Differences in the sensitivity of pneumococci to sulfapyridine have been suggested since the earliest days of its use.1 MacLean, Rogers and Fleming2 observed decided differences both in vivo and in vitro, and developed, as did Macleod and Daddi,3 a strain resistant to sulfapyridine by passage of a sensitive strain through treated mice. These observations have been confirmed and extended4 and may be summarized as follows: Pneumococci differ profoundly in their sensitivity to the sulfonamides; resistant strains occur in nature; sensitive strains may become resistant when they are exposed to the drug in either the test tube, mouse or human being; resistant strains are probably permanently resistant.
The clinical implications of these results are most grave. The rational therapy of pneumococcic pneumonia demands knowledge of the sensitivity or resistance of the organism: chemotherapy in the absence of this knowledge is analogous to serotherapy in the absence of
Moore FJ, Thomas RE, Hoyt A. SENSITIVITY OF PNEUMOCOCCI TO SULFAPYRIDINE: A RAPID QUALITATIVE TEST FOR RESISTANCE; CLINICAL EVALUATION OF THE PROBLEM. JAMA. 1941;117(6):437–439. doi:10.1001/jama.1941.72820320002007a