Lighting systems which incorporate antimicrobial 405nm light have been developed for safe continuous, environmental decontamination, with previous studies demonstrating efficacy for decontamination of frequently-touched surfaces around clinical areas. This study provides first direct evidence of the effects of this decontamination system for control of airborne contamination.

The study was conducted in a patient-occupied ICU isolation room over a 15-day period, with air samples collected at set times (before, during and after daily use of the decontamination system). Samples were also collected in the empty room prior to occupation. Environmental monitoring occurred every second day using a sieve-impactor sampler (500L air samples collected every 10-min over 2-hr (n=13)). Room activity was logged and bacterial contamination levels recorded as cfu/m3of air.

After 2-day use of the system, airborne contamination significantly decreased from a mean of 905.2 cfu/m3 to 48.8 cfu/m3 (P=0.002). Levels then remained fairly consistent over the remaining period of system use (48.8-189.8 cfu/m3) before significantly rising after the system was turned off for 3-days (P=0.001). Additional samples collected in isolation rooms without the decontamination system demonstrate that the levels of airborne bioburden tend to increase upon increasing patient stay, however low levels were maintained as patient occupation increased when the system was in use.

This study provides first direct evidence of the susceptibility of airborne bacteria to 405nm light within a clinical setting. This patient-safe technology has the potential to improve infection control strategies by complementing existing measures, which could reduce the number of infections arising from environmental sources.


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