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Hamerlinck H, Aerssens A, Boelens J, Dehaene A, McMahon M, Messiaen AS, Vandendriessche S, Velghe A, Leroux-Roels I, Verhasselt B. Sanitary installations and wastewater plumbing as reservoir for the long-term circulation and transmission of carbapenemase producing Citrobacter freundii clones in a hospital setting. Antimicrob Resist Infect Control 2023; 12:58. [PMID: 37337245 DOI: 10.1186/s13756-023-01261-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/29/2023] [Indexed: 06/21/2023] Open
Abstract
BACKGROUND Accumulating evidence shows a role of the hospital wastewater system in the spread of multidrug-resistant organisms, such as carbapenemase producing Enterobacterales (CPE). Several sequential outbreaks of CPE on the geriatric ward of the Ghent University hospital have led to an outbreak investigation. Focusing on OXA-48 producing Citrobacter freundii, the most prevalent species, we aimed to track clonal relatedness using whole genome sequencing (WGS). By exploring transmission routes we wanted to improve understanding and (re)introduce targeted preventive measures. METHODS Environmental screening (toilet water, sink and shower drains) was performed between 2017 and 2021. A retrospective selection was made of 53 Citrobacter freundii screening isolates (30 patients and 23 environmental samples). DNA from frozen bacterial isolates was extracted and prepped for shotgun WGS. Core genome multilocus sequence typing was performed with an in-house developed scheme using 3,004 loci. RESULTS The CPE positivity rate of environmental screening samples was 19.0% (73/385). Highest percentages were found in the shower drain samples (38.2%) and the toilet water samples (25.0%). Sink drain samples showed least CPE positivity (3.3%). The WGS data revealed long-term co-existence of three patient sample derived C. freundii clusters. The biggest cluster (ST22) connects 12 patients and 8 environmental isolates taken between 2018 and 2021 spread across the ward. In an overlapping period, another cluster (ST170) links eight patients and four toilet water isolates connected to the same room. The third C. freundii cluster (ST421) connects two patients hospitalised in the same room but over a period of one and a half year. Additional sampling in 2022 revealed clonal isolates linked to the two largest clusters (ST22, ST170) in the wastewater collection pipes connecting the rooms. CONCLUSIONS Our findings suggest long-term circulation and transmission of carbapenemase producing C. freundii clones in hospital sanitary installations despite surveillance, daily cleaning and intermittent disinfection protocols. We propose a role for the wastewater drainage system in the spread within and between rooms and for the sanitary installations in the indirect transmission via bioaerosol plumes. To tackle this problem, a multidisciplinary approach is necessary including careful design and maintenance of the plumbing system.
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Affiliation(s)
- Hannelore Hamerlinck
- Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium.
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium.
| | - Annelies Aerssens
- Department of Infection Control, Ghent University Hospital, Ghent, Belgium
| | - Jerina Boelens
- Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
| | - Andrea Dehaene
- Department of Infection Control, Ghent University Hospital, Ghent, Belgium
| | - Michael McMahon
- Department of Infection Control, Ghent University Hospital, Ghent, Belgium
| | | | | | - Anja Velghe
- Department of Geriatrics, Ghent University Hospital, Ghent, Belgium
| | - Isabel Leroux-Roels
- Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
- Department of Infection Control, Ghent University Hospital, Ghent, Belgium
| | - Bruno Verhasselt
- Department of Laboratory Medicine, Ghent University Hospital, Ghent, Belgium
- Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
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Zhang T(T, Yao L, Gao Z, Wang F. Particle exposure risk to a lavatory user after flushing a squat toilet. Sci Rep 2022; 12:21088. [PMID: 36473899 PMCID: PMC9726816 DOI: 10.1038/s41598-022-25106-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
Squat toilets are widely used in developing countries due to local customs and low costs. The flushing of a squat toilet can entrain strong airflow and produce aerosols. This investigation constructed a lavatory mock-up with a squat toilet. The flushing-induced airflow was both visualized and quantitatively measured by particle image velocimetry. The maximum height of the impacted airflow was identified by an ultrasonic anemometer. For inference of the particle emission rate, the toilet bowl was covered by an enclosed box for particle concentration measurement. The risks from skin contact of the deposited particles on the flushing button and the door handle and the possible inhalation of the released aerosols were evaluated. The results revealed that flushing a squat toilet can drive toilet plume to rise up to 0.9 m above the toilet bowl. A single flushing process can produce 0.29 million particles with diameters greater than 0.3 μm, among which 90% of the particles are submicron-sized. The flushing may cause particles to deposit on the flushing button and lavatory door handle as well as inhalation exposure even remaining in the lavatory for half a minute after flushing, especially for those lavatory users whose respiratory zones are below 1.0 m.
