The relationship of atypical acid-fast bacteria to human disease; a preliminary report.

Abstract

Abstract Acid-fast organisms differing from known human or bovine tuberculosis strains have been isolated from eighty-eight patients. Although some appear to be intimately associated with pulmonary disease in man, none was virulent for guinea pigs inoculated with 1 mg. of organisms. It was possible to divide the organisms tentatively into three groups on the basis of colonial characteristics. Two of the groups (I and III) were found to be virulent for mice while the other was not. The taxonomic identity of the organisms described has not yet been established. Colonial and growth characteristics of the three groups are described. Certain of the strains show some resemblance to avian or vole bacilli. The organisms displaying mouse virulence are characterized by repeated occurrence over long periods of time iii sputa from the same patients, none of whom were found to have concurrent infection with M. tuberculosis . Seven of these strains were found directly in diseased human lung tissue. Twenty-four of these strains were tested for virulence in mice, and all caused lung lesions. On the other hand, seventeen strains of Group II showed no virulence for mice and were not as consistently associated with human disease. These organisms were found in lower concentration in original specimens and a greater proportion of them was isolated from gastric washings. Furthermore, several were from patients harboring typical tubercle bacilli as well. In the light of these findings, discard of an acid-fast organism isolated from a patient with pulmonary disease because it fails to fit the cultural or virulence pattern of M. tuberculosis does not appear justified.