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Nguyen TT, He C, Carter R, Ballard EL, Smith K, Groth R, Jaatinen E, Kidd TJ, Nguyen TK, Stockwell RE, Tay G, Johnson GR, Bell SC, Knibbs LD. The Effectiveness of Ultraviolet-C (UV-C) Irradiation on the Viability of Airborne Pseudomonas aeruginosa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph192013706. [PMID: 36294279 PMCID: PMC9602727 DOI: 10.3390/ijerph192013706] [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: 09/23/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 05/17/2023]
Abstract
Pseudomonas aeruginosa (Pa) is the predominant bacterial pathogen in people with cystic fibrosis (CF) and can be transmitted by airborne droplet nuclei. Little is known about the ability of ultraviolet band C (UV-C) irradiation to inactivate Pa at doses and conditions relevant to implementation in indoor clinical settings. We assessed the effectiveness of UV-C (265 nm) at up to seven doses on the decay of nebulized Pa aerosols (clonal Pa strain) under a range of experimental conditions. Experiments were done in a 400 L rotating sampling drum. A six-stage Andersen cascade impactor was used to collect aerosols inside the drum and the particle size distribution was characterized by an optical particle counter. UV-C effectiveness was characterized relative to control tests (no UV-C) of the natural decay of Pa. We performed 112 tests in total across all experimental conditions. The addition of UV-C significantly increased the inactivation of Pa compared with natural decay alone at all but one of the UV-C doses assessed. UV-C doses from 246-1968 µW s/cm2 had an estimated effectiveness of approximately 50-90% for airborne Pa. The effectiveness of doses ≥984 µW s/cm2 were not significantly different from each other (p-values: 0.365 to ~1), consistent with a flattening of effectiveness at higher doses. Modelling showed that delivering the highest dose associated with significant improvement in effectiveness (984 µW s/cm2) to the upper air of three clinical rooms would lead to lower room doses from 37-49% of the 8 h occupational limit. Our results suggest that UV-C can expedite the inactivation of nebulized airborne Pa under controlled conditions, at levels that can be delivered safely in occupied settings. These findings need corroboration, but UV-C may have potential applications in locations where people with CF congregate, coupled with other indoor and administrative infection control measures.
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Affiliation(s)
- Thi Tham Nguyen
- School of Public Health, The University of Queensland, Brisbane, QLD 4006, Australia
- Correspondence:
| | - Congrong He
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Robyn Carter
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
| | - Emma L. Ballard
- QIMR Berghofer Institute of Medical Research, Brisbane, QLD 4006, Australia
| | - Kim Smith
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
| | - Robert Groth
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Esa Jaatinen
- School of Chemistry and Physics, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Timothy J. Kidd
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4032, Australia
- Pathology Queensland, Royal Brisbane and Women’s Hospital, Brisbane, QLD 4006, Australia
| | - Thuy-Khanh Nguyen
- QIMR Berghofer Institute of Medical Research, Brisbane, QLD 4006, Australia
| | | | - George Tay
- The Prince Charles Hospital, Brisbane, QLD 4032, Australia
| | - Graham R. Johnson
- International Laboratory for Air Quality & Health, School of Earth and Atmospheric Sciences, Faculty of Science, Queensland University of Technology (QUT), Brisbane, QLD 4000, Australia
| | - Scott C. Bell
- Centre for Children’s Health Research, Brisbane, QLD 4101, Australia
- The Prince Charles Hospital, Brisbane, QLD 4032, Australia
- Faculty of Medicine, The University of Queensland, Brisbane, QLD 4006, Australia
- Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Luke D. Knibbs
- Public Health Unit, Sydney Local Health District, Camperdown, NSW 2050, Australia
- Faculty of Medicine and Health, School of Public Health, The University of Sydney, Sydney, NSW 2006, Australia
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Combination antimicrobial susceptibility testing of multidrug-resistant Stenotrophomonas maltophilia from cystic fibrosis patients. Antimicrob Agents Chemother 2012; 56:4071-7. [PMID: 22585220 DOI: 10.1128/aac.00072-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Stenotrophomonas maltophilia is increasingly being isolated from the respiratory tract of individuals with cystic fibrosis, and, because of its multidrug-resistant nature, the selection of suitable treatment regimens can be problematical. Etest methodology was used to facilitate MIC and antimicrobial combination testing on 80 isolates of S. maltophilia cultured from the respiratory tract of Scottish individuals with cystic fibrosis between 2001 and 2010. The overall rate of susceptibility for the 1,410 MIC tests was 23.1%, and resistance was 68.9%. The most active antimicrobials were minocycline, co-trimoxazole, and doxycycline, with 92.4%, 87.3%, and 58.8% of isolates being susceptible, respectively. Of the 517 combinations, 13.2% were synergistic, with the most synergistic being ticarcillin/clavulanate plus aztreonam (91.7% synergistic), ticarcillin/clavulanate plus colistin (40%), and ticarcillin/clavulanate plus levofloxacin (19.4%). Colistin plus tobramycin was the only antagonistic combination (0.2%). By the median susceptible breakpoint index, the most active combinations were minocycline plus co-trimoxazole (median index, 20), minocycline plus piperacillin-tazobactam (median, 20), and co-trimoxazole plus ceftazidime (median, 16.5). The increasing problem of multidrug resistance in organisms recovered from the respiratory tracts of individuals with cystic fibrosis is not going to go away. Current susceptibility testing methods do not address the slow-growing organisms associated with chronic infection, and interpretive standards are based on achievable blood levels of antimicrobials. Addressing these issues specifically for organisms recovered from the respiratory tracts of individuals with cystic fibrosis should lead to better therapeutic outcomes and improved wellbeing of individuals with cystic fibrosis.
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Sudfeld CR, Dasenbrook EC, Merz WG, Carroll KC, Boyle MP. Prevalence and risk factors for recovery of filamentous fungi in individuals with cystic fibrosis. J Cyst Fibros 2009; 9:110-6. [PMID: 20045384 DOI: 10.1016/j.jcf.2009.11.010] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2009] [Revised: 11/29/2009] [Accepted: 11/30/2009] [Indexed: 02/07/2023]
Abstract
BACKGROUND Filamentous fungi are frequently recovered from respiratory cultures of individuals with CF. METHODS A CF cohort database was utilized to determine filamentous fungal prevalence and risk factors. RESULTS The prevalence of filamentous fungal isolation increased from 2.0% in 1997 to 28.7% in 2007. The odds of isolating filamentous fungi during a quarter was greater in CF adults [p<0.001], during chronic oral antibiotic use [p=0.002] and increased with each 10% drop in FEV(1) percent predicted [p=0.005], while inhaled corticosteroids surprisingly decreased the likelihood [p=0.012]. The direction of these effects persisted after excluding individuals with ABPA. A sub-analysis determined older age [p=0.019] and use of inhaled antibiotics [p=0.011] were independent risk factors for onset of fungal colonization. CONCLUSIONS This study suggests that isolation of filamentous fungi in CF at JHH has increased and risk factors include older age, decreased lung function, and chronic oral antibiotics.
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Affiliation(s)
- Christopher R Sudfeld
- Department of Epidemiology, The Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe Street, 6th Floor, Baltimore, MD 21205, United States.
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