Effect of excess alkali on the tuberculocidal activity of phenates.

Ortenzio, Opalsky, and Stuart (Appl. Microbiol. 9:562, 1961) presented data showing that phenates may kill bacteria in a different manner than the parent phenols, and that excess uncombined alkali in phenolic-type formulations has a much greater inactivating effect for gram-positive cocci than for gram-negative enteric bacteria. This study is a continuation of these investigations to determine the magnitude of the inactivating effect of excess uncombined alkali in phenolic preparations on the germicidal activity against Mycobacterium tuberculosis. was M. tuberculosis var. bovis (BCG). Solutions (1%) of sodium o-phenylphenate and sodium o-benzyl-p-chlorophenate were prepared from the pure phenols by use of stoichiometric amounts of sodium hydroxide. Excess alkali was added to provide solutions of the pure phenates plus 0.5, 1.0, 2.0, and 3.0% excess alkali based on the weight of the phenate. These solutions were tested as described above (Table 1). The results show that a 1% solution of sodium o-phenylphenate in the absence of excess sodium hydroxide is an effective tuberculocidal agent.