Evaluation of the efficacy of bleach routinely used in health facilities against Mycobacterium tuberculosis isolates in Ethiopia
Pan African Medical Journal
Bahir Dar University, College of Medicine and Health Sciences, Department of Medical Microbiology, Immunology and Parasitology, Bahir Dar, Ethiopia; Bahir Dar Regional Health Research Laboratory Center, Department of Regional Mycobacteriology Laboratory, Bahir Dar, Ethiopia; Bahir Dar University, College of Medicine and Health Sciences, School of Public Health, Ethiopia; Institute of Medical Microbiology and Epidemiology of Infectious Diseases, University of Leipzig, Germany
Introduction: In Ethiopia, the most widely used disinfectant is 5% Hypochlorites. However, Ethiopian national health safety and infection prevention guideline recommendation on the use of bleach is not consistent and varying from 0.1%-4%. The purpose of this study was therefore to assess the effective time-concentration relationship of sodium hypochlorite against Mycobacterium tuberculosis complex isolates in the absence of any organic load. Methods: This experimental study was conducted in Bahir Dar Regional laboratory from February-June 2013. Test suspensions of 1.5 X 108 CFU/ml prepared using normal saline containing 0.5% tween 80. From 5% stock, 0.1%, 0.5%, 1% and 2% bleach was prepared. A 1ml of test strain suspension and 1ml of bleach mixed and allowed to stand until the specified time achieved, neutralized by 48 ml phosphate buffer. 100µl from the diluted sediment were spread on two L-J mediums and incubated at 37°C for 8 weeks. Results: When 0. 1% bleach was used for 10 min, majority 11/20 of isolates showed 3 x 103 CFU/ml growth (ME=4.4) which was inefficient. However, when the time increased, the log10 reduction was acceptable, ME >5 and it was effective. The bleach solution containing 0.5% and above was effective in all respective times. In this study, there is no difference observed in the tuberculocidal activity of bleach against resistant and sensitive strains. Conclusion: Our study showed that in the absence of any organic load, 0.1% bleaches over 15 min and 0.5 % bleaches over 10 min was found to be tuberculocidal. © Daniel Mekonnen et al.
bleaching agent; hypochlorite sodium; Article; bacterial growth; bacterial strain; bactericidal activity; bacterium isolate; controlled study; disinfection; dose time effect relation; Ethiopia; growth inhibition; health care facility; infection prevention; instrument sterilization; laboratory; Mycobacterium tuberculosis; nonhuman; pH; temperature sensitivity; water temperature