References

Anderson DJ, Knelson LP, Moehring RW Implementation lessons learned from the benefits of enhanced terminal room (BETR) disinfection study: process and perceptions of enhanced disinfection with ultraviolet disinfection devices. Infect Control Hosp Epidemiol. 2018; 39:(2)157-163 https://doi.org/10.1017/ice.2017.268

Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. Lancet. 2022; 399:(10325)629-655 https://doi.org/10.1016/S0140-6736(21)02724-0

Armellino D, Walsh TJ, Petraitis V, Kowalski W. Assessment of focused multivector ultraviolet disinfection with shadowless delivery using 5-point multisided sampling of patient care equipment without manual-chemical disinfection. Am J Infect Control. 2019; 47:(4)409-414 https://doi.org/10.1016/j.ajic.2018.09.019

Bache SE, Maclean M, MacGregor SJ Clinical studies of the High-Intensity Narrow-Spectrum light Environmental Decontamination System (HINS-light EDS), for continuous disinfection in the burn unit inpatient and outpatient settings. Burns. 2012; 38:(1)69-76 https://doi.org/10.1016/j.burns.2011.03.008

Bache SE, Maclean M, Gettinby G, Anderson JG, MacGregor SJ, Taggart I. Universal decontamination of hospital surfaces in an occupied inpatient room with a continuous 405 nm light source. J Hosp Infect. 2018; 98:(1)67-73 https://doi.org/10.1016/j.jhin.2017.07.010

Beal A, Mahida N, Staniforth K, Vaughan N, Clarke M, Boswell T. First UK trial of Xenex PX-UV, an automated ultraviolet room decontamination device in a clinical haematology and bone marrow transplantation unit. J Hosp Infect. 2016; 93:(2)164-168 https://doi.org/10.1016/j.jhin.2016.03.016

Bhardwaj SK, Singh H, Deep A UVC-based photoinactivation as an efficient tool to control the transmission of coronaviruses. Sci Total Environ. 2021; 792 https://doi.org/10.1016/j.scitotenv.2021.148548

Birru M, Mengistu M, Siraj M Magnitude, diversity, and antibiograms of bacteria isolated from patient-care equipment and inanimate objects of selected wards in Arba Minch General Hospital, Southern Ethiopia. Res Rep Trop Med. 2021; 12:39-49 https://doi.org/10.2147/RRTM.S301215

Blanchard DM, Resendiz M, Lustik MB, West GF. Limited impact of an ultraviolet disinfection intervention on hygienic behaviors of nursing staff in a military hospital. Infect Control Hosp Epidemiol. 2022; 43:(6)797-799 https://doi.org/10.1017/ice.2021.118

Borji S, Rostamian M, Kadivarian S Prevalence of Clostridoides difficile contamination in the healthcare environment and instruments: a systematic review and meta-analysis. Germs. 2022; 12:(3)361-371

Brite J, McMillen T, Robilotti E Effectiveness of ultraviolet disinfection in reducing hospital-acquired Clostridium difficile and vancomycin-resistant Enterococcus on a bone marrow transplant unit. Infect Control Hosp Epidemiol. 2018; 39:(11)1301-1306 https://doi.org/10.1017/ice.2018.215

Cabral J, Ag R. Blue light disinfection in hospital infection control: advantages, drawbacks, and pitfalls. Antibiotics (Basel). 2019; 8:(2) https://doi.org/10.3390/antibiotics8020058

Casini B, Tuvo B, Cristina ML Evaluation of an ultraviolet C (UVC) light-emitting device for disinfection of high touch surfaces in hospital critical areas. Int J Environ Res Public Health. 2019; 16:(19) https://doi.org/10.3390/ijerph16193572

Casini B, Tuvo B, Scarpaci M Implementation of an environmental cleaning protocol in hospital critical areas using a UV-C disinfection robot. Int J Environ Res Public Health. 2023; 20:(5) https://doi.org/10.3390/ijerph20054284

Centers for Disease Control and Prevention. Guidelines for environmental infection control in health-care facilities 2003. 2003. https://tinyurl.com/4ufek3vf (accessed 22 August 2023)

Dippenaar R, Smith J. Impact of pulsed xenon ultraviolet disinfection on surface contamination in a hospital facility's expressed human milk feed preparation area. BMC Infect Dis. 2018; 18:(1) https://doi.org/10.1186/s12879-018-2997-9

Duke University. Medical Center Library & Archives. Evidence-based practice: PICO. 2023. https://guides.mclibrary.duke.edu/ebm/pico (accessed 22 August 2023)

Durango-Giraldo G, Cardona A, Zapata JF, Santa JF, Buitrago-Sierra R. Titanium dioxide modified with silver by two methods for bactericidal applications. Heliyon. 2019; 5:(5) https://doi.org/10.1016/j.heliyon.2019.e01608

European Centre for Disease Prevention and Control. Assessing the health burden of infections with antibiotic-resistant bacteria in the EU/EEA, 2016-2020. 2022. https://tinyurl.com/nu7mmzsf (accessed 22 August 2023)