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Affiliation(s)
- Tengfei (Tim) Zhang
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Lifang Yao
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Zilong Gao
- grid.30055.330000 0000 9247 7930School of Civil Engineering, Dalian University of Technology, Dalian, China
| | - Feng Wang
- grid.33763.320000 0004 1761 2484Tianjin Laboratory of Indoor Air Environmental Quality Control, School of Environmental Science and Engineering, Tianjin University, Tianjin, China
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Nunayon SS, Wang M, Zhang HH, Lai ACK. Evaluating the efficacy of a rotating upper-room UVC-LED irradiation device in inactivating aerosolized Escherichia coli under different disinfection ranges, air mixing, and irradiation conditions. JOURNAL OF HAZARDOUS MATERIALS 2022; 440:129791. [PMID: 36027747 DOI: 10.1016/j.jhazmat.2022.129791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/09/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
Cost-effective and safe air disinfection methods are urgently needed in various environmental public settings. A novel UVC-based disinfection system was designed and tested to provide a promising solution because of its effective inactivation of indoor bioaerosols at a low cost. UVC light-emitting diodes (UVC-LEDs) were utilized as the irradiation source. This system has the unique feature of rotating the UVC-LEDs to generate a "scanning irradiation" zone. Escherichia coli was aerosolized into an experimental chamber, exposed to UVC-LEDs, and sampled using an impactor. Effects of air mixing (well-mixed vs. poorly-mixed), transmission range (short vs. long), and irradiation mode (stationary vs. rotating) were evaluated. The system performs significantly well under the poorly-mixed condition. The results obtained from the short disinfection range indicate that the rotating UVC was approximately 70.5 % more effective than the stationary UVC for the poorly-mixed case. Further, we evaluated the performance of the long disinfection range under a poorly-mixed situation, and the disinfection efficacy was 84.6 % higher for the rotating irradiation than that of the stationary. About 0.59-1.34 J/m2 UV dose can be used to obtain one-log inactivation of E. coli. In conclusion, the novel rotating upper-room UVC-LED system is effective in reducing indoor pathogen transmission, and our findings are highly significant to a growing field where LEDs are applied for disinfection.
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Affiliation(s)
- Sunday S Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Minghao Wang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Hui H Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
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Mu J, Kang J. Indoor Environmental Quality of Residential Elderly Care Facilities in Northeast China. Front Public Health 2022; 10:860976. [PMID: 35602153 PMCID: PMC9116475 DOI: 10.3389/fpubh.2022.860976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
The indoor environmental quality is based on the indoor environmental performance of buildings, such as air temperature, lighting, and acoustics. These parameters have a specific impact on users' health and experience. This study explores the relationship between the indoor environment of residential elderly care facilities in cold regions and the sensitivity of the elderly to these facilities with the aim of improving the elderly care environment. This study measured the acoustic, lighting, and thermal environment in four residential elderly care facilities in Northeast China in spring, summer, autumn, and winter through a participant survey. In the residential elderly care facilities surveyed in this study, brightness and illuminance show a nonlinear relationship with lighting evaluation. With an increase in brightness and illuminance, the satisfaction of the lighting environment in different seasons first increases and then decreases. The relative humidity of the different types of rooms varies greatly in spring and less in winter. The average air quality score of the bedroom is higher than that of the activity room. The correlation between odor assessment and overall indoor environmental quality is very poor. The results of the questionnaire survey indicate that the participants were satisfied with the facilities' overall indoor environmental quality. This quality is affected by physical, environmental, and demographic factors. This study provides a reference for the design of other residential elderly care facilities.
