1
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Hardison RL, Lee SD, Limmer R, Marx J, Taylor BM, Barriga D, Nelson SW, Feliciano-Ruiz N, Stewart MJ, Calfee MW, James RR, Ryan SP, Howard MW. Sampling and recovery of infectious SARS-CoV-2 from high-touch surfaces by sponge stick and macrofoam swab. J Occup Environ Hyg 2023; 20:506-519. [PMID: 37382490 DOI: 10.1080/15459624.2023.2231516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/30/2023]
Abstract
Effective sampling for severe acute respiratory syndrome 2 (SARS-CoV-2) is a common approach for monitoring disinfection efficacy and effective environmental surveillance. This study evaluated sampling efficiency and limits of detection (LODs) of macrofoam swab and sponge stick sampling methods for recovering infectious SARS-CoV-2 and viral RNA (vRNA) from surfaces. Macrofoam swab and sponge stick methods were evaluated for collection of SARS-CoV-2 suspended in a soil load from 6-in2 coupons composed of four materials: stainless steel (SS), acrylonitrile butadiene styrene (ABS) plastic, bus seat fabric, and Formica. Recovery of infectious SARS-CoV-2 was more efficient than vRNA recovery on all materials except Formica (macrofoam swab sampling) and ABS (sponge stick sampling). Macrofoam swab sampling recovered significantly more vRNA from Formica than ABS and SS, and sponge stick sampling recovered significantly more vRNA from ABS than Formica and SS, suggesting that material and sampling method choice can affect surveillance results. Time since initial contamination significantly affected infectious virus recovery from all materials, with vRNA recovery showing limited to no difference, suggesting that SARS-CoV-2 vRNA can remain detectable after viral infectivity has dissipated. This study showed that a complex relationship exists between sampling method, material, time from contamination to sampling, and recovery of SARS-CoV-2. In conclusion, data show that careful consideration be used when selecting surface types for sampling and interpreting SARS-CoV-2 vRNA recovery with respect to presence of infectious virus.
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Affiliation(s)
| | - Sang Don Lee
- U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | | | - Joel Marx
- Battelle Memorial Institute, Columbus, Ohio
| | | | | | | | | | - Michael J Stewart
- U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | - M Worth Calfee
- U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
| | | | - Shawn P Ryan
- U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
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2
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Rogers CA, Gaskin SE, Thredgold LD, Pukala TL. An approach to quantify ortho-phthalaldehyde contamination on work surfaces. Ann Work Expo Health 2023; 67:886-894. [PMID: 37436000 PMCID: PMC10410490 DOI: 10.1093/annweh/wxad039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 05/23/2023] [Accepted: 06/26/2023] [Indexed: 07/13/2023] Open
Abstract
Ortho-phthalaldehyde (OPA) is used as a high-level disinfectant for reusable medical devices in healthcare settings. The ACGIH recently adopted a Threshold Limit Value-Surface Limit (TLV-SL; 25 µg/100 cm2) for OPA surface contamination to prevent induction of dermal and respiratory sensitization following dermal exposure. However, there is no current validated method to measure OPA surface contamination. This study aimed to develop a standardized approach for sample collection and quantitative determination of OPA from work surfaces for use in risk assessment practices. The reported method utilises readily available commercial wipes to collect surface samples coupled with direct detection of OPA via liquid chromatography time of flight mass spectrometry (LC-ToF-MS). This approach avoided complex derivatization steps commonly required for the analysis of aldehydes. Method evaluation was conducted in accordance with the Occupational Safety and Health Administration (OSHA) surface sampling guidelines. Overall recoveries of 25 µg/100 cm2 of OPA from stainless steel and glass surfaces were 70% and 72%, respectively. The reported LOD for this method was 1.1 µg/sample and the LOQ was 3.7 µg/sample. OPA remained stable on the sampling medium for up to 10 days, when stored at 4 °C. The method was demonstrated in a workplace surface assessment at a local hospital sterilising unit, successfully detecting OPA on work surfaces. This method is intended to supplement airborne exposure assessment and provide a quantitative assessment tool for potential dermal exposure. When used in conjunction with a thorough occupational hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent sensitization risks in the workplace can be minimized.
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Affiliation(s)
- Caitlyn A Rogers
- Adelaide Exposure Science and Health, School of Public Health, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Sharyn E Gaskin
- Adelaide Exposure Science and Health, School of Public Health, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Leigh D Thredgold
- Adelaide Exposure Science and Health, School of Public Health, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Tara L Pukala
- Department of Chemistry, School of Physical Sciences, University of Adelaide, Adelaide, South Australia, 5005, Australia
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3
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Hui DS, Yung L, Chan KK, Ng SS, Lui G, Ko FW, Chan TO, Yiu K, Li Y, Chan MT, Yen HL. Risk of air and surface contamination during application of different non-invasive respiratory support for patients with COVID-19. Int J Infect Dis 2023; 133:60-66. [PMID: 37182546 PMCID: PMC10175076 DOI: 10.1016/j.ijid.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/02/2023] [Accepted: 05/06/2023] [Indexed: 05/16/2023] Open
Abstract
OBJECTIVES We compared the risk of environmental contamination among COVID-19 patients who received high flow nasal cannula (HFNC), non-invasive ventilation (NIV), and conventional oxygen therapy (COT) via nasal cannula for respiratory failure. METHOD Air was sampled from the hospital isolation rooms with 12 air changes/hr where 26 COVID-19 patients received HFNC (up to 60L/min, n=6), NIV (n=6), or COT (up to 5L/min of oxygen, n=14). Surface samples were collected from 16 patients during air sampling. RESULTS Viral RNA was detected at comparable frequency in air samples collected from patients receiving HFNC (3/54, 5.6%), NIV (1/54, 1.9%), and COT (4/117, 3.4%) (p=0.579). Similarly, the risk of surface contamination was comparable among patients receiving HFNC (3/46, 6.5%), NIV (14/72, 19.4%), and COT (8/59, 13.6%) (p=0.143). An increment in the cyclic thresholds of the upper respiratory specimen prior to air sampling were associated with a reduced SARS-CoV-2 detection risk in air [OR 0.83 (95%CI 0.69 - 0.96), p=0.027] by univariate logistic regression. CONCLUSION No increased risk of environmental contamination in the isolation rooms was observed in the use of HFNC and NIV versus COT among COVID-19 patients with respiratory failure. Higher viral load in the respiratory samples was associated with positive air samples.
