Effectiveness of automated ultraviolet-C light for decontamination of textiles inoculated with Enterococcus faecium

doi:10.1016/j.jhin.2017.07.034

Journal of Hospital Infection

Volume 98, Issue 1, January 2018, Pages 102-104

https://doi.org/10.1016/j.jhin.2017.07.034 Get rights and content

Summary

Healthcare textiles are increasingly recognized as potential vehicles for transmission of hospital-acquired infections. This study tested the ability of an automated ultraviolet-C (UV-C) room disinfection device (Tru-D Smart UV-C) to decontaminate textiles inoculated with Enterococcus faecium in a clinical setting. Contaminated polycotton (50/50 polyester/cotton) swatches were distributed to predefined locations in a ward room and exposed to UV-C light. UV-C decontamination reduced E. faecium counts by a mean log₁₀ reduction factor of 1.37 (all P = 0.005, Wilcoxon signed rank test). UV-C decontamination may be a feasible adjunctive measure to conventional laundering to preserve the cleanliness of healthcare textiles in ward rooms.

Introduction

Healthcare textiles are increasingly recognized as potential vehicles for the transmission of hospital-acquired infections [1]. It has been estimated that half of all surfaces in the patient's environment are soft [2], and in one study, 92% of hospital privacy curtains became contaminated with pathogens within one week [1]. Meticillin-resistant Staphylococcus aureus (MRSA) can survive on fabrics for more than three weeks, and there is evidence that vancomycin-resistant enterococci can survive for at least seven weeks [3]. Conventional laundering of hospital textiles can be costly and time-consuming, and may not be readily available at all times [4]. Consequently, it may not be possible to change hospital textiles as frequently as might be desirable. There are, however, few options that provide the same degree of textile decontamination as conventional laundering.

Germicidal ultraviolet-C (UV-C, 254 nm wavelength) light kills bacteria through pyrimidine dimerization [5]. Originally designed for terminal room decontamination, Tru-D (Tru-D SmartUVC, Lumalier Corporation, Memphis, TN, USA) is a mobile unit that emits UV-C light and permits quick, automated, disinfection of hospital rooms. It has been shown to be effective in the eradication of various pathogens, including multi-drug-resistant strains, from hard surfaces [5], [6], [7], [8], [9].

The purpose of this study was to evaluate the efficacy of automated UV-C decontamination on Enterococcus faecium in fabrics in a clinical setting. To ensure realistic trial conditions, an unoccupied intermediate care ward room at Uppsala Burn Centre was used for decontamination experiments. Samples were distributed to locations that are usually in frequent contact with the patient, bodily fluids or both, and where contamination of healthcare textiles such as bed linen, patient gowns or privacy curtains would be likely to occur. E. faecium was chosen as the test pathogen because it could be used safely within the burn centre, it is able to withstand drying on fabrics, and it has been shown to be relatively impervious to influences from its environment.

Section snippets

Fabrics

Bleached sterile swatches measuring 10 × 10 cm that originated from the clothes of hospital staff were used as the carrier material. Fabrics were a blend of 50% cotton and 50% polyester (polycotton), a common blend of fabrics in healthcare textiles, including bed linen, patient gowns and privacy curtains. Samples were used once and discarded after the experiment.

Inocula and contamination of swatches

A single colony of E. faecium (NCTC7171/CCUG33573) from an overnight culture was incubated in brain heart infusion broth (BBL, BD

Results

The median time required for decontamination was 111 (range 108–165) min, and UV-C decontamination reduced the bacterial count, on average, by a log₁₀ reduction factor of 1.37. The greatest reduction was seen in the samples placed on the floor adjoining the bed (log₁₀ reduction factor −1.97), while the smallest reduction was seen in samples placed in the cupboard (log₁₀ reduction factor −0.57). In all samples, the reduction was significant. Detailed data are provided in Table I.

Discussion

To the best of the authors' knowledge, this is the first study to evaluate the efficacy of the Tru-D device on fabrics inoculated with E. faecium in a clinical setting.

Mahida et al. reported a log₁₀ reduction factor of 4.0 of enterococci inoculated on Petri dishes, equalling eradication of 99.99% of viable bacteria after application of the sporicidal 22,000 μWs/m² reflective dose [5]. In the present study, the maximum reduction of E. faecium was considerably lower (log₁₀ reduction factor of

Acknowledgements

The authors wish to thank Mary Evans for language editing the manuscript.

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Citation Excerpt :
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Our primary aim was to investigate, using a commercial radiometer, the ultraviolet C (UVC) dose received in different areas in a burn ICU ward room after an automated UVC decontamination. The secondary aim was to validate a disposable UVC-dose indicator with the radiometer readings.
Disposable indicators and an electronic radiometer were positioned in ten different positions in a burn ICU room. The room was decontaminated using the Tru-D™-UVC device. Colour changes of the disposable indicators and radiometer readings were noted and compared. Experiment was repeated 10 times.
The UVC radiation received in different areas varied between 15.9 mJ/cm² and 1068 mJ/cm² (median 266 mJ/cm²). Surfaces, at shorter distances and in the direct line of sight of the UVC device showed statistically significant higher UVC doses than surfaces in the shadow of equipment (p = 0.019). The UVC-dose indicator’s colour change corresponded with the commercially radiometer readings.
The amount of UVC radiation that is received in surfaces depends on their locations in the room (ie distance from the UVC emitter) and whether any objects shadow the light. In this study we suggest that quality controls should be used to assure that enough UVC radiation reaches all surfaces.
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A number of studies have also investigated transmission dynamics between shoe soles or floor surfaces and patient colonization, with most studies demonstrating colonization potential via aerosolization, direct contact or indirect methods [5–8]. Ultraviolet C (UVC) devices are used in hospitals to decontaminate the hospital environment [9,10]. Recently, a shoe sole UVC decontamination device has become available (HealthySole Plus, Healthy Sole, Inc, Minden, NV, USA).
An ultraviolet C (UVC) decontamination device that delivers germicidal UVC radiation to the soles of shoes has become available recently.
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^†: Both authors contributed equally to this paper.

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Short reportEffectiveness of automated ultraviolet-C light for decontamination of textiles inoculated with Enterococcus faecium

Summary

Introduction

Section snippets

Fabrics

Inocula and contamination of swatches

Results

Discussion

Acknowledgements

J Hosp Infect

J Hosp Infect

Can ultraviolet light C decrease the environmental burden of antimicrobial-resistant and -sensitive bacteria on textiles?

Vet Dermatol

Survival of enterococci and staphylococci on hospital fabrics and plastic

J Clin Microbiol

Level of decontamination after washing textiles at 60°C or 70°C followed by tumble drying

Infect Ecol Epidemiol

Short report
Effectiveness of automated ultraviolet-C light for decontamination of textiles inoculated with Enterococcus faecium