Effectiveness of commonly used high level disinfectants on bacteria responsible for hospital acquired infections in Sri Jayewardenepura General Hospital, Sri Lanka

Introduction: Hospital-acquired infections (HAIs) cause high morbidity and mortality in patients throughout the world. Nosocomial pathogens can be transmitted through contaminated instruments and surfaces. Disinfectants play a crucial role in preventing HAIs. This study focuses on two high level disinfectants designated ‘disinfectant 1’ which contains primarily peracetic acid and ‘disinfectant 2’ which contains primarily didecyldimethylammonium chloride.Objective: To determine the effectiveness of commonly used high level disinfectants on bacteria responsible for causing HAIs in Sri Jayewardenepura General Hospital, Sri Lanka (SJGH), on different surfaces.Method: Data of the Infection Prevention and Control (IPC) unit of SJGH was traced back to identify bacteria causing HAIs from 1st January to 31st July 2018. This experimental study was conducted for disinfectant 1 and 2 according to the quantitative carrier test (European Standard EN 14561:2006). Disinfectants were tested at three different concentrations on glass, stainless steel and rexine surfaces against the commonest three bacteria responsible for causing HAIs in SJGH.Results: Coliforms, Acinetobacter species and Staphylococcus aureus were the three most common bacteria responsible for causing HAIs in SGJH. Surgical site infections were the predominant type of HAI and Intensive Care Units (ICUs) were identified as having the highest prevalence of HAIs. Both high level disinfectants achieved a Microbicidal Effect (ME) value of 5 as per ‘clean disinfectants’ in manufacturer recommended dilutions and passed the test against Escherichia coli, Acinetobacter spp. and S. aureus under both clean and dirty condition on all three tested surfaces. However, bacterial colonies of all 3 test organisms were detected after both disinfectant 1 and 2 use . Effect of disinfectant 1 was poor in manufacturer recommended concentrations on glass, stainless steel and rexine surfaces. ME of disinfectant 2 was considerably higher when compared to disinfectant 1.Conclusion: Although the manufacturer stated test standard was achieved for both disinfectants, the presence of residual bacteria after high level disinfectant use on different surfaces is not acceptable.</p