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Affiliation(s)
- David S Hui
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong; SH Ho Research Center in Infectious Diseases, The Chinese University of Hong Kong.
| | - Louise Yung
- School of Public Health, University of Hong Kong
| | - Ken Kp Chan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Susanna S Ng
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Grace Lui
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Fanny W Ko
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Tat-On Chan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Karen Yiu
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong
| | - Yuguo Li
- Department of Mechanical Engineering, University of Hong Kong
| | - Matthew Tv Chan
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong; Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong
| | - Hui-Ling Yen
- School of Public Health, University of Hong Kong
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4
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Gómez-Castillo MA, Rivera Romero C, Reátegui-Ochoa K, Mamani Zapana E, Silva-Jaimes M. Ozone Efficacy for the Disinfection of Ambulances Used to Transport Patients during the COVID-19 Pandemic in Peru. Int J Environ Res Public Health 2023; 20:ijerph20105776. [PMID: 37239505 DOI: 10.3390/ijerph20105776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/03/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023]
Abstract
We assessed the disinfection efficacy of an ozone generator prototype in ambulances used to transport patients with coronavirus disease (COVID-19). This research consisted of three stages: in vitro tests using microbial indicators, such as Candida albicans, Escherichia coli, Staphylococcus aureus and Salmonella phage, which were experimentally inoculated onto polystyrene crystal surfaces within a 23 m3 enclosure. They were then exposed to ozone at a 25 ppm concentration using the ozone generator (Tecnofood SAC) portable prototype, and the decimal reduction time (D) was estimated for each indicator. The second stage involved the experimental inoculation of the same microbial indicators on a variety of surfaces inside conventional ambulances. The third stage consisted of exploratory field testing in ambulances used to transport patients with suspected COVID-19. During the second and third stages, samples were collected by swabbing different surfaces before and after 25 ppm ozonisation for 30 min. Results suggested that ozone was most effective on Candida albicans (D = 2.65 min), followed by Escherichia coli (D = 3.14 min), Salmonella phage (D = 5.01 min) and Staphylococcus aureus (D = 5.40 min). Up to 5% of the microbes survived following ozonisation of conventional ambulances. Of the 126 surface samples collected from ambulances transporting patients with COVID-19, 7 were positive (5.6%) for SARS-related coronavirus as determined on reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Ozone exposure from the ozone generator prototype inside ambulances at a concentration of 25 ppm for 30 min can eliminate gram positive and negative bacteria, yeasts, and viruses.
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Affiliation(s)
- Miguel Alejandro Gómez-Castillo
- Laboratorio de Microbiología de Alimentos, Facultad de Industrias Alimentarias, Universidad Nacional Agraria La Molina, Lima 15024, Peru
| | | | - Kevin Reátegui-Ochoa
- Laboratorio de Microbiología de Alimentos, Facultad de Industrias Alimentarias, Universidad Nacional Agraria La Molina, Lima 15024, Peru
| | | | - Marcial Silva-Jaimes
- Laboratorio de Microbiología de Alimentos, Facultad de Industrias Alimentarias, Universidad Nacional Agraria La Molina, Lima 15024, Peru
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5
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Golubova A, Lanekoff I. Surface sampling capillary electrophoresis-mass spectrometry for a direct chemical characterization of tissue and blood samples. Electrophoresis 2023; 44:387-394. [PMID: 36330562 PMCID: PMC10107203 DOI: 10.1002/elps.202200183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 10/24/2022] [Accepted: 10/26/2022] [Indexed: 11/06/2022]
Abstract
Capillary electrophoresis (CE) is a powerful separation tool for non-targeted analysis of chemically complex samples, such as blood, urine, and tissue. However, traditionally CE requires samples in solution for analysis, which limits information on analyte distribution and heterogeneity in tissue. The recent development of surface sampling CE-mass spectrometry (SS-CE-MS) brings these advantages of CE to solid samples and enables chemical mapping directly from the tissue surface without laborious sample preparation. Here, we describe developments of SS-CE-MS to increase reproducibility and stability for metabolite, lipid, and protein extraction from tissue sections and dried blood spots. Additionally, we report the first electrokinetic sequential sample injection for high throughput analysis. We foresee that the wide molecular coverage from a distinct tissue region in combination with higher throughput will provide novel information on biological function and dysfunction.