Gostine A, Gostine D, Donohue C, Carlstrom L. Evaluating the effectiveness of ultraviolet-C lamps for reducing keyboard contamination in the intensive care unit: A longitudinal analysis. Am J Infect Control. 2016; 44:(10)1089-1094 https://doi.org/10.1016/j.ajic.2016.06.012

Green C, Pamplin JC, Chafin KN, Murray CK, Yun HC. Pulsed-xenon ultraviolet light disinfection in a burn unit: impact on environmental bioburden, multidrug-resistant organism acquisition and healthcare associated infections. Burns. 2017; 43:(2)388-396 https://doi.org/10.1016/j.burns.2016.08.027

Hu ZT, Chen Y, Fei YF An overview of nanomaterial-based novel disinfection technologies for harmful microorganisms: mechanism, synthesis, devices and application. Sci Total Environ. 2022; 837 https://doi.org/10.1016/j.scitotenv.2022.155720

Kitagawa H, Mori M, Hara T, Kashiyama S, Shigemoto N, Ohge H. Effectiveness of pulsed xenon ultraviolet disinfection for Clostridioides (Clostridium) difficile surface contamination in a Japanese hospital. Am J Infect Control. 2021; 49:(1)55-58 https://doi.org/10.1016/j.ajic.2020.05.032

Knottnerus A, Tugwell P. STROBE—A checklist to STrengthen the Reporting of OBservational studies in Epidemiology. J Clin Epidemiol. 2008; 61:(4) https://doi.org/10.1016/j.jclinepi.2007.11.006

Linam WM, Trivedi KK, Schaffzin JK. Don't just do it – conducting and publishing improvement science in infection prevention and antibiotic stewardship. Antimicrob Steward Healthc Epidemiol. 2022; 2:(1) https://doi.org/10.1017/ash.2021.259

Lucciola M, Vivian M. West Gordon. Breaking the chain of infection: ultraviolet light to disinfect hospital keyboards. Medsurg Nursing. 2022; 31:(3)145-164

Maclean M, McKenzie K, Anderson JG, Gettinby G, MacGregor SJ. 405 nm light technology for the inactivation of pathogens and its potential role for environmental disinfection and infection control. J Hosp Infect. 2014; 88:(1)1-11 https://doi.org/10.1016/j.jhin.2014.06.004

Medioli F, Bacca E, Faltoni M Is it possible to eradicate carbapenem-resistant Acinetobacter baumannii (CRAB) from endemic hospitals?. Antibiotics (Basel). 2022; 11:(8) https://doi.org/10.3390/antibiotics11081015

Morikane K, Suzuki S, Yoshioka J, Yakuwa J, Nakane M, Nemoto K. Clinical and microbiological effect of pulsed xenon ultraviolet disinfection to reduce multidrug-resistant organisms in the intensive care unit in a Japanese hospital: a before-after study. BMC Infect Dis. 2020; 20:(1) https://doi.org/10.1186/s12879-020-4805-6

Nagaraja A, Visintainer P, Haas JP, Menz J, Wormser GP, Montecalvo MA. Clostridium difficile infections before and during use of ultraviolet disinfection. Am J Infect Control. 2015; 43:(9)940-945 https://doi.org/10.1016/j.ajic.2015.05.003

Pereira AR, Braga DFO, Vassal M, Gomes IB, Simões M. Ultraviolet C irradiation: a promising approach for the disinfection of public spaces?. Sci Total Environ. 2023; 879 https://doi.org/10.1016/j.scitotenv.2023.163007

Quinn MM, Henneberger PK Cleaning and disinfecting environmental surfaces in health care: toward an integrated framework for infection and occupational illness prevention. Am J Infect Control. 2015; 43:(5)424-34 https://doi.org/10.1016/j.ajic.2015.01.029

Rangel K, Cabral FO, Lechuga GC, Villas-Bôas MHS, Midlej V, De-Simone SG. Effectiveness evaluation of a UV-C-Photoinactivator against selected ESKAPE-E pathogens. Int J Environ Res Public Health. 2022; 19:(24) https://doi.org/10.3390/ijerph192416559

Sampathkumar P, Folkert C, Barth JE A trial of pulsed xenon ultraviolet disinfection to reduce Clostridioides difficile infection. Am J Infect Control. 2019; 47:(4)406-408 https://doi.org/10.1016/j.ajic.2018.09.018

Sathitakorn O, Jantarathaneewat K, Weber DJ, Apisarnthanarak P, Rutjanawech S, Apisarnthanarak A. Efficacy of environmental cleaning protocol featuring real-time feedback with and without PX-UV in reducing the contamination of Gram-negative microorganisms on high-touch surfaces in four intensive care units in Thailand. Antibiotics (Basel). 2023; 12:(3) https://doi.org/10.3390/antibiotics12030438

Schaffzin JK, Wilhite AW, Li Z, Finney D, Ankrum AL, Moore R. Maximizing efficiency in a high occupancy setting to utilize ultraviolet disinfection for isolation rooms. Am J Infect Control. 2020; 48:(8)903-909 https://doi.org/10.1016/j.ajic.2020.05.004