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Affiliation(s)
- Jingyi Mu
- School of Architecture, Key Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and Technology, Ministry of Industry and Information Technology, Harbin Institute of Technology, Harbin, China
| | - Jian Kang
- Institute for Environmental Design and Engineering, The Bartlett, University College London, London, United Kingdom
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5
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Nunayon SS, Zhang HH, Chan V, Kong RYC, Lai ACK. Study of synergistic disinfection by UVC and positive/negative air ions for aerosolized Escherichia coli, Salmonella typhimurium, and Staphylococcus epidermidis in ventilation duct flow. INDOOR AIR 2022; 32:e12957. [PMID: 34796996 DOI: 10.1111/ina.12957] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 10/29/2021] [Accepted: 10/30/2021] [Indexed: 06/13/2023]
Abstract
The efficacy of the in-duct application of ultraviolet waveband C (UVC) emitting at 254 nm wavelength and air ions against aerosolized bacteria was studied in a full-scale 9-m long ventilation duct. Combined positive and negative ion polarities (bipolar ions) and combined UVC and ions were tested. The UVC was generated by a mercury-type UVC lamp and air ions were generated by positive and negative polarity ionizers. Escherichia coli (E. coli), Salmonella typhimurium (S. typhimurium), and Staphylococcus epidermidis (S. epidermidis)were tested at a concentration of 108 to 109 cells in 50 ml of sterilized distilled water. The case in which the positive ionizer was placed first, followed by the negative ionizer, demonstrated significantly higher disinfection efficiencies for E. coli (p = 0.007) and S. typhimurium (p < 0.001), but lower efficiency for S. epidermidis (p = 0.01) than the reversed sequence. The combination of UVC (3.71 J/m2 ) and air ions (1.13 × 1012 ions/m3 for positive ions and 8.00 × 1011 ions/m3 for negative ions) led to higher inactivation than individual disinfection agents operating under the same dose. A synergetic inactivation effect was observed for S. epidermidis under the combined UVC and positive ion case, while the combined UVC and negative ion case showed significant synergy effects for E. coli and S. typhimurium.
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Affiliation(s)
- Sunday S Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Hui H Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Vincent Chan
- Department of Biomedical Engineering, Khalifa University of Science and Technology, Abu Dhabi, UAE
| | - Richard Y C Kong
- Department of Chemistry, City University of Hong Kong, Hong Kong, China
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
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Kitagawa H, Kaiki Y, Tadera K, Nomura T, Omori K, Shigemoto N, Takahashi S, Ohge H. Pilot study on the decontamination efficacy of an installed 222-nm ultraviolet disinfection device (Care222™), with a motion sensor, in a shared bathroom. Photodiagnosis Photodyn Ther 2021; 34:102334. [PMID: 33971330 DOI: 10.1016/j.pdpdt.2021.102334] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/21/2021] [Accepted: 05/03/2021] [Indexed: 11/19/2022]
Abstract
BACKGROUND Toilet surfaces are contaminated with pathogens, and they may be a vector for disease transmission. In this study, we investigated the efficacy of an automated 222-nm ultraviolet C (UVC) disinfection device "Care222™," with a motion sensor, for removing bacterial contamination in a shared bathroom. METHODS Two automated UVC devices, deactivated by motion sensors, were mounted on the ceiling of two bathrooms; the emission window of the UVC device was covered in the non-treated bathroom. After irradiation, samples were collected from five surfaces at four time points/day for 5 days, and colony-forming units (CFUs) of aerobic bacteria (AB) were determined. The irradiation time was also measured. RESULTS UVC source deactivation time did not significantly differ between the bathrooms. There was a significant difference in the total AB CFUs between the treated and non-treated bathrooms. In the treated bathroom, the CFUs of AB of the toilet seat, control panel of the electric toilet seat, and top of the toilet paper holder were significantly lower than those of the control. The CFUs of AB at 9:00, 15:00, and 18:00 h in the treated bathroom were significantly lower than those of the control. CONCLUSIONS The automated 222-nm UVC disinfection device with a motion sensor significantly reduced AB surface contamination of a shared bathroom.