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Affiliation(s)
| | - Ingela Lanekoff
- Department of Chemistry-BMC, Uppsala University, Uppsala, Sweden
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6
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Cantú VJ, Salido RA, Huang S, Rahman G, Tsai R, Valentine H, Magallanes CG, Aigner S, Baer NA, Barber T, Belda-Ferre P, Betty M, Bryant M, Casas Maya M, Castro-Martínez A, Chacón M, Cheung W, Crescini ES, De Hoff P, Eisner E, Farmer S, Hakim A, Kohn L, Lastrella AL, Lawrence ES, Morgan SC, Ngo TT, Nouri A, Plascencia A, Ruiz CA, Sathe S, Seaver P, Shwartz T, Smoot EW, Ostrander RT, Valles T, Yeo GW, Laurent LC, Fielding-Miller R, Knight R. SARS-CoV-2 Distribution in Residential Housing Suggests Contact Deposition and Correlates with Rothia sp. mSystems 2022; 7:e0141121. [PMID: 35575492 PMCID: PMC9239251 DOI: 10.1128/msystems.01411-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/20/2022] [Indexed: 11/20/2022] Open
Abstract
Monitoring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on surfaces is emerging as an important tool for identifying past exposure to individuals shedding viral RNA. Our past work demonstrated that SARS-CoV-2 reverse transcription-quantitative PCR (RT-qPCR) signals from surfaces can identify when infected individuals have touched surfaces and when they have been present in hospital rooms or schools. However, the sensitivity and specificity of surface sampling as a method for detecting the presence of a SARS-CoV-2 positive individual, as well as guidance about where to sample, has not been established. To address these questions and to test whether our past observations linking SARS-CoV-2 abundance to Rothia sp. in hospitals also hold in a residential setting, we performed a detailed spatial sampling of three isolation housing units, assessing each sample for SARS-CoV-2 abundance by RT-qPCR, linking the results to 16S rRNA gene amplicon sequences (to assess the bacterial community at each location), and to the Cq value of the contemporaneous clinical test. Our results showed that the highest SARS-CoV-2 load in this setting is on touched surfaces, such as light switches and faucets, but a detectable signal was present in many untouched surfaces (e.g., floors) that may be more relevant in settings, such as schools where mask-wearing is enforced. As in past studies, the bacterial community predicts which samples are positive for SARS-CoV-2, with Rothia sp. showing a positive association. IMPORTANCE Surface sampling for detecting SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is increasingly being used to locate infected individuals. We tested which indoor surfaces had high versus low viral loads by collecting 381 samples from three residential units where infected individuals resided, and interpreted the results in terms of whether SARS-CoV-2 was likely transmitted directly (e.g., touching a light switch) or indirectly (e.g., by droplets or aerosols settling). We found the highest loads where the subject touched the surface directly, although enough virus was detected on indirectly contacted surfaces to make such locations useful for sampling (e.g., in schools, where students did not touch the light switches and also wore masks such that they had no opportunity to touch their face and then the object). We also documented links between the bacteria present in a sample and the SARS-CoV-2 virus, consistent with earlier studies.
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Affiliation(s)
- Victor J Cantú
- Department of Bioengineering, University of California San Diegogrid.266100.3, La Jolla, CA, USA
| | - Rodolfo A Salido
- Department of Bioengineering, University of California San Diegogrid.266100.3, La Jolla, CA, USA
| | - Shi Huang
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Gibraan Rahman
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Bioinformatics and Systems Biology Graduate Program, University of California San Diego, La Jolla, CA, USA
| | - Rebecca Tsai
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Holly Valentine
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
| | - Celestine G Magallanes
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
| | - Stefan Aigner
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Nathan A Baer
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Tom Barber
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Pedro Belda-Ferre
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Maryann Betty
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Rady Children's Hospital, San Diego, CA, USA
| | - MacKenzie Bryant
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Martín Casas Maya
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Anelizze Castro-Martínez
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Marisol Chacón
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Willi Cheung
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- San Diego State University, San Diego, CA, USA
| | - Evelyn S Crescini
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Peter De Hoff
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
| | - Emily Eisner
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Sawyer Farmer
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Abbas Hakim
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Laura Kohn
- Herbert Wertheim School of Public Health, University of California San Diegogrid.266100.3, La Jolla, CA, USA
| | - Alma L Lastrella
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Elijah S Lawrence
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Sydney C Morgan
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
| | - Toan T Ngo
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Alhakam Nouri
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Ashley Plascencia
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Christopher A Ruiz
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Shashank Sathe
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Phoebe Seaver
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Tara Shwartz
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Elizabeth W Smoot
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - R Tyler Ostrander
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Thomas Valles
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - Gene W Yeo
- Sanford Consortium of Regenerative Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA, USA
| | - Louise C Laurent
- Expedited COVID Identification Environment (EXCITE) Laboratory, Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
- Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
| | - Rebecca Fielding-Miller
- Herbert Wertheim School of Public Health, University of California San Diegogrid.266100.3, La Jolla, CA, USA
| | - Rob Knight
- Department of Bioengineering, University of California San Diegogrid.266100.3, La Jolla, CA, USA
- Department of Computer Science and Engineering, University of California San Diego, La Jolla, CA, USA
- Center for Microbiome Innovation, University of California San Diego, La Jolla, CA, USA
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7
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Nauta S, Huysmans P, Tuijthof GM, Eijkel GB, Poeze M, Siegel TP, Heeren RMA. Automated 3D Sampling and Imaging of Uneven Sample Surfaces with LA-REIMS. J Am Soc Mass Spectrom 2022; 33:111-122. [PMID: 34882413 PMCID: PMC8739836 DOI: 10.1021/jasms.1c00290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The analysis of samples with large height variations remains a challenge for mass spectrometry imaging (MSI), despite many technological advantages. Ambient sampling and ionization MS techniques allow for the molecular analysis of sample surfaces with height variations, but most techniques lack MSI capabilities. We developed a 3D MS scanner for the automated sampling and imaging of a 3D surface with laser-assisted rapid evaporative ionization mass spectrometry (LA-REIMS). The sample is moved automatically with a constant distance between the laser probe and sample surface in the 3D MS Scanner. The topography of the surface was scanned with a laser point distance sensor to define the MS measurement points. MS acquisition was performed with LA-REIMS using a surgical CO2 laser coupled to a qTOF instrument. The topographical scan and MS acquisition can be completed within 1 h using the 3D MS scanner for 300 measurement points on uneven samples with a spatial resolution of 2 mm in the top view, corresponding to 22.04 cm2. Comparison between the automated acquisition with the 3D MS scanner and manual acquisition by hand showed that the automation resulted in increased reproducibility between the measurement points. 3D visualizations of molecular distributions related to structural differences were shown for an apple, a marrowbone, and a human femoral head to demonstrate the imaging feasibility of the system. The developed 3D MS scanner allows for the automated sampling of surfaces with uneven topographies with LA-REIMS, which can be used for the 3D visualization of molecular distributions of these surfaces.