Shahida S, Islam A, Dey B, Islam F, Venkatesh K, Goodman A. Hospital acquired infections in low and middle income countries: root cause analysis and the development of infection control practices in Bangladesh. Open Journal of Obstetrics and Gynecology. 2016; 6:(1)28-39 https://doi.org/10.4236/ojog.2016.61004

Shea BJ, Reeves BC, Wells G AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. BMJ. 2017; 358 https://doi.org/10.1136/bmj.j4008

Suetens C, Latour K, Kärki T Prevalence of healthcare-associated infections, estimated incidence and composite antimicrobial resistance index in acute care hospitals and long-term care facilities: results from two European point prevalence surveys, 2016 to 2017. Euro Surveill. 2018; 23:(46) https://doi.org/10.2807/1560-7917.ES.2018.23.46.1800516

Point prevalence survey of healthcare associated infections and antimicrobial use in European acute care hospitals, 2016-2017. 2023. https://tinyurl.com/2kmyuj5w (accessed 22 August 2023)

Torraco RJ. Writing integrative reviews of the literature: methods and purpose. International Journal of Adult Vocational Education and Technology. 2016; 7:(3)62-70 https://doi.org/10.4018/IJAVET.2016070106

Van den Brink R. The end of an antibiotic era. Bacteria's triumph over a universal remedy.New York (NY): Springer; 2021

van der Starre CM, Cremers-Pijpers SAJ, van Rossum C, Bowles EC, Tostmann A. The in situ efficacy of whole room disinfection devices: a literature review with practical recommendations for implementation. Antimicrob Resist Infect Control. 2022; 11:(1) https://doi.org/10.1186/s13756-022-01183-y

Vianna PG, Dale CR, Simmons S, Stibich M, Licitra CM. Impact of pulsed xenon ultraviolet light on hospital-acquired infection rates in a community hospital. Am J Infect Control. 2016; 44:(3)299-303 https://doi.org/10.1016/j.ajic.2015.10.009

Villacis JE, Lopez M, Passey D Efficacy of pulsed-xenon ultraviolet light for disinfection of high-touch surfaces in an Ecuadorian hospital. BMC Infect Dis. 2019; 19:(1) https://doi.org/10.1186/s12879-019-4200-3

Whittemore R, Knafl K. The integrative review: updated methodology. J Adv Nurs. 2005; 52:(5)546-553 https://doi.org/10.1111/j.1365-2648.2005.03621.x

Wang N, Shi C, Kang X. Design of a disinfection and epidemic prevention robot based on fuzzy QFD and the ARIZ algorithm. Sustainability. 2022; 14:(24) https://doi.org/10.3390/su142416341

Wong T, Woznow T, Petrie M Postdischarge decontamination of MRSA, VRE, and Clostridium difficile isolation rooms using 2 commercially available automated ultraviolet-C–emitting devices. Am J Infect Control. 2016; 44:(4)416-420 https://doi.org/10.1016/j.ajic.2015.10.016

Zeber JE, Pfeiffer C, Baddley JW Effect of pulsed xenon ultraviolet room disinfection devices on microbial counts for methicillin-resistant Staphylococcus aureus and aerobic bacterial colonies. Am J Infect Control. 2018; 46:(6)668-673 https://doi.org/10.1016/j.ajic.2018.02.001

Using photon disinfection technologies for reducing bioburden in hospitals

21 September 2023
Volume 32 · Issue 17

Abstract

Background:

Environmental cleaning and disinfection is the basis of the prevention of healthcare-acquired infections (HAIs).

Aim:

This study aimed to describe photon disinfection technologies (PDTs), report their impact on inactivating micro-organisms and preventing HAIs and to create recommendations for their implementation in hospital settings.

Methods:

An integrated literature review was completed to evaluate and report the impact of PDTs in hospital settings. The quality of 23 articles were assessed, their contents analysed and results reported according to the PICOT model.

Findings:

The microbiological impact of the PDT varied by micro-organism, settings and according to the used devices. It was crucial that environmental cleaning was completed before the disinfection.

Conclusion:

The implementation of PDT in the hospital setting requires inquiry from the viewpoints of microbiological, environmental, occupational, technical and human safety. To enhance the safe implementation of PDTs, the construction and use of evidence-based global standards for PDT are crucial.

Environmental cleaning and disinfection measures are the basis for clinical improvements in infection prevention and control (IPC), preventing harm to patients and others from healthcare-acquired infections (HAIs) and infections with multidrug-resistant organisms (MDROs) (Linam et al, 2022).

