Pathogenicity of Mycobacterium avium Serovar 1 Isolated from Swine in Japan for the First Time.

A total of 116 strains of Mycobacterium avium-intracellulare complex were isolated from swine with tuberculous lesions at meat inspection, during 1982-1983. Of them, one strain isolated from the lesion in the mesenteric lymph nodes was identified as M. avium serovar 1 (swine strain). The pathogenicity of the swine strain in chickens was compared with that of a reference strain (M. avium serovar 1). Chickens were inoculated intravenously with each strain (2 x 10(6) colony forming units: CFU) and they were autopsied at 30 days after inoculation. Enlargement of the liver, spleen and kidney was observed in the inoculated chickens. In histopathological examination, many granulomatous lesions were observed in the lung, liver and spleen. Infiltration of lymphocytes was found in the kidney and pancreas. Both inoculated organisms were recovered from the liver (10(3)-10(6) CFU/g) and spleen (10(3)-10(5) CFU/g) of each inoculated chicken. The reference strain (< 3.0 x 10(2) CFU/g, ml) was also recovered from the lung, kidney, pancreas and the bile of the inoculated chickens. All the isolates were identified as serovar 1. It was shown that the swine strain had pathogenicity in chickens comparable to that of the reference strain.