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Affiliation(s)
- Sylvia
P. Nauta
- Maastricht
MultiModal Molecular Imaging (M4i) Institute, Division of Imaging
Mass Spectrometry, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
- Department
of Orthopedic Surgery and Trauma Surgery, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands
| | - Pascal Huysmans
- Research
Engineering, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
| | - Gabriëlle
J. M. Tuijthof
- Research
Engineering, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
| | - Gert B. Eijkel
- Maastricht
MultiModal Molecular Imaging (M4i) Institute, Division of Imaging
Mass Spectrometry, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
| | - Martijn Poeze
- Department
of Surgery, Division of Trauma Surgery, Maastricht University Medical Center, P. Debyelaan 25, 6229 HX Maastricht, The Netherlands
- NUTRIM,
School for Nutrition and Translational Research in Metabolism, Maastricht University, Universiteitssingel 40, 6229 ER Maastricht, The Netherlands
| | - Tiffany Porta Siegel
- Maastricht
MultiModal Molecular Imaging (M4i) Institute, Division of Imaging
Mass Spectrometry, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
| | - Ron M. A. Heeren
- Maastricht
MultiModal Molecular Imaging (M4i) Institute, Division of Imaging
Mass Spectrometry, Maastricht University, Universiteitssingel 50, 6229ER Maastricht, The Netherlands
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8
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Salido RA, Cantú VJ, Clark AE, Leibel SL, Foroughishafiei A, Saha A, Hakim A, Nouri A, Lastrella AL, Castro-Martínez A, Plascencia A, Kapadia BK, Xia B, Ruiz CA, Marotz CA, Maunder D, Lawrence ES, Smoot EW, Eisner E, Crescini ES, Kohn L, Franco Vargas L, Chacón M, Betty M, Machnicki M, Wu MY, Baer NA, Belda-Ferre P, De Hoff P, Seaver P, Ostrander RT, Tsai R, Sathe S, Aigner S, Morgan SC, Ngo TT, Barber T, Cheung W, Carlin AF, Yeo GW, Laurent LC, Fielding-Miller R, Knight R. Analysis of SARS-CoV-2 RNA Persistence across Indoor Surface Materials Reveals Best Practices for Environmental Monitoring Programs. mSystems 2021;:e0113621. [PMID: 34726486 DOI: 10.1128/mSystems.01136-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Environmental monitoring in public spaces can be used to identify surfaces contaminated by persons with coronavirus disease 2019 (COVID-19) and inform appropriate infection mitigation responses. Research groups have reported detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on surfaces days or weeks after the virus has been deposited, making it difficult to estimate when an infected individual may have shed virus onto a SARS-CoV-2-positive surface, which in turn complicates the process of establishing effective quarantine measures. In this study, we determined that reverse transcription-quantitative PCR (RT-qPCR) detection of viral RNA from heat-inactivated particles experiences minimal decay over 7 days of monitoring on eight out of nine surfaces tested. The properties of the studied surfaces result in RT-qPCR signatures that can be segregated into two material categories, rough and smooth, where smooth surfaces have a lower limit of detection. RT-qPCR signal intensity (average quantification cycle [Cq]) can be correlated with surface viral load using only one linear regression model per material category. The same experiment was performed with untreated viral particles on one surface from each category, with essentially identical results. The stability of RT-qPCR viral signal demonstrates the need to clean monitored surfaces after sampling to establish temporal resolution. Additionally, these findings can be used to minimize the number of materials and time points tested and allow for the use of heat-inactivated viral particles when optimizing environmental monitoring methods. IMPORTANCE Environmental monitoring is an important tool for public health surveillance, particularly in settings with low rates of diagnostic testing. Time between sampling public environments, such as hospitals or schools, and notifying stakeholders of the results should be minimal, allowing decisions to be made toward containing outbreaks of coronavirus disease 2019 (COVID-19). The Safer At School Early Alert program (SASEA) (https://saseasystem.org/), a large-scale environmental monitoring effort in elementary school and child care settings, has processed >13,000 surface samples for SARS-CoV-2, detecting viral signals from 574 samples. However, consecutive detection events necessitated the present study to establish appropriate response practices around persistent viral signals on classroom surfaces. Other research groups and clinical labs developing environmental monitoring methods may need to establish their own correlation between RT-qPCR results and viral load, but this work provides evidence justifying simplified experimental designs, like reduced testing materials and the use of heat-inactivated viral particles.
