The isolation of an atypical mycobacterium from three wood pigeons with tuberculosis-like lesions

Cultural and biological tests were carried out on the livers and spleens of three wood pigeons. Acid-fast organisms were observed in histological sections and smears taken from tuberculosis-like lesions in the organs. Biological tests revealed that all the isolates sensitised the guinea pig to avian tuberculin. One was pathogenic for chickens while the remaining two were non-pathogenic. All were non-pathogenic for rabbits and domestic pigeons. The organisms could not be cultured on conventional media for Mycobacterium tuberculosis or media containing mycobactin. However they were readily maintained on 7H11 media. These results indicate a separate species of mycobacterium related to M avium.