According to Suetens et al (2018) and the European Centre for Disease Prevention and Control (ECDC) (Suetens, 2023), in Europe the adjusted prevalence of patients with at least one HAI was estimated at 6.5%, that is 3.8 million patients with at least one HAI, and 4.5 million infection episodes in 2016–2017. In England, the HAI prevalence was 6.4%, in Northern Ireland 6.1%, in Scotland 4.3% and in Wales 5.7%. Of all the 19 624 HAIs reported by the ECDC, the most frequent were respiratory tract infections (pneumonia) at 21.4%, urinary tract infections (18.9%), surgical site infections (18.4%), bloodstream infections (10.8%) and gastrointestinal infections (8.9%). Clostridioides difficile infections accounted for 54.6% of the latter and 4.9% of all HAIs. The IPC measures that prevent microbial spreading during outbreaks will vary, dependent on the setting and structural characteristics of the particular clinical area (Medioli et al, 2022). The selection of effective environmental and other IPC measures against the spreading of microbial agents in hospital settings is difficult due to low quality or lack of controlled and microbial agent-specific intervention studies (Medioli et al, 2022). The implementation of environmental IPC measures involves balanced ecological, economic and non-harmful choices (Pereira et al, 2023). This study aimed to analyse photon disinfection technologies (PDTs) for IPC in healthcare settings. The study objectives were to:

  • Describe the photon disinfection methods implemented in hospitals
  • Report their impact on inactivating micro-organisms on hospital surfaces
  • Report their impact on preventing HAIs and
  • Create recommendations for implementing photon disinfection in hospital settings.

Background

Infected patients, healthcare workers and visitors, whether diagnosed or asymptomatic, all contaminate surfaces, medical devices and other people, compromising the microbiological safety of healthcare facilities and services. In 2011-2012, in European acute care hospitals, the most common micro-organisms in HAIs were Escherichia coli, Staphylococcus aureus, Enterococcus species spp, Pseudomonas aeruginosa, Klebsiella spp, Coagulase-negative staphylococci (CoNS), Candida spp and C. difficile (Suetens, 2023). In European hospitals, the fast-spreading MDROs require immediate actions by mutual and multidisciplinary collaboration (Van den Brink, 2021).

Globally, C. difficile infections are among the most common HAIs. In the UK, C. difficile ranked as the third most common anaerobic bacilli (Suetens et al, 2023). Worldwide, a mean prevalence of 14.9% is reported in hospital environments, with the highest being 51.1% in India, 17.8% in the UK and 3.9% in Canada. The lowest reported was 1.6% in the USA (Borji et al, 2022). Birru et al (2021) reported 71 (71%) of 99 inanimate objects and patient care equipment were contaminated in an Ethiopian hospital. Gram-positive bacteria, CoNS, (52.2%) and S. aureus (47.7%) were the most common microbes followed by Gram-negative Acinetobacter spp (28.5%) and Klebsiella spp (23.8%). S. aureus (100%) and CoNS (78%) showed resistance against penicillin. Of the Acinetobacter spp bacteria found, all were resistant to ceftriaxone and ampicillin. All the Klebsiella spp bacteria were resistant to ampicillin and trimethoprim–sulfamethoxazole and of the Citrobacter spp, Enterobacter spp, Salmonella spp, E. coli and Serratia spp 3, all were found to be 100% resistant to amoxicillin, ampicillin, and trimethoprim–sulfamethoxazole. In this Ethiopian hospital case, the overall prevalence of MDRO was 57.7% (Birru et al 2021).

In 2019, antimicrobial resistance (AMR) was estimated to cause 4.95 million deaths globally. Of those deaths, 1.27 million were caused by bacterial AMR (Antimicrobial Resistance Collaborators, 2022). In the EU/EEA, the annual number of cases of infections caused by bacterium–antibiotic resistance combinations ranged from 685 433 in 2016 to 865 767 in 2019, with an annual number of attributable deaths ranging from 30 730 in 2016 to 38 710 in 2019. The disability-adjusted life years (DALYs) of people harmed by infection by antibiotic-resistant microbes were estimated to range from 909 488 in 2016 to 1 101 288 in 2019. Of the infections caused by antibiotic-resistant bacteria, 70.9% were estimated to be HAIs (ECDC, 2022). According to Shahida et al (2016) the HAIs rates are higher in low-income countries with limited resources than in the high-income countries. For example, in some Bangladesh hospitals, the HAI rates have exceeded 30%.

Conventional cleaning and disinfection measures

The Centers for Disease Control and Prevention (CDC) (2003) in the USA has recommend implementing ‘the Spaulding levels of disinfection’ for devices and surfaces not requiring sterility for safe use. The highly toxic ‘high-level’ disinfectants (such as hydrogen peroxide) inactivate all vegetative bacteria, mycobacteria, viruses, fungi and some bacterial spores and are appropriate for heat-sensitive, semi-critical instruments. The ‘intermediate-level’ disinfectants (such as sodium hypochlorite) do not kill bacterial spores, but can inactivate, for example, the more chemical-resistant Mycobacterium tuberculosis var. bovis; even M. bovis is more resistant to chemical germicides than ordinary vegetative bacteria, fungi, and medium to small viruses with or without lipid envelopes. The ‘low-level’ disinfectants (such as iodophors) inactivate ordinary vegetative bacteria, fungi, and enveloped viruses, such as human immunodeficiency (HIV), influenza viruses and some enveloped viruses.

Surfaces that require cleaning, disinfection or sterilisation are classified according to their potential to transmit an infection at the time of use (Quinn et al, 2015). According to the CDC (2003) the following factors influence the choice of the disinfection procedure for environmental surfaces, the:

  • Nature of the item to be disinfected
  • Number of micro-organisms present
  • Innate resistance of the micro-organisms to the inactivating effects of the germicide
  • Amount of organic soil present
  • Type and concentration of germicide used
  • Duration and temperature of germicide contact
  • If using a proprietary product, other specific indications and directions for use.