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9
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Naylor CL, Davies B, Gopaldasani V. Quantitative skin exposure assessment of metals: A case study. Toxicol Lett 2021; 351:135-144. [PMID: 34500033 DOI: 10.1016/j.toxlet.2021.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/27/2021] [Accepted: 09/02/2021] [Indexed: 11/28/2022]
Abstract
This article provides guidance into the quantitative risk assessment of skin exposures to metals. The use of wipe sampling methodologies has been shown to be standardised and effective for skin exposure assessment to metals. However, there is a lack of guidance documents and frameworks available to evaluate the level of health risk to workers from skin exposures to metals. Adverse health effects from exposures to metals have been described in the literature (Fernández-Nieto et al. 2006; Herman et al. 2006; Kreiss et al. 1996). Monitoring of workplace exposures typically focuses on the assessment of respiratory exposures. To provide a safe workplace there is a need to ensure all routes of exposure are risk assessed and controlled. The goal of this article was to develop skin (surface) exposure limits to metals, using the construction industry as a test environment, to quantitatively assess worker health risk of skin exposures to metals. This research concluded it was not feasible to establish single quantitative skin exposure limits to metals due to the many assumptions surrounding dermal exposures. A range of acceptable exposure limits are presented.
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Affiliation(s)
- Carmen L Naylor
- School of Health and Society, University of Wollongong, Wollongong, Australia; Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia.
| | - Brian Davies
- School of Health and Society, University of Wollongong, Wollongong, Australia.
| | - Vinod Gopaldasani
- School of Health and Society, University of Wollongong, Wollongong, Australia.
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Paton S, Spencer A, Garratt I, Thompson KA, Dinesh I, Aranega-Bou P, Stevenson D, Clark S, Dunning J, Bennett A, Pottage T. Persistence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Virus and Viral RNA in Relation to Surface Type and Contamination Concentration. Appl Environ Microbiol 2021; 87:e0052621. [PMID: 33962986 DOI: 10.1128/AEM.00526-21] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The transmission of SARS-CoV-2 is likely to occur through a number of routes, including contact with contaminated surfaces. Many studies have used reverse transcription-PCR (RT-PCR) analysis to detect SARS-CoV-2 RNA on surfaces, but seldom has viable virus been detected. This paper investigates the viability over time of SARS-CoV-2 dried onto a range of materials and compares viability of the virus to RNA copies recovered and whether virus viability is concentration dependent. Viable virus persisted for the longest time on surgical mask material and stainless steel, with a 99.9% reduction in viability by 122 and 114 h, respectively. Viability of SARS-CoV-2 reduced the fastest on a polyester shirt, with a 99.9% reduction within 2.5 h. Viability on the bank note was reduced second fastest, with 99.9% reduction in 75 h. RNA on all surfaces exhibited a 1-log reduction in genome copy number recovery over 21 days. The findings show that SARS-CoV-2 is most stable on nonporous hydrophobic surfaces. RNA is highly stable when dried on surfaces, with only 1-log reduction in recovery over 3 weeks. In comparison, SARS-CoV-2 viability reduced more rapidly, but this loss in viability was found to be independent of starting concentration. Expected levels of SARS-CoV-2 viable environmental surface contamination would lead to undetectable levels within 2 days. Therefore, when RNA is detected on surfaces, it does not directly indicate the presence of viable virus, even at low cycle threshold values. IMPORTANCE This study shows the impact of material type on the viability of SARS-CoV-2 on surfaces. It demonstrates that the decay rate of viable SARS-CoV-2 is independent of starting concentration. However, RNA shows high stability on surfaces over extended periods. This has implications for interpretation of surface sampling results using RT-PCR to determine the possibility of viable virus from a surface, where RT-PCR is not an appropriate technique to determine viable virus. Unless sampled immediately after contamination, it is difficult to align RNA copy numbers to quantity of viable virus on a surface.
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11
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Madsen AM, Phan HUT, Laursen M, White JK, Uhrbrand K. Evaluation of Methods for Sampling of Staphylococcus aureus and Other Staphylococcus Species from Indoor Surfaces. Ann Work Expo Health 2021; 64:1020-1034. [PMID: 32968799 PMCID: PMC7750978 DOI: 10.1093/annweh/wxaa080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/03/2020] [Accepted: 07/14/2020] [Indexed: 11/26/2022] Open
Abstract
Objectives Methicillin-resistant Staphylococcus aureus (MRSA) is an increasing public and occupational health concern. As transmission of MRSA can occur via contact with fomites, it is crucial to have sensitive methods for sampling of bacteria. The overall aim of this study was to obtain knowledge about methods and strategies for quantitative sampling Staphylococcus species on surfaces. Methods The study was designed as a comparative sampling experiment with different samplers [dipslide (two agar types), swabs (three brands, used wet and dry, and elution from swabs or plate diluted)] on smooth stainless steel surfaces spiked with MRSA and methicillin-sensitive S. aureus (MSSA). Furthermore, bacteria sampled from indoor surfaces with frequent or infrequent contact with hands were quantified and identified using matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). Results Pre-moistened swabs in combination with dilution plating and dipslides were more sensitive than dry swabs. For recovery of MRSA and MSSA from surfaces with eSwabs, at least 0.3–100 CFU MRSA cm−2 and 5.3–8.6 CFU MSSA cm−2 should be present. The sensitivities of pre-moistened eSwabs were approximately 10-fold higher than those of dipslides and pre-moistened viscose and cotton swabs. The variation in concentrations of Staphylococcus species in replicate sampling of adjacent squares on indoor surfaces was higher for surfaces frequently touched by hands than for surfaces infrequently touched. In total 16 different Staphylococcus species were identified, and S. aureus was found only in 2 of 66 surface samples. A considerable overlap was found between species in replicate sampling within an environment and between the air and surfaces within an environment. Conclusions Pre-moistened eSwabs in combination with dilution plating were found to be the best method for surface sampling of MSSA and MRSA. The method can be used for assessing the risk of exposure and transmission of MRSA from environmental surfaces. To obtain a reliable measure of concentrations and the presence of Staphylococccus species a higher number of samples should be taken from surfaces with hand contact than from surfaces dominated by sedimented bacteria.
