Bacteriological and Epidemiological Studies of Pulmonary Diseases Associated with Atypical Acid-Fast Bacilli

Publisher Website
Google Scholar
Abstract
Preliminary bacteriological, epidemiological and clinical studies were made on 108 individuals in Florida found to be discharging atypical acid-fast bacilli in their sputum. Initial isolations from 22 of the cases were made from sputum specimens submitted first to the public health laboratories, the remainder were from hospitalized cases and a clinical pathological laboratory. Primary isolations of atypical acid-fast bacilli were made on Lowenstein-Jensen medium incubated at 37[degree] C from 3 to 8 weeks. The growth rates correspond closely to Mycobacterium tuberculosis. Colonial and cellular morphology are discussed. Variations of the characteristics are found among the atypical acid-fast bacilli and differences are noted within the group as a whole as compared to M. tuberculosis. Further tests were used to characterize the atypical strains. Seventy-two of 75 strains tested gave strongly positive catalase reactions. Distinctive serpentine cord formation could not be demonstrated. All strains grew both at room temperature and at 37[degree]. Three types of atypical strains are identified on the basis of pigment production when grown in the presence or absence of light. The types are photochromogens, non-photochromogens and scotochromes. When examined by the neutral red cytochemical test variable results were obtained. Of 56 strains tested in the dba strain of mice, 29 were pathogenic where as of 73 strains tested in guinea pigs, none of the strains produced generalized progressive disease. Most of the strains were found to be highly or partially resistant to p-amino-salicylic acid and isonicotinic acid hydrazide, while they were somewhat susceptible to streptomycin. Epidemiologieal findings suggest that these infections are selective for white males in the older age groups. The relative rarity of atypical acid-fast bacilli in negroes was striking. There were no clinical findings in the cases to differentiate them from those with infections due to M. tuberculosis. The most outstanding clinical feature was the lack of favorable response to antituberculous drug therapy. The findings to date call for long range coordinated studies involving bacteriologists, epidemiologists and clinicians.