Germicidal UV Sensitivity of Bacteria in Aerosols and on Contaminated Surfaces

Abstract

We compared the UV sensitivity of Bacillus atrophaeus (a surrogate for B. anthracis), Pantoea agglomerans (a bacterial simulant frequently used in biodefense studies), and Yersinia ruckeri (a surrogate for Yersinia pestis) either airborne or deposited on a semisolid (wet) agar surface. Bacterial vegetative cells were aerosolized into an exposure chamber and exposed for various lengths of time to an ultraviolet (UV) light source emitting at 254 nanometer (nm) (in the UVC region also known as UVGI). Aerosols were collected onto gelatin filters, which were dissolved, diluted, plated, and incubated to enumerate colony formation. In darkness (with the UV light

Aerobiological Stabilities of Different Species of Gram-Negative Bacteria, Including Well-Known Biothreat Simulants, in Single-Cell Particles and Cell Clusters of Different Compositions

“…Knowledge about the aerobiological stability of biothreat agents therefore is fundamental to correctly assess the potential health implications following an aerosol attack involving inhalation exposure to biothreat agents (11). In response to a range of technical and practical challenges associated with suspending microorganisms as an aerosol for extended periods of time under controlled experimental conditions, several practical approaches have been developed to study aerobiological stability of microorganisms, including stirred-settling aerosol chambers (12), rotating aerosol drums (13), and microthread-based suspension techniques (14).…”

Decontamination of Bioaerosols within Engineering Tolerances of Aircraft Materials

“…One potential problem with UV is that the light waves must make contact with the actual organism, so any organic matter present provides protection (King et al, 2011 (Scheffrahn, 2005).…”

“…Several test chambers have been designed to aerosolize and then deposit biological simulants onto some type of coupon for further testing (Baron et al, 2007;Baron et al, 2008;Brown et al, 2007aBrown et al, , 2007bBrown et al, , 2007cButtner et al, 2004;Chen et al, 1999;Edmonds et al 2009;Estill et al, 2009;Kesavan, 2008;King et al, 2011;Farnsworth et al, 2006;;Feather and Chen, 234 2003; Byrne et al, 1995;Lai et al, 2002;Kenny et al, 1999;Koch et al, 1999;Lewandowski et al, 2010;Marple and Rubow, 1983;Park et al, 2009;Thatcher and Nazaroff, 1997). With few exceptions (King, 2010), these chambers were constructed to evaluate deposition or swipe sampling and have not been used to evaluate the effectiveness of decontamination methods.…”

“…Studies have been completed using five-20µL drops of 10 7 stock of BG spores, allowing the coupons to air dry a minimum of 3 hours or until all the liquid was completely evaporated (Edmonds et al, 2009). Ten-fold dilutions of the bacterial suspensions were completed with 100 μL of 165 suspension containing the specific species of bacteria under study which was spread onto trypticase TM soy nutrient agar in plastic Petri dishes (King et al, 2011). Spreading onto the agar plate is another consideration.…”

Student absenteeism and the comparisons of two sampling procedures for culturable bioaerosol measurement in classrooms with and without upper room ultraviolet germicidal irradiation devices

“…10 UV germicidal irradiation disinfects specific bioaerosols in laboratory studies with multiple research studies demonstrating that upper room air UVGI can remove or inactivate bacterial bioaerosols in both chamber and one-pass tests. [11][12][13][14][15][16] However, limited studies have been conducted with fungal spore challenges for upper room UVGI and air cleaners containing UV lamps, so as a result the impact of UVGI on many fungal spores is not clear. 12,17 The effectiveness of upper room UVGI systems has been shown to be affected by environmental parameters, such as room airflow pattern, air mixing and many other factors.…”