In hospitals, it is important to consider the microbial activity, burden, and risks for the patients and personnel, as well as the number of people in the environment, amount of activity, amount of moisture, presence of material capable of supporting microbial growth, the rate at which organisms suspended in the air are removed, and the type of surface and orientation, that is, horizontal or vertical. In practice, the potential for direct patient contact, degree and frequency of hand contact, and potential contamination of the surface with bodily substances or environmental sources of micro-organisms (such as soil, dust and water) are important for selecting strategies for cleaning and disinfecting surfaces in patient-care areas.

The CDC recommendations (2003) highlighted that cleaning is the basis for more specific disinfection measures by removing soil and organic contamination caused by micro-organisms from surfaces and medical or care devices by scrubbing. The use of chemical surfactants or detergents and water aims to wet, emulsify or reduce surface tension, thereby improving the cleaning effect. It is important to define the residual effects, time active and safety of cleaning and disinfection products and assess the conditions under which a one-step process with combined detergent-disinfectant is as effective for reducing contamination on surfaces compared to a two-step process in which cleaning is followed by disinfection (Quinn et al, 2015).

Photon disinfection techniques

PDTs have the potential to reduce the bioburden on hospital surfaces in an environmentally and occupationally safer manner than conventional techniques (Rangel et al, 2022; Pereira et al, 2023) The drugs, chlorination, ozonation and ultraviolet disinfection used in the sterilisation of water, air, food and other fields have unwanted effects. For example, the by-products of ozonation and chlorination are potential risks for cancer, the energy consumption of ultraviolet (UV) disinfection is high, and some microbes become naturally resistant to it (Hu et al, 2022). Disinfectants have cytotoxic and neurotoxic, mutagenic, and even depressant effects on the central nervous system in the human body (Pereira et al, 2023).

Photon disinfection occurs as a series of photophysical and photochemical reactions leading to a photodynamic inactivation of biomolecules by oxidising the DNAs and RNAs of the microbial cells. PDTs with different ranges of light wavelengths are used to inactivate the pathogens on hospital surfaces (Cabral and Ag, 2019). The effectiveness of disinfection depends on the radiation dose causing cellular damage by irradiation, the distance separating the radiation source from the contaminated surface, the nature and concentration of micro-organisms and, especially, the temperature and humidity of the environment. Different micro-organisms have varying sensitivity to irradiation (Rangel et al, 2022).

The electromagnetic spectrum (100–400 nanometers (nm)) of UV rays occurs between the extreme of the visible region and the X-ray bands. The UV region can be divided according to their wavelength and energy: UVA region (315–400 nm), UVB region (280–315 nm), and UVC region (100–280 nm). UVC irradiation of high energy and short wavelengths is reported to possess intensive potential for germicidal disinfection (Bhardwaj et al, 2021). The common 254 nm UVC (used for example in ‘UVD robots’) is considered harmful to human health, unlike the short wavelength, very low dose-rate far-UVC at 222 nm, which is reported to be safe for occupied spaces and effective for disinfection (Pereira et al, 2023).

Methods

An integrated literature review was completed in five stages (Whittemore and Knafl, 2005; Torraco, 2016):

  • Problem identification
  • Literature search
  • Data evaluation
  • Data analysis
  • Presentation of the results, from which the authors created recommendations for the implementation of PDT in hospital settings.

The PICOT model (Patient, Intervention, Comparison, Outcome and Time) was used in problem identification, the formulation of the study questions, data search and description of the selected studies (Duke University, 2023). The type of research questions according to the PICOT model were

  • What PDTs are used in hospital environments? (I)
  • What impact do PDTs have on the microbial burden on hospital surfaces? (O, I, C)
  • What impact do PDTs have on the HAI rates of hospital patients? (P, O, I)
  • What was the time limit? Publications reviewed were time limited to 1 January 2010 to 28 April 2023 (T).

Data searches were completed in 2021 and 2022 on the CINAHL, PubMed, ProQuest and ScienceDirect databases and reported as one search as part of a master's thesis by the first author (Mohamed Nazeer, 2021). The most recent search in 2023 was completed from ProQuest and Science Direct only. In total, 24 articles were initially selected.

Inclusion and exclusion criteria

Inclusion criteria for the selected studies were peer-reviewed scientific full text English language publications (qualitative, quantitative, mixed methods research, systematic literature review, integrative literature reviews), completed in hospital settings investigating photon disinfection technology/methods, ultraviolet, blue light, blue-violet light, and catalytic coating. The exclusion criteria were thesis reports, newspaper articles, editorials, abstracts only, conference proceedings, books, case reports, narrative literature reviews and commercial advertisement. Studies in dentistry, oral care, elderly care, water processing, wound care, food disinfection, non-PDT-related disinfection technologies, and in language other than English were also excluded.

