THE EFFECT OF pH ON THE ANTIMICROBIAL ACTIVITY OF PARA-AMINOTOLUENE SULFONAMIDE

¹ Department of Research and Biochemistry, Loyola University School of Dentistry, Chicago, Ill.

The antibacterial activity of PATS has been investigated in environments of differing pH. Under the experimental conditions described, the following factors become apparent.

1. As environmental pH changes from 4 to 6, the antibacterial activity of PATS decreases markedly.

2. At pH 6 to 7, there is marked lack of bactericidal activity, although bacteriostasis occurs at PATS concentrations of 3 per cent or less.

3. At pH 7.4 to 8, there is maximum bactericidal activity; the maximum bactericidal concentration being 0.10 per cent.

4. Maximum effectiveness of PATS appears to be associated with formation of the free base which presumably has greater penetrability and hence exhibits greater activity.

Although clinical situations cannot be compared to the conditions described, the implication is clear that the pH of a root canal, undergoing treatment with PATS, may play an important role in determining success of the treatment.