Research
Bacterial growth of a contaminated surface after decontamination with V-Go™ UV light sanitizer on various surfaces
Location of testing: Veterinary Medicine Teaching Hospital Clinical Lab
Performed by: Barbara Bryne PhD, DVM UC Davis School of Medicine and Christian Sandrock MD, MPH UC Davis School of Medicine
Date: March 11, 2021
Methods: Established strains of Escherichia coli (ATCC 25922) were incubated at 35C in a brain heart infusion broth for 2 hours and adjusted to a 0.5 McFarland Standard in 0.85% saline using a nephelometer. Serial dilutions were made in saline to approximated concentrations 10^6 colony forming units (CFU) per mL. Final concentrations were confirmed by plating on 5% sheep blood agar and tryptic soy agar contact plates with a final concentration of E. coli 4.0 X 10^5 CFU/mL in the highest concentration (10^6). 10 uL of each strain was applied to a 1x1 cm swatch of sterile cotton, thick surgical towel, plastic, and glass. UV light in a UVA/UVC combination (UV-A 395 nm and UV-C at 275nm) and UVC (UV-C at 275nm) were applied via handheld V-go device at a height of 1.5 inches to each swatch at time intervals of 1 and 5 seconds with an estimated irradiance of 3000 uW/cm2. Controls of each strain and concentration was applied to swatches at the same concentrations and UV exposure. Both controls and irradiated disks were immediately plated on tryptic soy agar with lecithin and incubated at 35C for 48 hours in 5% CO2 at which point growth was determined.
Results: After application of UV light by V-Go™ no growth was appreciated for E. coli after a 48-hour incubation. The controls had appropriate growth as outlined in Table 1
Conclusion: both UV-C and UVA/UVC combinations delivered by V-Go™ UV light sanitizer produced minima growth of E. coli when applied at a height of 1.5 inches for 1 and 5 seconds when compared to controls. The application of UVA/UVC combination at 5 seconds provided 100% killing on all surfaces. For this test, no statistically significant differences in CFU counts were seen between UVC/UVA and UVC treatments. Due to high absorption, surgical towel results should be repeated.
Bacterial growth of a contaminated surface after decontamination with V-Go™ UV light sanitizer
Location of testing: Veterinary Medicine Teaching Hospital Clinical Lab
Performed by: Barbara Bryne PhD, DVM UC Davis School of Medicine and Christian Sandrock MD, MPH UC Davis School of Medicine
Date: 11-25-2020
Methods: Established strains of Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC29213) were incubated at 35C in a brain heart infusion broth for 2 hours and adjusted to a 0.5 McFarland Standard in 0.85% saline using a nephelometer. Serial dilutions were made in saline to approximated concentrations 10^6, 10^4, and 10^3 colony forming units (CFU) per mL. Final concentrations were confirmed by plating on 5% sheep blood agar and tryptic soy agar contact plates with a final concentration of E. coli 3.8 X 10^5 CFU/mL and 9.0 X 10^4 CFU/mL for S. aureus in the highest concentration (10^6). 10 uL of each strain was applied to a 1.25 cm disc at each of the following approximated concentrations: 10^6, 10^4, and 10^3. UV light (UV-A 395 nm and UV-C at 275nm) was applied via handheld V-Go™ device at a height of 1.0-1.5 inches to each bacterial strain and concentration at time intervals of 1, 3 and 5 seconds with an estimated irradiance of 3000 uW/cm2. Controls of each strain and concentration was applied to discs at the same concentrations. Both controls and irradiated disks were immediately plated on tryptic soy agar with lecithin and incubated at 35C for 48 hours in 5% CO2 at which point growth was determined.
Results: After application of UV light by V-Go™ no growth was appreciated for both E. coli and S. aureus after a 48-hour incubation. The controls had appropriate growth as outlined in Table 1.
Conclusion: UV light (UVC and UVA) delivered by V-Go™ produced no appreciable growth of E. coli and S. aureus when applied at a height of 1.0 - 1.5 inches for 1, 3 and 5 seconds when compared to controls.
