Background: Recent evidence suggests that the contaminated hospital environment is an important source for transmission of epidemiologically -important pathogens(EIP) such as MRSA and VRE. An overhead light fixture technology, which continuously and safely disinfects the environment was assessed to determine the effectiveness for the reduction of EIP. This technology creates a narrow bandwidth of high-intensity visible blue light with a peak output of 405nm that generates reactive oxygen species and kills microorganisms.
Methods: The new technology was evaluated in two different clinical configurations (White Disinfection Mode and Supplemental Blue-Disinfection Mode). In Phase 1, 2-2x2 blended-white, ceiling-mounted fixtures were used which provided both disinfection and ambient white illumination for use in normal clinical conditions in an occupied room (surface irradiance~0.12 mW/cm2-0.16 mW/cm2 measured at the pathogen location). In Phase 2, a higher-level of disinfection was studied with the addition of a 2x4 overhead. This fixture emits only disinfecting (blue) light (surface irradiance=0.34-0.44 mW/cm2). The four test organisms were C. difficile spores (BI), MRSA (ATCC 43300), VRE (ATCC 51299), and MDR-A. baumannii (MDRA). Formica test surfaces were inoculated with 100-300 CFUs of test organisms. Once dry, triplicate samples were collected with Rodac plates containing DE Neutralizing Agar at times 0, 1hr, 3hr, 5hr, 6hr, 7hr, 24hr, 48hr, 72hr and 96hr and then appropriately incubated. To accommodate the natural die-off of vegetative bacteria, a control test surface (Formica) was placed in an adjacent area but not exposed to the light disinfection.
Results: These results demonstrated that the 405nm light inactivated three vegetative bacteria (MRSA, VRE, MDRA) on surfaces with contact times of 1-96hr. Statistical differences (p<0.05) were observed using blue light for VRE at 24 hr, for MRSA at 3-7hr, for MDRA at 5-24hr, and for C. difficile spores at 5hr and 72hr. The inactivation was more significant when the surface irradiance was increased by adding the blue light.
Conclusion: This technology could be considered for several healthcare decontamination applications (e.g., OR).
Unrestricted gift for resaerch
M. Gergen, None
E. Sickbert-Bennett, None
D. Sexton, None
D. Anderson, None
D. J. Weber, None