The anti microbial activities of three commonly 
used disinfectants Septol, Dettol and Z-germicides against 
Escherichia coli, Staphylococcus aureus and Candida 
albicans were investigated. Their efficacies were determined 
using the agar diffusion method at different concentrations of 
the test disinfectants and their potency was tested against a 
standard (phenol) by using phenol coefficient tests. The use 
of Septol on E.coli and S.aureus showed weak bactericidal 
efficacy with a zone of inhibition of 30mm and 29mm at 
100% concentrations as compared to the others, even in their 
use in dilutions, although it possesses a high efficacy against 
C.albicans with a zone of inhibition of 75mm. Dettol and Z
germicides had equal inhibitory effects of 45mm on E.coli 
and S.aureus at 100% concentrations but Dettol was more 
effective, as compared to Z-germicides, although S.aureus 
was observed to be the most susceptible to Z-germicides 
when used in higher concentrations. It was observed that as 
the concentration reduces the susceptibility rates of the test 
organisms increases. The potency of the disinfectants against 
a standard disinfectant (phenol) showed that they were all 
more effective than phenol with Dettol being the most potent 
disinfectant as compared to both Z-germicide and Septol. To 
ensure disinfectants efficacy, tests should be carried out on 
new disinfectant products and also further studies should be 
carried out about disinfectants.

Keywords: Disinfectants; Pathogens; Efficacy