The Tuberculostatic Action of para -Aminosalicylic Acid

Abstract

P-Aminosalicylic acid was found to be highly bacteriostatic in vitro for virulent human type tubercle bacilli, and this activity was not appreciably affected by the presence of serum in the medium. The bacteriostatic activity was partially reversed by p-aminobenzoic acid but not by Na salicylate, and was inversely proportional to the no. of organisms present. One avirulent, rapidly growing, acid-fast organism, no. 607, was not inhibited by 100 mg. % p-aminosalicylic acid. 13 derivatives of PAS and salicylic acid were found to be much less tuberculostatic than PAS. Exptl. tuberculosis of mice was suppressed by p-aminosalicylic acid adm. in the diet in 1% and 2% concs., both when the drug was given as the hydrochloride and as the free base. 4% p-aminosalicylic acid was highly toxic to mice; 2% was slightly toxic. PAS and streptomycin when adm. to mice simultaneously appeared to exert a suppressive effect on the tuberculous process greater than that of either substance alone. Authors.