Investigation on Potential ESKAPE Surrogates for 222 and 254 nm Irradiation Experiments

Abstract

BackgroundDue to the increase in multidrug-resistant pathogens, it is important to investigate further antimicrobial options. In order not to have to work directly with pathogens, the investigation of possible surrogates is an important aspect. It is examined how suitable possible surrogate candidates for ESKAPE pathogens are for UVC applications. In addition, the inactivation sensitivities to 222 and 254 nm radiation are compared in relation.MethodsNon-pathogenic members (Enterococcus mundtii, Staphylococcus carnosus, Acinetobacter kookii, Pseudomonas fluorescens and Escherichia coli) of genera of ESKAPE strains were photoinactivated in PBS with irradiation wavelengths of 222 and 254 nm (no non-pathogenic Klebsiella was available). Log reduction doses were determined and compared to published photoinactivation results on ESKAPE pathogens. It was assumed that non-pathogenic bacteria could be designated as surrogates for one wavelength and one ESKAPE strain, if the doses were between the 25 and 75% quantiles of published log reduction dose of the corresponding pathogen.ResultsFor all non-pathogen relatives (except A. kookii), higher average log reduction doses were required for irradiation at 222 nm than at 254 nm. Comparison by boxplot revealed that five of eight determined log reduction doses of the possible surrogates were within the 25 and 75% quantiles of the data for ESKAPE pathogens. The measured log reduction dose for non-pathogenic E. coli was above the 75% quantile at 222 nm, and the log reduction dose for S. carnosus was below the 25% quantile at 254 nm.ConclusionFor more than half of the studied cases, the examined ESKAPE relatives in this study can be applied as surrogates for ESKAPE pathogens. Because of lack of data, no clear statement could be made for Enterococcus faecalis at 222 nm and Acinetobacter baumannii at both wavelengths.

Photoinactivation of E. coli on Bagged Valerianella locusta and on Cichorium intybus var. foliosum with 222 and 254 nm

“…Irradiation experiments have also been carried out on fruits such as apricots for pathogens such as salmonella. This shows that the decontamination method used has also been successfully applied to other bacteria and foodstuffs, especially fruits [15]. If one compares the fact that higher doses were required for 222 nm than for 254 nm to achieve the same reduction with other research projects, the results are confirmed.…”

“…In contrast to the longer UV-C wavelengths, Far UV-C is less harmful to humans due to a lower penetration depth into the skin caused by absorption of the proteins of dead skin cells in the Stratum corneum [12]. For this reason, the question arises whether the irradiation of foods such as lamb's lettuce and chicory with UV-C and Far-UV-C radiation has a significant influence on the spread of pathogens, especially E. coli [13][14][15].…”

Disinfection of Transparent Screens by Side-Coupled UVA LED Radiation

“…One can raise the question whether the assumption made above-S. carnosus and S. saprophyticus having comparable log reduction doses-is realistic, or if the non-pathogenic S. carnosus is possibly much more sensitive to UVA than, e.g., the pathogens S. saprophyticus or S. aureus. So far, there are no suitable studies on S. saprophyticus or S. aureus in the UVA range, but there are investigations for bacteria in solutions in adjacent spectral ranges at 222 nm (UVC), 254 nm (UVC), 405 nm (visible light) and 450 nm (visible light) [22,23]. At 222 nm, S. carnosus and S. aureus are equally photosensitive, at 254 nm, S. carnosus is more susceptible, and at 405 and 450 nm, S. aureus is more sensitive.…”

Far-UVC Radiation for Disinfecting Hands or Gloves?

“…The log-reduction doses of most pathogens are well below these threshold values. For example, Staphylococcus aureus, Pseudomonas aeruginosa , and severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) in solution require 222 nm irradiation doses of 3.4, 2.0, and 1.2 mJ/cm 2 , respectively, for 90% reduction [ 20 , 21 ].…”