Efficacy of Commonly Used Sterilants and Disinfectants Against Bacterial Contaminants in a Clinical Laboratory Setting in Kenya

Abstract

Nosocomial infections, spread via hands of patients or health care givers or contaminated surfaces / equipment are a major concern in healthcare settings and contribute to increase in morbidity, mortality, hospital stay and medical expenses. However, there is limited knowledge regarding efficacy of common disinfectants used in healthcare settings in Kenya. This study undertaken at Moi Teaching and Referral Hospital, Uasin Gishu County, Kenya, sought to determine the diversity of microbial contaminants in clinical laboratory settings, the range and use of sterilants /disinfectants, establish their efficacy and compare efficacy values between BSAC standard and MTRH methods. A total of 200 swabs were collected from floor, walls, benchtops, and equipment and processed using standard procedures. Disc diffusion method was used to determine and compare efficacy of sterilants /disinfectants against bacterial isolates. Control strains were Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, S. aureus ATCC 29213 and E. faecalis ATCC 29212. The commonly used sterilants were alcohol (39.4%), iodophor (13.3%), hypochlorite (43.3%), hydrogen peroxide and glutaraldehyde (1.28%) each respectively. The predominant bacterial contaminants obtained from laboratory walls (31.5%, workbench (33%), floor (32%) and equipment (2.5%) were Escherichia coli (34.5%), Klebsiella pneumonia (18.5%), Pseudomonas aeruginosa (9.0%), Proteus mirabilis (3.5%), and Salmonella typhi (7.0%), coliforms (19.0%), Staphylococcus aureus and Streptococcus pneumonia (2.0%) each. Among the isolates, Escherichia coli and Proteus mirabilis showed 100% resistance each to iodophor. However, E. coli, K. pneumoniae and P. mirabilis all sensitive (100%) to alcohol followed by P. aeruginosa (93%). The sterilant / disinfectant efficacy profile of microbe isolates determined by BSAC method showed high resistance (< 90%) to most sterilants / disinfectants while MTRH method had resistance ton iodophors but most isolates were sensitive to alcohol. Comparison of BSAC and MTRH showed 100% agreement for Iodophors but variations for alcohol, hypochlorite, and hydrogen peroxide. This depicts a need to perform tests and review concentrations in order to validate efficacy and improve performance of sterilant / disinfectants at the hospital laboratory. The study recommends quality control and regular testing of sterilants/disinfectants as an integral component of infection control to prevent nosocomial infections and evolution of resistant strains.