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Affiliation(s)
- Hiroki Kitagawa
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan; Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan; Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
| | - Yuki Kaiki
- Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kayoko Tadera
- Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan; Section of Clinical Laboratory, Division of Clinical Support, Hiroshima University Hospital, Hiroshima, Japan; Division of Laboratory Medicine, Hiroshima University Hospital, Hiroshima, Japan
| | - Toshihito Nomura
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan
| | - Keitaro Omori
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan
| | - Norifumi Shigemoto
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan; Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan; Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan; Translational Research Center, Hiroshima University, Hiroshima, Japan
| | - Shinya Takahashi
- Department of Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hiroki Ohge
- Department of Infectious Diseases, Hiroshima University Hospital, Hiroshima, Japan; Project Research Center for Nosocomial Infectious Diseases, Hiroshima University, Hiroshima, Japan
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7
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Mukherjee S, Boral S, Siddiqi H, Mishra A, Meikap BC. Present cum future of SARS-CoV-2 virus and its associated control of virus-laden air pollutants leading to potential environmental threat - A global review. JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2021; 9:104973. [PMID: 33462561 PMCID: PMC7805399 DOI: 10.1016/j.jece.2020.104973] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/06/2020] [Accepted: 12/20/2020] [Indexed: 05/05/2023]
Abstract
The world is presently infected by the biological fever of COVID-19 caused by SARS-CoV-2 virus. The present study is mainly related to the airborne transmission of novel coronavirus through airway. Similarly, our mother planet is suffering from drastic effects of air pollution. There are sufficient probabilities or evidences proven for contagious virus transmission through polluted airborne-pathway in formed aerosol molecules. The pathways and sources of spread are detailed along with the best possible green control technologies or ideas to hinder further transmission. The combined effects of such root causes and unwanted outcomes are similar in nature leading to acute cardiac arrest of our planet. To maintain environmental sustainability, the prior future of such emerging unknown biological hazardous air emissions is to be thoroughly researched. So it is high time to deal with the future of hazardous air pollution and work on its preventive measures. The lifetime of such an airborne virus continues for several hours, thus imposing severe threat even during post-lockdown phase. The world waits eagerly for the development of successful vaccination or medication but the possible outcome is quite uncertain in terms of equivalent economy distribution and biomedical availability. Thus, risk assessments are to be carried out even during the post-vaccination period with proper environmental surveillance and monitoring. The skilled techniques of disinfection, sanitization, and other viable wayouts are to be modified with time, place, and prevailing climatic conditions, handling the pandemic efficiently. A healthy atmosphere makes the earth a better place to dwell, ensuring its future lifecycle.
