Studies of the Action of Sulfonamides upon the Bacterial Cell

Abstract

The mode of action of sulfonamides upon susceptible bacterial species has been the subject of much study. It appeared to us that one of the most fundamental aspects of this problem was to determine whether active compounds differ from closely related inactive substances in their respective abilities to reach or penetrate the bacterial cell. It was conceivable that p-aminobenzene sulfonamide (sulfanilamide) diffuses into the streptococcal cell (and is concerned in its metabolism) whereas its chemotherapeutically inert isomers, the ortho and meta compounds, do not diffuse into the organism. Since this does not appear to be true, the inactivity of certain compounds cannot be explained by this one fundamental property. In the light of our results diffusion into the organism may or may not be a requisite for a chemotherapeutic agent.

Twenty-liter batches of broth cultures of Streptococcus hemolyticus, strain C-203, were grown for 48 hours. The organisms were then collected by means of a continuous flow Sharples centrifuge and washed with 250 cc normal saline 6 to 8 times. The cells were collected after each washing by means of horizontal centrifugation. After final washing the bacteria were dried over P₂O₅ in a vacuum desiccator. The same procedure was repeated with cultures in broth containing 20 mg % sulfanilamide, orthanilamide and metanilamide, respectively. The drug broth cultured bacteria were washed 6 to 8 times until the wash fluid contained no demonstrable sulfonamide compound as determined by the Marshall test. Accurately weighed samples of dried organisms from each of these test cultures were quantitatively extracted in 3% trichloracetic acid for 2 hours at 37°C and the amount of each substance so eluted was also determined by the Marshall method.