, it delivered pathogenicity-related insights and provided valuable information that can be used for the management of BDD.
Highlights
Bovine digital dermatitis (BDD) is an important infectious foot disease causing lameness in cattle [1]
This study reports the characterization of the first successfully isolated Treponema spp. in Korea from dairy cattle with bovine digital dermatitis
Difficulties in culturing BDD-associated treponemes, due to the fact of their fastidiousness has restricted the number of isolates and the recovery of treponemes collected from lesion samples
Summary
Bovine digital dermatitis (BDD) is an important infectious foot disease causing lameness in cattle [1]. Characterized by ulcerative dermatitis, it later forms a hyperkeratotic papillomatous lesion [2] which is highly painful and sensitive when touched or manipulated, and it often leads to bleeding [3]. Serious issues associated with BDD lead to increasing concerns about the reduced welfare of the animal as well as significant economic losses due to the facts of reduced milk yield, premature culling, and poor reproductive performance [5]. T. phagedenis is considered a key agent in the pathogenesis due to the fact of its presence in the interface with healthy tissues [13]
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