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Key Words
- 2019-nCoV, 2019 novel coronavirus
- ACE2, angiotensin-converting enzyme 2
- ALRI, Acute Lower Respiratory Infections
- ANN, artificial neural network
- API, air pollution index
- ASTM, American Society for Testing and Materials
- Aerosol or particulate matter
- Airborne virus
- BCG, Bacillus Calmette Guérin
- COCOREC, Collaborative Study COVID Recurrence
- COPD, Chronic Obstructive Pulmonary Disorder
- COVID-19, coronavirus disease, 2019
- CSG, Coronavirus Study Group
- CoV, Coronavirus
- Dispersion
- EPA, Environmental Protection Agency
- FCVS, filtered containment venting systems
- HEME, High-Efficiency Mist Eliminator
- ICTV, International Committee on Taxonomy of Viruses
- IHD, Ischemic Heart Disease
- ISO, International organization of Standardization
- IoT, Internet of Things
- MERS-CoV, Middle-East Respiratory Syndrome coronavirus
- NAAQS, National Ambient Air Quality Standard
- NFKB, nuclear factor kappa-light-chain-enhancer of activated B cells
- NRF2, nuclear factor erythroid 2-related factor 2
- Novel coronavirus
- PM, particulate matter
- Pathways of transmission
- Prevention and control measures
- ROS, reactive oxygen species
- SARS-CoV-2
- SARS-CoV-2, severe acute respiratory syndrome coronavirus 2
- USEPA, United States Environmental Protection Agency
- UVGI, Ultraviolet Germicidal Irradiation
- VOC, volatile organic compound
- WHO, World Health Organization
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Affiliation(s)
- Subhrajit Mukherjee
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Soumendu Boral
- School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Hammad Siddiqi
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Asmita Mishra
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
| | - Bhim Charan Meikap
- Department of Chemical Engineering, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, India
- Department of Chemical Engineering, School of Engineering, Howard College Campus, University of Kwazulu-Natal (UKZN), King George V Avenue, Durban 4041, South Africa
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Salgado BAB, Fabbri S, Dickenson A, Hasan MI, Walsh JL. Surface barrier discharges for Escherichia coli biofilm inactivation: Modes of action and the importance of UV radiation. PLoS One 2021; 16:e0247589. [PMID: 33730103 PMCID: PMC7968650 DOI: 10.1371/journal.pone.0247589] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 02/10/2021] [Indexed: 11/18/2022] Open
Abstract
Cold plasma generated in air at atmospheric pressure is an extremely effective antimicrobial agent, with proven efficacy against clinically relevant bacterial biofilms. The specific mode of bacterial inactivation is highly dependent upon the configuration of the plasma source used. In this study, the mode of microbial inactivation of a surface barrier discharge was investigated against Escherichia coli biofilms grown on polypropylene coupons. Different modes of exposure were considered and it was demonstrated that the long-lived reactive species created by the plasma are not solely responsible for the observed microbial inactivation. It was observed that a synergistic interaction occurs between the plasma generated long-lived reactive species and ultraviolet (UV) photons, acting to increase the antimicrobial efficacy of the approach by an order of magnitude. It is suggested that plasma generated UV is an important component for microbial inactivation when using a surface barrier discharge; however, it is not through the conventional pathway of direct DNA damage, rather through the synergistic interaction between liquid in the biofilm matrix and long-lived chemical species created by the discharge.
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Affiliation(s)
- Breno A. B. Salgado
- Centre for Plasma Microbiology, Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Stefania Fabbri
- Centre for Plasma Microbiology, Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Aaron Dickenson
- Centre for Plasma Microbiology, Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - Mohammad I. Hasan
- Centre for Plasma Microbiology, Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
| | - James L. Walsh
- Centre for Plasma Microbiology, Department of Electrical Engineering and Electronics, University of Liverpool, Liverpool, United Kingdom
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Lai ACK, Nunayon SS. A new UVC-LED system for disinfection of pathogens generated by toilet flushing. INDOOR AIR 2021; 31:324-334. [PMID: 32989792 PMCID: PMC7537215 DOI: 10.1111/ina.12752] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/27/2020] [Accepted: 09/15/2020] [Indexed: 06/11/2023]
Abstract
A new disinfection system utilizing UVC-LED irradiation was developed. The system was affixed to the toilet seat, and it was challenged by three bacteria strains. Different configurations were tested: 3-LEDs, 5-LEDs (two variants), and 8-LEDs. To determine the arrangement designs of LEDs with the optimum efficacy, two variants of 5-LEDs configurations were additionally considered-uniform and concentrated (2-sided) distributions. It was noticed that disinfection efficacy initially increased with the number of LEDs, but with 8-LEDs, the trend became almost non-obvious for surface disinfection and just marginally increased for airborne disinfection. The mean efficiencies for the surface disinfection ranged from 55.17 ± 23.89% to 72.80 ± 4.13% for E. coli; 36.65 ± 2.99% to 50.05 ± 13.38% for S. typhimurium; and 8.81 ± 3.23% to 39.43 ± 9.33% for S. epidermidis. Likewise, the mean efficiencies for airborne disinfection ranged from 42.17 ± 8.18% to 70.70 ± 4.80%; 40.40 ± 17.90% to 58.31 ± 13.87%; and 24.16 ± 3.81% to 42.79 ± 10.20% for E. coli; S. typhimurium; and S. epidermidis, respectively. Furthermore, the efficacy of the uniform irradiation was nearly twice that of the concentrated irradiation for surface disinfection and 17.70% higher for airborne disinfection, when tested against E coli. Collectively, these very promising results showcased that this compact, sustainable, and localized disinfection system has a high potential for the next generation of disinfection devices.
