Isolation of Mycobacteria from Lymph Nodes of Pigs and Their Environment

Abstract

An attempt was made to isolate mycobacteria from the lymph nodes (LNs) of 459 pigs at four abattoirs (Obihiro, Tokachi-Shimizu, Fukagawa, and Kushiro). From 156 pigs selected at random at Tokachi-Shimizu highly contaminated with mycobacteria were isolated at 49% (29/59) in the submaxillary LN and 20% (13/65) in the mesenteric LN. The average isolation rates of mycobacteria from the lymph node in all the pigs, except those at Tokachi-Shimizu were as follows: 5.4% (16/294) from the submaxillary, 3.8% (11/293) from the pulmonary, and l.7% (5/298) from the mesenteric LN. When broken by the abattoir, they were 7% (7/100) at Fukagawa, 7.8% (8/102) at Kushiro, and 13.8% (14/101) at Obihiro. The average being 9.57% (29/303). It was found that 3 pigs harbored mycobacteria concurrently in two lymph nodes. A total of 76 strains of the mycobacterial isolates did not belonged to Mycobacterium tubercculosis or M. bovis, but a majority of them were so-called atypical mycobacteria. Of them, Runyon's Group III organisms were predominant and most of them identified as M. intracellulare serovars. M. avium serovar 1 was isolated from two pigs at Tokachi-Shimizu and Obihiro, respectively. This is the first isolation of M. avium in Hokkaido. From 202 environmental specimens collected, 17 strains of mycobacteria were isolated. It is known that the strains of serovars 4, 6, and 8 of M. intracellulare, which are potentially pathogenic for man and animals, have been isolated from soil, sewage and beddings. Isolation of M. intracellulare from soil, sewage and beddings is a new finding in Japan.