Appraisal of article quality

Both authors appraised the quality of the articles independently to minimise the risk of inaccurate results (Whittemore and Knafl, 2005; Torraco, 2016) using the STrengthening the Reporting of OBservational studies in Epidemiology (STROBE) method (Knottnerus and Tugwell, 2008) (n=20). The systematic literature reviews gained in 2023 (n=3) were reviewed by the AMSTAR tool, a critical appraisal tool for systematic reviews (Shea et al, 2017). Differences in appraisals were solved by discussion between the authors. The authors set a 70% threshold for accepted articles, based on the STROBE or AMSTAR scoring systems. Articles scoring below 70% were considered low quality, 71-85% were considered moderate and more than 86% were considered high-quality articles (Knottnerus and Tugwell, 2008). Of the 24 articles assessed, 23 gained the required 70% level in quality rating. The rejected article by Lucciola et al (2022) focused on the disinfection of keyboards only in hospital settings with low quality (62.5%). The 23 articles are listed in Table 1.


Table 1. Studies on photon disinfection technologies implemented in hospital settings reviewed in the study
Studies on photon disinfection technologies' impact on inactivating micro-organisms Studies on photon disinfection technologies' impact on hospital-acquired infections

Data extraction

The text of the articles (n=23) was analysed according to the verification described by Whittemore and Knafl (2005). The descriptive information and the results of the article studies were compared and summarised. Recommendations were drawn up by comparing the data with the CDC (2003) recommendations for conventional environmental cleaning and disinfection.

Results

Of the selected 23 studies, 10 were carried out in the USA, one in Canada, one in Ecuador, four in the UK, two in Italy, one in the Netherlands, two in Japan, one in Thailand, and one in South Africa. The PDT devices evaluated and micro-organisms detected were reported inconsistently.

Photon disinfection methods implemented in healthcare settings

The most often reported PDTs were portable pulsed xenon ultraviolet (PX-UV) devices (n=15) with UVC or UVD radiation. In some studies, the radiation type was not reported. The PX-UV, a non-touch device with a non-mercury xenon flash lamp, is reported as an efficient technology in disinfecting floors and high-touch surfaces, and it has proven efficacy in eliminating 95-99% of MDROs in healthcare settings (Dippenaar and Smith, 2018; Casini et al, 2019; Villacis et al, 2019). The other reported devices were a focused multivector ultraviolet (FMUV) system with shadowless delivery (n=1) (giving direct radiation towards the surface to be disinfected) and a high-intensity narrow-spectrum light environmental decontamination system (HINS-light EDS) (n=3). In the most recent studies, the UVC devices were reported as robots (n=2) and in the older studies as mercury lamps (n=2).

Impact of the PDT in inactivating the micro-organisms

In the reviewed studies, the staphylococcal-type organisms (n=9), C. difficile (n=9) and vancomycin-resistant enterococci (VRE) (n=5) were the most often screened micro-organism. In some studies, the micro-organisms were not clearly reported or were defined as colony-forming units (CFUs) (Zeber et al, 2018; Schaffzin et al, 2020). The micro-organisms were often reported according to their importance in the study setting. For example, in the study by Anderson et al (2018) ‘terminal rooms’, that is rooms from which a patient with a specific infection or colonisation with C. difficile, meticillin-resistant S. aureus (MRSA), VRE or MR Acinetob spp had been discharged were then disinfected. The impact of the PDTs in inactivating the micro-organisms varied. In some studies, 100% reduction was reported (Casini et al, 2019), whereas in other studies no statistically significant reduction was found. The reduction in microbial burden by low-pressure mercury UVC devices was reported high by Wong et al (2016), whereas Brite et al (2018) did not find a statistically significant reduction in C. difficile and VRE burden.

Bache et al (2018) reported a decrease of between 22% and 86% in the mean number of surface bacteria during the use of the HINS-light EDS. Increases of between 78% and 309% occurred after the light switched off. Maclean et al (2010) reported the recovery of bacterial counts after switching off the HINS-light EDS when the microbial burden increased up to 126% and 39.5 CFU. Bache et al (2012) reported a significant reduction in the average number of bacterial colonies following HINS-light EDS use of between 27% and 75%. The reported reduction gained by PX-UVD varied from 31% in patient rooms to 90% in a human milk preparation areas (for premature newborns).

The importance of pre-disinfection cleaning was reported for example by Armellino et al (2019) and Casini et al (2019). Villacis et al (2019) reported that the PX-UV was an efficacious technology when used after manual cleaning, gaining a significant reduction in MDRO. Wong et al (2016) reported UVC devices were effective in addition to manual cleaning but limited to disinfecting high concentrations of organisms in the presence of proteins. The FMUV disinfection was reported to reduce bioburden on hospital environmental surfaces rapidly due to its high UV intensity (Armellino et al, 2019). The dose-calculating Tru-D SmartUVC device was reported to disinfect vegetative MRSA and VRE and was sporicidal for C. difficile (Wong et al, 2016).

Impact of the PDT in preventing HAIs

The impact of the PDT devices in HAI (or the transmission of the micro-organisms) were reported in six studies (Table 1). In the trial by Anderson et al (2018) in nine US hospitals with a baseline incidence rate of HAI of 19.5 per 10000 patient days, no statistically significant decrease after standard (18.1%), UV (17.2%), bleach (17.5%) or UV and bleach (17.4%) disinfection techniques were measured according to the C. difficile, MRSA, VRE and multidrug resistance Acinetobacterium spp levels recorded, nor differences in HAIs between disinfection techniques reported. During the UV-radiation period the risk for the acquisition of C. difficile and VRE decreased.