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Affiliation(s)
- Alvin C. K. Lai
- Department of Architecture and Civil EngineeringCity University of Hong KongKowloon TongHong Kong
| | - Sunday S. Nunayon
- Department of Architecture and Civil EngineeringCity University of Hong KongKowloon TongHong Kong
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McGinn C, Scott R, Donnelly N, Roberts KL, Bogue M, Kiernan C, Beckett M. Exploring the Applicability of Robot-Assisted UV Disinfection in Radiology. Front Robot AI 2021; 7:590306. [PMID: 33501347 PMCID: PMC7815819 DOI: 10.3389/frobt.2020.590306] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/12/2020] [Indexed: 01/21/2023] Open
Abstract
The importance of infection control procedures in hospital radiology departments has become increasingly apparent in recent months as the impact of COVID-19 has spread across the world. Existing disinfectant procedures that rely on the manual application of chemical-based disinfectants are time consuming, resource intensive and prone to high degrees of human error. Alternative non-touch disinfection methods, such as Ultraviolet Germicidal Irradiation (UVGI), have the potential to overcome many of the limitations of existing approaches while significantly improving workflow and equipment utilization. The aim of this research was to investigate the germicidal effectiveness and the practical feasibility of using a robotic UVGI device for disinfecting surfaces in a radiology setting. We present the design of a robotic UVGI platform that can be deployed alongside human workers and can operate autonomously within cramped rooms, thereby addressing two important requirements necessary for integrating the technology within radiology settings. In one hospital, we conducted experiments in a CT and X-ray room. In a second hospital, we investigated the germicidal performance of the robot when deployed to disinfect a CT room in <15 minutes, a period which is estimated to be 2-4 times faster than current practice for disinfecting rooms after infectious (or potentially infectious) patients. Findings from both test sites show that UVGI successfully inactivated all of measurable microbial load on 22 out of 24 surfaces. On the remaining two surfaces, UVGI reduced the microbial load by 84 and 95%, respectively. The study also exposes some of the challenges of manually disinfecting radiology suites, revealing high concentrations of microbial load in hard-to-reach places. Our findings provide compelling evidence that UVGI can effectively inactivate microbes on commonly touched surfaces in radiology suites, even if they were only exposed to relatively short bursts of irradiation. Despite the short irradiation period, we demonstrated the ability to inactivate microbes with more complex cell structures and requiring higher UV inactivation energies than SARS-CoV-2, thus indicating high likelihood of effectiveness against coronavirus.
