An investigation of the bactericidal and fungicidal effects of certain disinfectants by use of a capacity test

Abstract

The bactericidal and fungicidal effects of five disinfectants and one combination of two disinfectants were tested using a modified Kelsey-Sykes method in which living microorganisms suspended in a sterilized yeast suspension («dirtyå conditions) and in sterile distilled water («cleanå conditions) were added to the disinfectants in three stages. Six bacteria and two fungal organisms were employed as test microbes.

Results showed that formaldehyde was virtually inactive at the dilution tested (1/50), whereas phenol and the combination propylene-phenoxetol +benzalkonium chloride were moderately effective, the latter compound being better. Glutaraldehyde was manifestly the most effective of the disinfectants tested, followed by tricresol. At a 1/50 dilution, chloramine proved to have a surprisingly strong fungicidal effect on Candida albicans and Aspergillus fumigatus under «dirtyå conditions, whereas the same fungal organisms proved rather resistant to chloramine under «cleanå conditions. The same was demonstrated–though less markedly—when higher dilutions o chrloramine were used. The search for an explanation is still in progress. At relatively high dilutions, chloramine also proved effective against most of the test bacteria, especially under «cleanå conditions. It is recommended that the yeast suspension of chloramine against fungal strains under «dirtyå conditions.