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Affiliation(s)
- Anne Mette Madsen
- National Research Centre for the Working Environment, Lersø Parkallé, Copenhagen Ø, Denmark
| | - Hoang U T Phan
- National Research Centre for the Working Environment, Lersø Parkallé, Copenhagen Ø, Denmark
| | - Mathias Laursen
- National Research Centre for the Working Environment, Lersø Parkallé, Copenhagen Ø, Denmark
| | - John K White
- National Research Centre for the Working Environment, Lersø Parkallé, Copenhagen Ø, Denmark
| | - Katrine Uhrbrand
- National Research Centre for the Working Environment, Lersø Parkallé, Copenhagen Ø, Denmark
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12
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Parker CW, Singh N, Tighe S, Blachowicz A, Wood JM, Seuylemezian A, Vaishampayan P, Urbaniak C, Hendrickson R, Laaguiby P, Clark K, Clement BG, O'Hara NB, Couto-Rodriguez M, Bezdan D, Mason CE, Venkateswaran K. End-to-End Protocol for the Detection of SARS-CoV-2 from Built Environments. mSystems 2020; 5:e00771-20. [PMID: 33024053 PMCID: PMC7542562 DOI: 10.1128/msystems.00771-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/22/2020] [Indexed: 12/19/2022] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019, is a respiratory virus primarily transmitted person to person through inhalation of droplets or aerosols, laden with viral particles. However, as recent studies have shown, virions can remain infectious for up to 72 h on surfaces, which can lead to transmission through contact. Thus, a comprehensive study was conducted to determine the efficiency of protocols to recover SARS-CoV-2 from surfaces in built environments. This end-to-end (E2E) study showed that the effective combination for monitoring SARS-CoV-2 on surfaces includes using an Isohelix swab collection tool, DNA/RNA Shield as a preservative, an automated system for RNA extraction, and reverse transcriptase quantitative PCR (RT-qPCR) as the detection assay. Using this E2E approach, this study showed that, in some cases, noninfectious viral fragments of SARS-CoV-2 persisted on surfaces for as long as 8 days even after bleach treatment. Additionally, debris associated with specific built environment surfaces appeared to inhibit and negatively impact the recovery of RNA; Amerstat demonstrated the highest inhibition (>90%) when challenged with an inactivated viral control. Overall, it was determined that this E2E protocol required a minimum of 1,000 viral particles per 25 cm2 to successfully detect virus from test surfaces. Despite our findings of viral fragment longevity on surfaces, when this method was employed to evaluate 368 samples collected from various built environmental surfaces, all samples tested negative, indicating that the surfaces were either void of virus or below the detection limit of the assay.IMPORTANCE The ongoing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (the virus responsible for coronavirus disease 2019 [COVID-19]) pandemic has led to a global slowdown with far-reaching financial and social impacts. The SARS-CoV-2 respiratory virus is primarily transmitted from person to person through inhalation of infected droplets or aerosols. However, some studies have shown that virions can remain infectious on surfaces for days and can lead to human infection from contact with infected surfaces. Thus, a comprehensive study was conducted to determine the efficiency of protocols to recover SARS-CoV-2 from surfaces in built environments. This end-to-end study showed that the effective combination for monitoring SARS-CoV-2 on surfaces required a minimum of 1,000 viral particles per 25 cm2 to successfully detect virus from surfaces. This comprehensive study can provide valuable information regarding surface monitoring of various materials as well as the capacity to retain viral RNA and allow for effective disinfection.
