STUDIES ON SULFONAMIDE-RESISTANT ORGANISMS: I. DEVELOPMENT OF SULFAPYRIDINE RESISTANCE BY PNEUMOCOCCI

Abstract

(1) One strain of type I and two strains of type III pneumococcus were made highly resistant to sulfapyridine by serial passage through mice treated with less than curative doses of this drug. The organisms that were made resistant in vivo were also resistant to sulfapyridine in vitro. (2) A sulfapyridine-sensitive strain of type II pneumococcus was made highly resistant to this drug by serial passage through broth containing increasing concentrations of sulfapyridine. This resistant organism was also insensitive in vivo. (3) Sulfapyridine resistance was retained by the above strains for more than 200 passages through untreated mice. (4) The manner in which resistant strains are developed and possible explanations for sulfonamide resistance were mentioned and discussed.