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Affiliation(s)
- Conor McGinn
- School of Engineering, Trinity College Dublin, Dublin, Ireland
- Akara Robotics, Dublin, Ireland
| | - Robert Scott
- School of Engineering, Trinity College Dublin, Dublin, Ireland
| | | | - Kim L. Roberts
- Department of Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Marina Bogue
- Department of Microbiology, Trinity College Dublin, Dublin, Ireland
| | | | - Michael Beckett
- Department of Microbiology, Trinity College Dublin, Dublin, Ireland
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Barcelo D. An environmental and health perspective for COVID-19 outbreak: Meteorology and air quality influence, sewage epidemiology indicator, hospitals disinfection, drug therapies and recommendations. JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2020; 8:104006. [PMID: 32373461 PMCID: PMC7198433 DOI: 10.1016/j.jece.2020.104006] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 05/17/2023]
Abstract
This Opinion Paper wishes to provide a summary of recent findings and solutions for a better understanding of the environmental and health problems associated with COVID-19. The list of topics covered is large: meteorology and air quality factors with correlation number of infections, sewage waters as a way to reveal the scale of COVID-19 outbreak, current hospital disinfection procedures and new eco-friendly technologies and list of drug therapies recommend waiting for the desired vaccine to come. During the last two months we did notice an increase in the scientific literature regarding COVID-19 with a partial vision of this problem. The current Opinion Paper is one of the first attempts, to my understanding, to summarize and integrate environmental and human health aspects related to the monitoring, fate and treatment solutions for COVID-19. That being said I believe that this Opinion Paper can serve as multipurpose document, not only for scientists of different disciplines but for social media and citizens in general.
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Affiliation(s)
- Damia Barcelo
- Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain
- Catalan Institute for Water Research (ICRA), C/Emili Grahit 101, 17003 Girona, Spain
- College of Environmental and Resources Sciences, Zhejiang A&F University, Hangzhou 311300, China
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Barcelo D. An environmental and health perspective for COVID-19 outbreak: Meteorology and air quality influence, sewage epidemiology indicator, hospitals disinfection, drug therapies and recommendations. JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING 2020; 8:104006. [PMID: 32373461 DOI: 10.1016/j/jece.2020.104006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 05/28/2023]
Abstract
This Opinion Paper wishes to provide a summary of recent findings and solutions for a better understanding of the environmental and health problems associated with COVID-19. The list of topics covered is large: meteorology and air quality factors with correlation number of infections, sewage waters as a way to reveal the scale of COVID-19 outbreak, current hospital disinfection procedures and new eco-friendly technologies and list of drug therapies recommend waiting for the desired vaccine to come. During the last two months we did notice an increase in the scientific literature regarding COVID-19 with a partial vision of this problem. The current Opinion Paper is one of the first attempts, to my understanding, to summarize and integrate environmental and human health aspects related to the monitoring, fate and treatment solutions for COVID-19. That being said I believe that this Opinion Paper can serve as multipurpose document, not only for scientists of different disciplines but for social media and citizens in general.
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Affiliation(s)
- Damia Barcelo
- Water and Soil Quality Research Group, Department of Environmental Chemistry, IDAEA-CSIC, C/Jordi Girona 18-26, 08034 Barcelona, Spain
- Catalan Institute for Water Research (ICRA), C/Emili Grahit 101, 17003 Girona, Spain
- College of Environmental and Resources Sciences, Zhejiang A&F University, Hangzhou 311300, China
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Nunayon SS, Zhang H, Lai ACK. Comparison of disinfection performance of UVC-LED and conventional upper-room UVGI systems. INDOOR AIR 2020; 30:180-191. [PMID: 31688980 DOI: 10.1111/ina.12619] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/02/2019] [Accepted: 11/04/2019] [Indexed: 05/05/2023]
Abstract
We developed a novel, compact upper-room ultraviolet germicidal irradiation system with light-emitting diode sources (UR-UVGI-LED) to enhance the disinfection of bioaerosols in an enclosed room space. Its effectiveness was evaluated and compared with the conventional upper-room ultraviolet germicidal irradiation system with mercury vapor sources (UR-UVGI-MV). Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis were atomized under the well-mixed condition and exposed to UR-UVGI-LED (or UR-UVGI-MV) device. The intensity output of the UR-UVGI-LED was also varied from 0% (no LED), 25%, 50% to 100% to further evaluate the UR-UVGI-LED disinfection effectiveness under different power levels. The decay rates for UR-UVGI-LED ranged from -0.1420 ± 0.04 min-1 to -0.3331 ± 0.07 min-1 for Escherichia coli, -0.1288 ± 0.01 min-1 to -0.3583 ± 0.02 min-1 for Serratia marcescens, and -0.0330 ± 0.01 min-1 to -0.0487 ± 0.01 min-1 for Staphylococcus epidermidis. It was noticed that the intensity level had a non-linear influence on the UR-UVGI-LED's performance. The decay rates achieved by the UR-UVGI-MV system were -0.3867 ± 0.08 min-1 , -0.4745 ± 0.002 min-1 , and -0.1624 ± 0.02 min-1 for Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis, respectively. Hence, the disinfection performance of both UR-UVGI-LED and UR-UVGI-MV systems was comparable for Escherichia coli and Serratia marcescens. These results demonstrate that the UR-UVGI-LED system has a high potential to be used as a safe and effective irradiated light source to disinfect indoor airborne pathogens.
