Abstract

The present study assessed the microbiological quality and efficacy of two common disinfectants (Jik and Lysol) used in a
hospital laboratory. Sterility test using Nutrient Agar and Sabour Dextrose Agar plates incubated at 37°C and 25°C,
respectively, were employed to detect the present of potential bacterial and fungal contaminants in 3 new batches of stock
disinfectants. Swabs of work-bench surfaces designated as Site 1, 2 and 3 were collected in triplicate at the end of each
business day (i.e, before disinfection) and also after disinfection with 30% Jik and 2.5% Lysol dilution and cultured in tubes
containing 3 ml of Tryptic Soy Broth medium and 0.1 mL Neutralizer. Surface viable count was carried out to determine the
bacterial population density of three sites pre-disinfection and post-disinfection. Colonies of bacteria were identified by Gramstain,
motility test and routine biochemical tests. The efficacy of the disinfectants against each bacterial isolate at 10 min
contact time was determined using the quantitative suspension test. The killing rate of the disinfectants was expressed by
plotting the logarithms of surviving cells (CFU/mL) against exposure time (min) of the disinfectant. The outcome of the study
showed that the microbiological quality of the two disinfectants tested was satisfactory. Bacterial distribution pre-disinfection
include: Staphylococcus epidermidis, Enterococcus aerogenes, Proteus mirabilis, Bacillus subtilis, Pseudomonas aeruginosa
and Klebsiellia pneumoniae; while only B. subtilis, P. aeruginosa and K. pneumoniae were recovered post-disinfection. Lysol
proved to be more potent than Jik at the dilution and contact time tested with a log reduction of bacterial population ?5. S.
epidermidis, E. aerogenes and P. mirabilis were completely killed by the two disinfectants within the 10 minutes contact time.
While, a population density of 1-2 log CFU/ml of B. subtilis, P. aeruginosa and K. pneumoniae still survived after 10 min
exposure to Lysol and Jik. The outcome of this study further strengthening earlier works and underscored the need to
periodically assess the microbiological quality and efficacy of disinfectants routinely supplied to the laboratory to ensure
proper control of infections by using right disinfectant in right concentration for a right contact time.