MINIMUM INHIBITORY CONCENTRATION OF TWO COMMONLY USED DISINFECTANT AGAINST CLINICAL BACTERIAL ISOLATES IN BENIN CITY, NIGERIA

ABSTRACT

The Minimum inhibitory concentration (Mic) of two disinfectants (sodium hypochlorite and chloroxylenol) to the clinical isolates was determined using macro broth dilution technique. A total of 80 clinical bacterial isolate was employed in this study comprising 20 each of Staphylococcus aureus, Pseudomonas aeruginosa. Klebsiella pneumoniae and Escherichia coli obtained from clinical specimen in the medical microbiology laboratory of the University of Benin Teaching Hospital(UBTH). The study showed significant differences between the disinfectant sodium hypochlorite and test organism which were P for Staphylococcus aureus versus Klebsiella pneumoniae and Staphylococcus aureus versus Pseudomonas aeruginosa and P for Escherichia coli versus Pseudomonas aeruginosa and Klesiella pneumoniae versus Pseudomonas aeruginosa. For the disinfectant sodium hypochlorite, various MIC was obtained with the highest MIC seen in Klebsiella pneumoniae (1.13 ± 0.43 mg/ml), and the lowest MIC seen in Pseudomonas aeruginosa (0.39±0.22 mg/ml). For chloroxylenol, a uniform MIC (1250±0 µg/ml) was obtained for the test organism Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa while a lower MIC (625±0 µg/ml) was obtained for Klebsiella pneumoniae. This study revealed varying MIC for the disinfectants used as disinfecting agents from different hospital wards. The highest and lowest MIC was obtained from isolates recovered from maternity ward (1.25±0.88mg/ml) and surgical ward(0.57±0.37mg/ml) for sodium hypochlorite while in respect to chloroxylenol, the highest and lowest MIC was obtained from isolate recovered from medical ward(1171±220.97µg/ml) and Neuro ward (937.50±360.84µg/ml). Chloroxylenol was not effective against the tested isolates. Proper use of disinfectant is advocated