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Atypical Dermatophilus congolensis infection in a three-year-old pony
Barbara A Byrne1, Courtney L Rand, Valerie R McElliott
1Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA. bbyrne@ucdavis.edu
Abstract:
Dermatophilosis caused by Dermatophilus congolensis causes exudative dermatitis in a variety of species. The infection is generally limited to the cutaneous tissues, where infection is acquired from the environment and bacteria penetrate into keratinized epithelium through epithelial disruption. A 3-year-old pony filly was examined for enlarging mandibular lymph nodes during the preceding 10 months. Biopsy of the node revealed mixed and granulomatous inflammation and thick, filamentous Gram-positive bacteria. Dermatophilus congolensis, confirmed by biochemical testing and sequencing of the ribosomal RNA gene, was cultured from a sample aspirated from the infected site. Dermatophilus congolensis should be considered as a possible etiologic agent associated with lymphadenopathy and granulomatous inflammation in the horse.
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