Further Studies on the Action of Sulfapyridine on Pneumococci

[摘要] A series of experiments is presented in which type III pneumococci were grown in various ways in artificial media, both with and without sulfapyridine, in order to determine whether the changes which take place in the medium or in the organisms during the course of growth have any effect on subsequent growth in such media.When sulfapyridine was added during the various phases of active growth from a small inoculum, there followed, in turn, a period in which multiplication continued, a bacteriostatic and then a decline phase. The latter effects were limited only by the population of the culture at the time the drug was added, and the amount of multiplication that preceded was fairly constant within that limit.The growth of pneumococci in fresh media was dependent on the conditions under which they had been grown previously. Organisms in the static or in the decline phase of sulfapyridine action continued to die when transferred to fresh drug-containing media, as if the media had not been changed. When transferred to drug-free media they grew like a fresh inoculum of similar size that had previously grown without drug. Within the limits of the experiment, therefore, sulfapyridine action is reversible.The action of sulfapyridine effects a change in the organism and not in the medium. This change was shown to take place even in the presence of a large inoculum when growth inhibition was not apparent, and it became manifest when small numbers of the organisms were transferred to fresh drug-containing media.Pneumococci were grown repeatedly from fresh small inocula in sulfapyridine broth in which all the phases of growth, bacteriostasis and bactericidal action had previously been carried to completion. All the resulting growth curves were essentially the same. The inhibition or killing of pneumococci was not accompanied by any stable change in the media capable of modifying the growth of fresh organism subsequently inoculated.The population of a culture that had attained the static phase of sulfapyridine action was doubled by the addition of fresh organisms that had grown without sulfapyridine. The resulting population-curve of that culture from that point on was the same as that of a control culture of the new inoculum in fresh sulfapyridine broth. This suggests that no unstable changes are produced during the growth of pneumococci in sulfapyridine-containing media that are capable of modifying the growth of freshly inoculated organisms.

[学科分类] 生物科学（综合）