Abstract
A grass bacillus indistinguishable in the characteristic cultural and morphological earmarks from the tubercle bacillus was isolated 6 years ago. Its acid fastness was variable even in cultures isolated from a single cell. Under certain conditions it developed non-acid-fast granules which were filtered through a Berkefeld N candle. These underwent slow and capricious germination to a non-acid-fast, diphtheroidal bacillus whose cultural characters were quite different from the antecedent strain. Microscopically, however, the strains were almost indistinguishable.
In 4 out of 6 years of the intervening period, and always in the spring of the year, the identical diphtheroid has spontaneously dissociated from the original strain, indicating that the mechanism for such dissociation is via the filtrable gonidial granule. (Much.)
More recently, by employing a modified K-medium (Kendall) these observations have been repeated and extended; for in addition to the diphtheroidal form, the original cultural stage of the organism has been recovered from the filtrates. A strain of bovine tubercle bacillus has also dissociated a very similar diphtheroidal strain, often containing numerous acid-fast granules.
These strains differ in no essential particular from the diphtheroids of Hodgkin's disease, benign lymphogranulomatosis and Roeck's sarcoid, making it highly probable that their origin in vivo is also the tubercle bacillus. No opinion is vouchsafed in respect of their role in the pathogenesis of such diseases.
For almost 30 years non-acid-fast forms have been described for tubercle bacillus by various workers, but their mechanism of origin has never been clear and the strains themselves were viewed as contaminants.
This final demonstration that single-celled cultures of the acid-fast group possess filtrable phases, biologically distinct, should settle this moot problem of the filtrability of acid-fast bacilli; it explains in addition the origin of certain non-acid-fast strains and may lead to their better evaluation in certain atypical forms of tuberculosis.
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