METHENAMINE AND ITS SALTS AS URINARY-TRACT ANTISEPTICS - VARIABLES AFFECTING ANTIBACTERIAL ACTIVITY OF FORMALDEHYDE, MANDELIC-ACID, AND HIPPURIC ACID INVITRO

  • 1 January 1977
    • journal article
    • research article
    • Vol. 14  (4) , 287-291
Abstract
The activities of formaldehyde and of mandelic and hippuric acids, alone and in combination, were tested against some 300 strains of bacteria typical of those causing urinary tract infections. In a chemically defined medium, which resembles urine in many respects, formaldehyde had a mean minimal inhibitory concentration of 13 .mu.g/ml. Activity was several-fold lower in media (nutrient agar and tryptic soy agar) that contained significant amounts of protein. The activity of formaldehyde is virtually unaffected by pH in the range of 5-8. Mandelic and hippuric acids (2 mg/ml) have limited antimicrobial activity at acid pH values only. The combination of formaldehyde with mandelic acid (2 mg/ml) was additive, most markedly at pH 5; the formaldehyde-hippuric acid combination did not appear to be additive. At pH values between 5-6, an antibacterial concentration of formaldehyde will apparently be generated from methenamine within approximately 1 h after being excreted into the urine.