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Affiliation(s)
- Sunday S Nunayon
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Huihui Zhang
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong, China
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Linden KG, Hull N, Speight V. Thinking Outside the Treatment Plant: UV for Water Distribution System Disinfection. Acc Chem Res 2019; 52:1226-1233. [PMID: 31038919 DOI: 10.1021/acs.accounts.9b00060] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This work critically evaluates the current paradigm of water distribution system management and juxtaposes that with the potential benefits of employing UV irradiation, which we hope will catalyze a judicial re-evaluation of the current practices in water distribution system management and spur critical research and a new way of thinking about secondary disinfection across the extent of distribution systems. Given the recent advances in UV technology and the efficacy of UV disinfection against all pathogen classes, we now see UV applications for disinfection in many aspects of consumers lives: in water coolers, dishwashers, coffee makers, and disinfection of personal items like gym bags, water bottles, and toothbrushes. Public and regulatory concern over water quality and pathogens, especially the recent interest in building plumbing, calls out for new approaches to disinfection and distribution system management. We envision a new model for secondary disinfection in water distribution systems utilizing emerging germicidal UV LED-based disinfection. UV irradiation in water treatment can achieve high levels of disinfection of all pathogens and minimize or eliminate the formation of regulated disinfection byproducts. So why is UV not considered as a secondary disinfectant for distribution systems? In this Account, we lay out the logic as to the benefits and practicality of adding distributed UV treatment to assist in protection of distribution systems and protect water quality for human exposure. The possible locations of UV irradiation in distribution systems are envisioned, potentially including UV booster stations along the distribution network, UV in storage tanks or their inlet/outlets, LEDs distributed along pipe walls, small point of use/entry treatment systems for buildings/homes/taps, or submersible swimming or rolling UV LED drones to reach problem pipes and provide a "shock" treatment or provide sterilization after main breaks or repairs. The benefits of UV applications in water also include high effectiveness against chlorine-resistant protozoa, no added disinfection byproducts, and compatibility of adding of UV to existing secondary disinfection strategies for enhanced protection. Potential challenges and research needs are described, such as use of UV-compatible pipe materials, implementation of sensors to monitor distributed LEDs, management of waste heat from the rear surface of the LED, and understanding the potential for regrowth of opportunistic microorganisms. Another notable challenge is the relatively stagnant regulatory environment in some countries to develop frameworks for evaluation and acceptance of UV technology in distribution systems that require a chemical secondary disinfectant. Rapid advances in UV LED research has propelled the growth of this field, but needs still remain, including understanding behavior of biofilms in pipes under UV irradiation, including any beneficial effects that may be lost, the potential for fouling of LED emission surfaces and monitoring points, and provision of a distributed power network to run the LEDs. Regulators may want specific monitoring approaches and advances in real-time monitoring of microbial viability, and engineers may need to develop new approaches to overall management.
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Affiliation(s)
- Karl G. Linden
- University of Colorado Boulder, Civil, Environmental and Architectural Engineering, Boulder, Colorado 80309, United States
| | - Natalie Hull
- The Ohio State University, Department of Civil, Environmental, and Geodedic Engineering, Columbus, Ohio 43210, United States
| | - Vanessa Speight
- University of Sheffield, Department of Civil and Structural Engineering, University of Sheffield, Sheffield, S1 3JD U.K
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