Schaffzin et al (2020) reported no direct causation between PDTs and HAIs but reported the benefits of using 2 LightStrike UV-C robots in the reduction of micro-organisms.

Vianna et al (2016) reported a 29% facility-wide reduction in C. difficile, MRSA and VRE and a 45%, 56% and 87% reduction, respectively, in the rates in the intensive care unit (ICU), being statistically significant only in the VRE by PX-UV.

Nagaraja et al (2015) reported a 22% reduction in the hospital-acquired C. difficile rate during use of the pulsed xenon UVD period, but the length of hospital stay due to hospital-acquired C. difficile-infection remained unchanged in the ICU.

Sampathkumar et al (2019) reported C. difficile infection rates decreased significantly in the intervention units compared with control units during the 6 months of PX-UV disinfection. In the intervention units, VRE acquisition also reduced.

Discussion

This integrated literature review was a theoretical study requiring no ethical review but the careful consideration of potential bias, lack of rigour and inaccuracy in selecting, reviewing, analysing, and reporting the combination and complexity of empirical and theoretical reports incorporating diverse methodologies (Whittemore and Knafl, 2005).

The burden of HAIs for infection prevention and treatment

HAIs cause a great financial, economic and human burden requiring excessive preventive and treatment measures. According to Medioli et al's (2022) literature review, the most frequent IPC measures in controlling carbapenem-resistant Acinetobacter baumannii (CRAB) in ICU settings are environmental disinfection (100%) performed with 10% sodium hypochlorite; implementation of hand hygiene with alcohol-based hand rub (91%); contact precautions (83%); staff education (83%); additional active screening (83%); cohorting of staff and patients (75%); monitoring of environmental cleaning (66%); genotyping micro-organisms (66%); daily chlorhexidine baths (58%); antimicrobial stewardship/monitoring of the antibiotic consumption (58%); active rectal screening (50%); environmental cultures (41%); and closing or stopping admissions to the ward (33%).

PDTs as a means to reduce the microbial burden and HAIs

The study by Anderson et al (2018) was a clinical trial comparing the impact of UV radiation and bleach in different combinations in terminal rooms. In these studies the types of micro-organisms and study settings were controlled showing significant reduction in hospital-wide risk for multidrug-resistant C. difficile, MRSA and VRE organisms.

Bache et al (2012; 2018) showed the effectiveness of the HINS-light EDS against VRE and staphylococcal microbes but also its weaknesses in producing a stable antimicrobial effect in some hospital environments.

Beal et al (2016) reported the importance of the exposure time being long enough in reducing the microbial burden. Required time, a microbe-specific PDT and type of setting are all important factors to be taken into the consideration when selecting and using PDTs.

The review of selected studies, such as the study by Schaffzin et al (2020), revealed the difficulties in showing the impact of PDTs against HAIs. Anderson et al (2018) reported the impact of PDT against environmental micro-organisms but not HAIs. Other HAI impact studies (Nagaraja et al, 2015; Vianna et al, 2016; Sampathkumar et al, 2019; Schaffzin et al, 2020) reported reductions in HAI transmission rates, making the interpretation of their results challenging. For example, Morikane et al (2020) did not report the reduction of HAIs but the transmission of micro-organisms. Nagaraja et al (2015) reported reduction of C. difficile infections without showing differences in hospital stay between patients with hospital- and community-acquired C. difficile infections.

Manual cleaning remains essential in preparing for the PDT measures. Armellino et al (2019) reported the lack of thoroughness in the cleaning of contaminated surfaces being linked to an increased risk of infection to the next occupant of the hospital room. Implementation of manual cleaning prior to the use of PDT was reported important by the CDC (2003) and several other reviewed studies.

Facilitators and barriers to the use of PDTs

Usability of the PDTs were reported in a few studies. Bache et al (2012) reported the HINS-light EDS having the ability to be operated continuously in inpatient isolation rooms because it was efficient, simple to run, unobtrusive, and neither dependent on staff compliance nor requiring any additional staff time to implement. Brite et al (2018) reported use of an automated datalog, which recorded the room number, environmental services operator identification, date, time, number of pulses delivered during device operation time and amount of energy emitted, as well as any error codes. This was introduced to increase the compliance of housekeeping personnel with the use of PX-UV disinfection in the routine cleaning of terminal rooms.

Armellino et al (2019) identified challenges in the adoption of UV devices, for example, in selecting rooms that would benefit most from the PDT, and with the time required for the terminal room disinfection. In addition, shadowing, sharp drop-outs in UV intensity with distance, and difficulties in disinfecting all sides of patient care equipment were reported to hinder the successful use of UV technology in hospitals. All of these barriers are possible to overcome by the ‘shadowless delivery’ technology and performance of the focused multivector ultraviolet (FMUV) system.

