Modelling of ultraviolet light inactivation kinetics of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, Clostridium difficile spores and murine norovirus on fomite surfaces.

Quantitative data on the doses needed to inactivate micro-organisms on fomites are not available for ultraviolet applications. The goal of this study was to determine the doses of UV light needed to reduce bacteria and murine norovirus (MNV) on hard surface fomites through experimentation and to identify appropriate models for predicting targeted levels of reduction. Stainless steel and Formica laminate coupons were selected as they are common surfaces found in healthcare settings. Test organisms included methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Clostridium difficile and MNV. The fomites were inoculated with 105 -107 bacteria or virus and exposed to a range of UV doses. The order of resistance to UV irradiation was virus, bacterial spore and vegetative cell. The best fitting inactivation curves suggested nonlinear responses to increasing doses after a 3-4 log reduction in the test organisms. The average UV doses required for a 3 log reduction in the C. difficile, MRSA and VRE were 16 000, 6164 and 11 228 (mJ-s cm-2 ) for stainless steel, respectively, and 16 000, 11 727 and 12 441 (mJ-s cm-2 ) for Formica laminate, respectively. Higher UV light doses are required to inactivate bacteria and viruses on hard surfaces than in suspension. Greater doses are needed to inactivate bacterial spores and MNV compared to vegetative bacteria. Quantitative data and models on UV light doses needed to inactivate bacteria and MNV on hard surfaces are now available. The generalizable results of this study can be used to estimate required UV dosages to achieve targeted levels of inactivation based on estimated levels of contamination or to support quantitative microbial risk assessments.

Mitchell JB ，Sifuentes LY ，Wissler A ，Abd-Elmaksoud S ，Lopez GU ，Gerba CP ... -  《-》

Effect of UV-C light or hydrogen peroxide wipes on the inactivation of methicillin-resistant Staphylococcus aureus, Clostridium difficile spores and norovirus surrogate.

The current study aimed to assess the potential of a new high dose ultraviolet (UV) disinfection device to inactivate methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile and a norovirus surrogate on handheld mobile devices, and to compare the efficacy of the UV-C device to hydrogen peroxide disinfection wipes. Suspensions of MRSA, C. difficile spores and a surrogate for norovirus (MS2) were inoculated onto glass or plastic coupons, with or without organic contamination and were exposed to continuous UV-C light for 15-60 s (165-646 mJ cm-2 ) in a self-contained UV-C chamber or treated with hydrogen peroxide wipes. Increasing the UV-C dose from 310 to 650 mJ cm-2 did not result in greater levels of inactivation. UV-C light inactivated all three micro-organisms, in the absence of organic contamination, by >2·9 log. Treatment of MRSA, C. difficile spores or MS2, in the presence of organic contamination, with UV-C light (310-646 mJ cm-2 ) resulted in 2·3-3·7 log reductions. Treatment of MRSA with UV-C light provided levels of inactivation comparable to treatment with hydrogen peroxide wipes used following the manufacturer's instructions. UV-C light and hydrogen peroxide wipes had strong antimicrobial activity against MRSA, C. difficile spores and a norovirus surrogate, in the presence or absence of organic contamination. Chemical disinfection wipes are widely used in healthcare facilities, but they are not recommended for use on handheld mobile devices which may harbour pathogenic micro-organisms. The powerful bactericidal, sporicidal and virucidal activity of this high dose UV-C light device, shows that this technology is a promising alternative to chemical disinfectants, particularly for control of MRSA.

Wallace RL ，Ouellette M ，Jean J 《-》

Evaluation of a pulsed xenon ultraviolet disinfection system for reduction of healthcare-associated pathogens in hospital rooms.

Nerandzic MM ，Thota P ，Sankar C T ，Jencson A ，Cadnum JL ，Ray AJ ，Salata RA ，Watkins RR ，Donskey CJ ... -  《-》

Evaluation of a hand-held far-ultraviolet radiation device for decontamination of Clostridium difficile and other healthcare-associated pathogens.

Nerandzic MM ，Cadnum JL ，Eckart KE ，Donskey CJ ... -  《BMC INFECTIOUS DISEASES》

A comparison of the efficacy of multiple ultraviolet light room decontamination devices in a radiology procedure room.

Cadnum JL ，Jencson AL ，Gestrich SA ，Livingston SH ，Karaman BA ，Benner KJ ，Wilson BM ，Donskey CJ ... -  《-》