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Affiliation(s)
- Ceth W Parker
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Nitin Singh
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Scott Tighe
- Vermont Integrative Genomics Resource, Larner College of Medicine, The University of Vermont, Burlington, Vermont, USA
| | - Adriana Blachowicz
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Jason M Wood
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Arman Seuylemezian
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Parag Vaishampayan
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Camilla Urbaniak
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
- ZIN Technologies Inc., Middleburg Heights, Ohio, USA
| | - Ryan Hendrickson
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Pheobe Laaguiby
- Vermont Integrative Genomics Resource, Larner College of Medicine, The University of Vermont, Burlington, Vermont, USA
| | - Kevin Clark
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Brian G Clement
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
| | - Niamh B O'Hara
- Biotia, New York, New York, USA
- SUNY Downstate Health Sciences University, Brooklyn, New York, USA
| | | | - Daniela Bezdan
- Weill Medical College of Cornell University, New York, New York, USA
- Institute of Medical Virology and Epidemiology of Viral Diseases, University Hospital, Tubingen, Germany
| | | | - Kasthuri Venkateswaran
- NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
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Aktas YD, Reeslev M, Altamirano H, May N, D’Ayala D. Normal background levels of air and surface mould reserve in English residential building stock: a preliminary study towards benchmarks based on NAHA measurements. UCL Open Environ 2020; 2:e005. [PMID: 37229291 PMCID: PMC10171414 DOI: 10.14324/111.444/ucloe.000005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 02/13/2020] [Indexed: 05/27/2023]
Abstract
This paper reports results obtained from a surface (both visually clean and dirty/dusty surfaces) and active (aggressive or activated) air testing scheme on 140 residential rooms in England, without visible water damage or mould growth, along with a few rooms with visible mould growth/water damage tested for comparison purposes. The aim was to establish normal background levels of mould in non-water-damaged interiors to benchmark a 'normal' indoor environment, and in turn when there is a need for further investigation, and, possibly, remediation. Air and surface mould was quantified based on the activity of β-N-acetylhexosaminidase (EC 3.2.1.52; NAHA). The obtained readings showed a log-normal distribution. Ninety-eight percent of the samples obtained from visually clean surfaces were equal to or less than 25 relative fluorescence units (RFU), which is suggested to be the higher bound for the range which can be used as a success criterion for surface cleaning/remediation. Of samples obtained from visually dirty/dusty surfaces, around 98% were below 450 RFU, which is suggested to define the lower-bound for abnormally high levels of mould, rare even on dirty/dusty surfaces. Similarly, around 98% of the air samples were found to have 1700 RFU or below. Values above 1700 RFU are therefore deemed unlikely in a non-problem indoor environment and can be indicative of a possible problem inducing mould growth. The samples with values below 1700 were further divided into three proposed sub-categories. Finally, the obtained RFU values and the suggested benchmarks were compared to those obtained from 17 non-residential indoor environments tested previously in Copenhagen, and the benchmarks that are currently used in Danish national standards, and they were both found to be highly congruent, suggesting that local climate regimes and room functions might not be as influential on indoor mould levels as commonly thought, or that the nuances between England and Denmark in terms of these factors are not strong enough to lead to sizable changes in the typical indoor mould levels in these countries' building stocks.
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Affiliation(s)
- Yasemin Didem Aktas
- University College London (UCL), Department of Civil, Environmental and Geomatic Engineering (CEGE), Epicentre Research Group, London WC1E 6DE, UK
- UK Centre for Moisture in Buildings (UKCMB), University College London, London WC1H 0NN, UK
| | - Morten Reeslev
- Mycometer A/S, Dr Neergaards Vej 3, 2970 Hørsholm, Denmark
| | - Hector Altamirano
- UK Centre for Moisture in Buildings (UKCMB), University College London, London WC1H 0NN, UK
- University College London (UCL), Institute of Environmental Design and Engineering (IEDE), London WC1H 0NN, UK
| | - Neil May
- UK Centre for Moisture in Buildings (UKCMB), University College London, London WC1H 0NN, UK
| | - Dina D’Ayala
- University College London (UCL), Department of Civil, Environmental and Geomatic Engineering (CEGE), Epicentre Research Group, London WC1E 6DE, UK
- UK Centre for Moisture in Buildings (UKCMB), University College London, London WC1H 0NN, UK
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Bobal M, Witte AK, Mester P, Fister S, Schoder D, Rossmanith P. A Novel Method for Sampling and Long-Term Monitoring of Microbes That Uses Stickers of Plain Paper. Appl Environ Microbiol 2019; 85:e00766-19. [PMID: 31126944 DOI: 10.1128/AEM.00766-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 04/24/2019] [Indexed: 11/20/2022] Open
Abstract
Detection of pathogens is crucial in food production areas. While it is well established, swabbing as a state-of-the-art sampling method offers several drawbacks with respect to yield, standardization, overall handling, and long-term monitoring. This led us to develop and evaluate a method that is easier to use at a lower cost and that should be at least as sensitive. After evaluating sundry promising materials, we tested text-marking paper stickers for their suitability to take up and release Listeria monocytogenes with their nonsticky paper side over a 14-day time period using quantitative PCR. The recovery rate was similar to that in previous studies using conventional swabs, and we also confirmed the feasibility of pooling besides resilience to cleansing and disinfection. In a proof-of-concept experiment that sampled several locations, such as door handles, the occurrences of L. monocytogenes and Escherichia coli were determined. The results suggest that the presented sticker system might offer a promising cost-effective alternative sampling system with improved handling characteristics.IMPORTANCE As a ubiquitous bacterium, Listeria monocytogenes has a propensity to enter food production areas inadvertently via fomites such as door handles and switches. While the bacterium might not be in direct contact with the food products, knowing the microbial status of the surroundings is essential for risk assessment. Our investigation into a novel quantitative PCR (qPCR)-based sampling system with the highest sensitivity and ability to monitor over long periods of time, yet based on paper, proved to be cost-effective and reasonably convenient to handle.
