Abstract
Summary
Summary.
Four strains of pneumococci naturally resistant to sulfonamide action have been shown by mouse protection tests to be readily susceptible to the action of penicillin. When infection and treatment were both given intraperitoneally a single dose of one Florey unit protected 84%, and 10 Florey units protected 95% of the treated mice; 6 doses of one Florey unit per dose protected 90% and 6 doses of 10 Florey units protected 99% of the treated mice. When infection was given intraperitoneally and treatment subcutaneously a single dose of 10 Florey units protected 3576, and 100 Florey units protected 100% of the treated mice.
Cultures of PnII 617 and 807 after growth in penicillin broth for a short time were resistant to twice the previously inhibitory concentration. No difference in resistance could be shown by mouse protection test.
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