The Attenuating Effect of Promin on Virulence of the Tubercle Bacillus

It has been shown previously that p, p'-diaminodiphenylsulfone-N-N'-dextrose sulfonate (promin) in concentrations of 20 mg % inhibits the growth of the tubercle bacillus in culture media. 1 Also promin administered orally 1 or in the diet² retards the tuberculous process in guinea pigs. To determine the mechanism of the action of promin upon the virulence of the tubercle bacillus experiments were designed to ascertain the effect of prolonged cultivation of the bacillus on the medium containing the drug in low concentrations. Changes in virulence of the strain were determined by the degree of invasiveness of the attenuated strain, (a) when inoculated upon the chorio-allantoic membrane of the chick embryo and (b) when inoculated intraperitoneally into guinea pigs.

Methods. The A 27 strain of human tubercle bacilli was selected since this strain was known to have a moderately high degree of virulence. The bacilli were grown in a culture medium consisting of beef bouillon plus 5% glycerine with 10 mg % of promin. Preliminary experiments had shown that the strain could not survive this concentration of promin continuously; hence, after the second transfer into the medium containing promin, the strain was returned to the control medium.