Dermatophilosis is an acute or chronic exudative dermatitis caused by the bacterium Dermatophilus congolensis. Dermatophilus congolensis is a pleomorphic, Gram-positive actinomycete that infects animals and humans. Frequently, there is a misdiagnosis of this infection because of the high similarity of this organism with other members of the family Actinomycetaceae. The present study was carried out to isolate and identify the causative agent from a cattle herd clinically suspected for dermatophilosis associated with lower leg dermatitis in the Puducherry region (Southern India), their predisposing factors and treatment. The microscopic examination of skin impression smears from the infected animals did not reveal the characteristic appearance of Dermatophilus congolensis. Microscopic examination of the isolated bacteria revealed Gram-positive bacteria with filamentous structures and was further confirmed by polymerase chain reaction (PCR) targeting the 16S rRNA of Dermatophilus congolensis. This study supports the PCR technique as a preferable technique to the conventional microscopy and culture techniques for the confirmation of D. congolensis infection during epidemiological surveys. The contact of skin with sewage channels in grazing areas and the wetting of skin by rain may be the predisposing factors for transmission by direct contact with clinically infected animals. Based on the antibiogram, the isolates were sensitive to antibiotics such as Gentamicin, Penicillin, Amikacin, Enrofloxacin and Chloramphenicol. The animals with dermatophilosis were treated with fortified procaine penicillin and streptomycin intramuscularly along with supportive drugs and topical dressing with 1% povidone-iodine for successive five days, which resulted in a fast and complete recovery. 

Highlights

• Confirmatory diagnosis of bovine dermatophilosis was done by PCR targeting the 16S rRNA of Dermatophilus congolensis.
• Dermatophilosis affected animals effectively treated with antibiotics along with supportive treatment.