Safety of PDT devices

The use of traditional chemical disinfection methods have been challenged due to their harmful impacts on human health and environmental safety. The HINS-light EDS emits blue-violet light; white LEDs reported safer than the old mercury lamps (Wong et al, 2016). Beal et al (2016) reported PX-UV devices not containing mercury bulbs, unlike some continuous UV decontamination devices, being occupationally and environmentally safe with no need for mercury disposal. The authors found no papers comparing the safety of traditional chemical disinfection and PDT disinfection measures. The novel PDT devices make it possible for the staff to stay in the room during the disinfection. For example, the FMUV devices enable personnel to conduct manual cleaning in parallel with the UV disinfection process (Armellino et al, 2019). In some devices the motion sensors shut off the device if any movement is detected inside the room being disinfected (Casini et al, 2019).

Current improvements in PDT devices

In addition to the measures developed for the disinfection of entire patient rooms, small-scale devices are also available for more limited use. Rangel et al (2022) reported using a commercial shoe sole disinfection device with a UVC exposure time of 20 seconds showing 100% reduction in CFUs in P. aeruginosa, S. enterica, E. faecalis, S. aureus, A. baumannii and E. coli.

Blanchard et al (2022) evaluated the daily use of a bench-top device for disinfecting high-touch items, such as ID patches in 20 seconds. Implementing UVC equipment that effectively decontaminates high bacterial load from daily items is an important addition to the other disinfection strategies already in place (Rangel et al, 2022). Wang et al (2022) reviewed a robot capable of completely replacing humans in the complete disinfection of rooms with the ability to climb stairs, distribute materials, conduct real-time monitoring, temperature measurement and other functions.

Durango-Giraldo et al (2019) improved the photocatalytic antibactericidal activity of UV disinfection against E. coli and S. aureus bacteria by UV disinfection with modified titanium oxide and additional silver in laboratory conditions. Environmentally safer non-metal nanomaterials are currently under investigation for disinfection and sterilisation. In hospitals, air purification, disinfection and sterilisation technologies are used (Hu et al, 2022) in addition to base-line environmental cleaning and disinfections. Intensive and expensive microbe-specific IPC measures are implemented in wards such as ICUs.

Limitations of the study

The authors of this article selected an integrated literature review as a method exploring the current status of the PDTs in infection prevention. The designs of the reviewed studies varied widely, which is typical for an integrated literature review (Whittemore and Knafl, 2005). Due to the variation in the tested PDTs and variations in microbes it was difficult to compare the studies. In addition, all these factors were reported inconsistently. That is why the authors set the 70% threshold for accepted articles (Knottnerus and Tugwell, 2008).

Conclusion

Standardised evaluation methods were not implemented in any of the reviewed studies, so the results of this integrated literature review are not necessarily generalisable even to similar hospital settings. Implementation of PDT in the hospital environment requires consistent inquiry from the viewpoints of the microbiological, environmental, occupational, technical, and human safety. To enhance the safe implementation of PDTs the construction and use of evidence-based global standards for PDT are crucial. For the safe and effective use of the PDT devices, more standardised research and education is important for all staff working in hospital environments, including housekeeping, patient care and technical personnel.

Effectiveness studies and cost analyses on tackling HAIs also require standardised protocols.

Recommendations

It is recommended to classify hospital surfaces requiring PDT disinfection according to their potential to transmit an infection at the time of use.

The following aspects are important to take into the consideration, including the:

  • Nature of the item to be disinfected
  • Burden of present micro-organisms
  • Activity of the present micro-organisms
  • Innate resistance of the micro-organisms to the inactivating techniques
  • Amount of organic soil present
  • Presence of material capable of supporting microbial growth, such as biofilm
  • Number of people in the environment
  • Type, duration and amount of the radiation
  • Risks of the PDT for the patients and personnel
  • Amount of the PDT activity
  • Type of surface and orientation (horizontal or vertical).

In practice, it is important to:

  • Equip patient rooms with only essential items and patient care equipment
  • Remove all unnecessary items and objects from the surfaces to be disinfected
  • Remove organic soil from the surfaces to be disinfected
  • Select the disinfection technology according to the potential or detected micro-organisms
  • Select the time, duration, and amount of the radiation according to the manufacturer's instruction
  • Consider the risk of PDT to the people present
  • Use personal protective equipment according to the manufacturer's instructions
  • Select the time and disinfection technology according to the type, the orientation of the surfaces and room occupancy.

KEY POINTS

  • In an era of microbial resistance, environmental cleaning and disinfection are the basis of the prevention of healthcare-acquired infections
  • It is important to classify surfaces that require cleaning, disinfection or sterilisation according to their potential to transmit an infection
  • To enhance the safe implementation of photon disinfection technologies (PDTs) the construction and use of evidence-based global standards for PDT are crucial
  • For the safe and effective use of PDT devices, education is important for all staff working in hospital environments, including housekeeping, patient care and technical personnel. Also, it is important to inform patients about the use of PTD and device-and-disinfection-related risks

CPD reflective questions

  • What are your responsibilities as a healthcare worker in the selection and use of photon disinfection technologies (PDTs) from the viewpoint of occupational safety?
  • What are the potential disadvantages to using PDT for environmental disinfection in hospital settings?
  • How would you enhance patient safety in environments where PDT is implemented?