ABSTRACT

This disinfecting actions of three disinfectants (ethanol, bleach and phenolics on two selected organisms, Staphylococcus aureus and Pseudornonas aeruginosa were studied. The bacterial species employed for the study were pure isolates from the stock cultures of Microbiology laboratory, Michael Okpara University of Agriculture Umudike. Their identities were confirmed using a three-way analysis including cultural examination, microscopic examination and biochemical tests. The methods used for the investigation included the Disc Diffusion method and Kirby Bauer Diffusion Assay Well method. Different concentrations of bleach (1%, 2%, 3%, 4% and 6%) were used on both test organisms. Also (50%, 60%, 80%, 85% and 95%) of ethanol as well as (5%, 10%, 20%, 25%, and 30%) phenolics were used. Differences in concentrations tested were because the original concentrations of the disinfectants differ. After 24 hours of incubation at 3 7°C, the results showed that all the disinfectants inhibited the growth of the test organisms in their concentrated forms with the exception of ethanol which was effective at concentrations above 90%. In both methods, the diameters of the zones of inhibition were measured using a ruler calibrated in millimeters, using different concentrations, and their efficacies varied. In the Disc Diffusion method, 30% Phenolics was found to exhibit the highest activity on Staphylococcus aureus with the diameter of inhibition of 37mm while 1% bleach showed the least with the diameter of inhibition of 0mm, while using the Kirby Bauer Assay Well Method, 30% Phenolics exhibited the highest activities on Pseudomonas aeruginosa with the diameter of inhibition of 31mm while 95% Ethanol and 1% Bleach exhibited the least inhibition activities.