Resistance-enhancing Activity of Culture Filtrates of Mycobacterium Tuberculosis.

Hedgecock, Loyd W. (Veterans Administration Hsopital, St. Louis, Mo.). Resistance-enhancing activity of culture filtrates of Mycobacterium tuberculosis. J. Bacteriol. 88:1349-1355. 1964.-It was demonstrated that filtrates of cultures of Mycobacterium tuberculosis exhibit resistance-enhancing activity against infection with Klebsiella pneumoniae and Diplococcus pneumoniae. Resistance was demonstrable when the culture filtrate was injected 3 hr prior to challenge with K. pneumoniae, and reached the highest level when injected 24 hr before challenge. Protection was maximal when the filtrate and challenging organisms were injected by the same route. After infection with K. pneumoniae, the bacterial titers in the tissues of filtrate-treated animals were significantly lower than those of untreated susceptible controls. Mice injected with the filtrate 24 hr previously demonstrated significantly increased rates of clearance of injected carbon from the blood. In examination of a variety of mycobacteria, resistance-enhancing activity was found only in culture-filtrates of pathogenic mycobacteria, the highest concentration occurring in filtrates of virulent organisms. The injection of a relatively large amount of phenol-killed cells of all of the mycobacteria examined enhanced resistance to infection with K. pneumoniae.