Biocidal effect of UV-C light on environmental bacteria in a Neonatal Intensive Care Unit

Abstract

Abstract Background Germicidal irradiation with Ultra-Violet light type C (UV-C) (UV-C=200-280 nm) is used as a complement to hospital cleaning in health centers to disinfect air and surfaces, eliminating up to 99.9999% (-6 logarithms) of viruses and bacteria. Standard cleaning involves removing visible dirt with soap/detergent and water, while disinfection uses physical or chemical methods to eliminate pathogens, avoiding the risk of Healthcare Associated Infections (HAIs). Methods Experimental, prospective, analytical, single-blind study to compare the effectiveness of terminal disinfection with UV-C light on bacterial load (Colony-Forming Units: CFU) in the air and surfaces. Two scenarios were analyzed: a) Standard procedure (no intervention) and b) Continuous intervention with air disinfection. Cultures were taken from ambient surfaces and from 100 liters of air, before (pre-basal) and after cleaning/disinfection (minute 0 or baseline); in scenario b, the air disinfection lamp was also turned on at minutes 60, 120, 180, 240, 300 and 360. Descriptive statistics were used, a multilevel linear regression model was made for surfaces and then a second one for air. In addition, the flow of personel within the room was taken into account. Taking time and intervention with a repeated measures ANOVA model. Results 192 samples were taken for surface crops and 32 air samples. Conventional cleaning was adequate (with water and soap), however, disinfection with complementary UV-C light on surfaces decreased CFU to 0. Continuous air disinfection with UV-C light achieved the greatest reduction in CFU, sustained over time (scenario b). There is a direct correlation between the number of people in the room and the increase in CFU on surfaces and air (scenario a), with a significant reduction observed when disinfecting the air (scenario b). Conclusion UV-C light on air and surfaces is an effective and safe tool as a complement to hospital environmental cleaning. Its protocolized and sustained implementation, together with adequate hygiene measures and good clinical practices, contributes significantly to the reduction of environmental bacteria (on surfaces and in the air) and to the prevention of HAIs.