Abstract
Summary and Conclusions
Nicotinic acid, thiamin chloride, cocarboxylase, riboflavin, pyridoxine and para-amino benzoic acid have been shown to have no effect on the photometrically determined growth rate of S. aureus and E. coli in simple media. Calcium pantothenate definitely accelerated the rate of multiplication of S. aureus but not of E. coli when present in a concentration of 200 μg per milliliter. None of these substances except para-amino benzoic acid antagonized sulfathiazole bacteriostasis although present in amounts 40 times as great as the sulfonamide. Concentrations of sulfonamide 2,500 times that of the accompanying para-amino benzoic acid were completely ineffective in inhibiting bacterial growth.
These observations, therefore, support the view that the sulfonamides directly affect that part of the microbial metabolic system which specifically utilizes para-amino benzoic acid, since relatively large amounts of 6 other important growth factors completely failed to inhibit their bacteriostatic activity.
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