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15
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Tuomi T, Kilpikari J, Hartonen M, Kämppi R, Lallukka H. Filter Cassette Method for Analyzing Man-Made Vitreous Fibers Settled on Surfaces. Int J Environ Res Public Health 2019; 16:E1256. [PMID: 30970535 PMCID: PMC6480609 DOI: 10.3390/ijerph16071256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/03/2019] [Accepted: 04/05/2019] [Indexed: 11/18/2022]
Abstract
A new method was developed to analyze the surface count of fibers in a variety of environments. The method entails sampling surfaces with the help of suction to a filter cassette holder containing a cellulose filter. The filters were collapsed using microwave digestion in dilute acid, and the fibers filtered to polycarbonate filters, gilded, and analyzed by scanning electron microscopy (SEM). The method was compared to traditional gel tape sampling as described in International Standards Organization (ISO) standard 16000-27, following analysis with phase contrast microscopy. The methods were compared in industrial environments and in office-type environments, with the concentration range studied spanning from 0.1 to 100,000 fibers/cm². The methods yielded similar results (p < 0.05) in concentrations from 100 to 10,000 cfu/cm², while the filter cassette method gave systematically higher results in high concentrations (>10,000 cfu/cm²) as well as in all office-type environments studied, where the fiber count ranged from 0.1 to 20 fibers/cm². Consequently, we recommend using the new method in working environments where the surface count is more than 100 fibers/cm², as well as in office-type environments where the fiber count is below 10 fibers/cm². It should be noted, however, that a similar limit of quantitation as with the gel tape method (0.1 fibers/cm²) requires sampling a minimum area of 100 × 100 cm² with the fiber cassette method. Using the filter cassette method will require new guide values to be formed for office-type environments, since the results are higher than with the gel tape method. Alternatively, if present guide values or limit values are to be used with the filter cassette method, conventions as to which fiber sizes to count should be set, since SEM analysis in any case will allow for including a larger size range than phase contrast microscopy (PM). We, however, recommend against such an approach, since fibers less than 1 µm in width may not be less harmful by inhalation than larger fibers.
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Affiliation(s)
- Tapani Tuomi
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 B, P.O. Box 40, Työterveyslaitos, FI-00032 Helsinki, Finland.
| | - Jyrki Kilpikari
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 B, P.O. Box 40, Työterveyslaitos, FI-00032 Helsinki, Finland.
| | - Minna Hartonen
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 B, P.O. Box 40, Työterveyslaitos, FI-00032 Helsinki, Finland.
| | - Reima Kämppi
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 B, P.O. Box 40, Työterveyslaitos, FI-00032 Helsinki, Finland.
| | - Heli Lallukka
- Finnish Institute of Occupational Health, Topeliuksenkatu 41 B, P.O. Box 40, Työterveyslaitos, FI-00032 Helsinki, Finland.
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16
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Kocurek KI, Griffiths RL, Cooper HJ. Ambient ionisation mass spectrometry for in situ analysis of intact proteins. J Mass Spectrom 2018; 53:565-578. [PMID: 29607564 PMCID: PMC6001466 DOI: 10.1002/jms.4087] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 05/05/2023]
Abstract
Ambient surface mass spectrometry is an emerging field which shows great promise for the analysis of biomolecules directly from their biological substrate. In this article, we describe ambient ionisation mass spectrometry techniques for the in situ analysis of intact proteins. As a broad approach, the analysis of intact proteins offers unique advantages for the determination of primary sequence variations and posttranslational modifications, as well as interrogation of tertiary and quaternary structure and protein-protein/ligand interactions. In situ analysis of intact proteins offers the potential to couple these advantages with information relating to their biological environment, for example, their spatial distributions within healthy and diseased tissues. Here, we describe the techniques most commonly applied to in situ protein analysis (liquid extraction surface analysis, continuous flow liquid microjunction surface sampling, nano desorption electrospray ionisation, and desorption electrospray ionisation), their advantages, and limitations and describe their applications to date. We also discuss the incorporation of ion mobility spectrometry techniques (high field asymmetric waveform ion mobility spectrometry and travelling wave ion mobility spectrometry) into ambient workflows. Finally, future directions for the field are discussed.
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Affiliation(s)
- Klaudia I. Kocurek
- School of BiosciencesUniversity of BirminghamEdgbastonBirminghamB15 2TTUK
| | - Rian L. Griffiths
- School of BiosciencesUniversity of BirminghamEdgbastonBirminghamB15 2TTUK
| | - Helen J. Cooper
- School of BiosciencesUniversity of BirminghamEdgbastonBirminghamB15 2TTUK
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Blachere FM, Lindsley WG, Weber AM, Beezhold DH, Thewlis RE, Mead KR, Noti JD. Detection of an avian lineage influenza A(H7N2) virus in air and surface samples at a New York City feline quarantine facility. Influenza Other Respir Viruses 2018; 12:613-622. [PMID: 29768714 PMCID: PMC6086858 DOI: 10.1111/irv.12572] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/02/2018] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND In December 2016, an outbreak of low pathogenicity avian influenza (LPAI) A(H7N2) occurred in cats at a New York City animal shelter and quickly spread to other shelters in New York and Pennsylvania. The A(H7N2) virus also spread to an attending veterinarian. In response, 500 cats were transferred from these shelters to a temporary quarantine facility for continued monitoring and treatment. OBJECTIVES The objective of this study was to assess the occupational risk of A(H7N2) exposure among emergency response workers at the feline quarantine facility. METHODS Aerosol and surface samples were collected from inside and outside the isolation zones of the quarantine facility. Samples were screened for A(H7N2) by quantitative RT-PCR and analyzed in embryonated chicken eggs for infectious virus. RESULTS H7N2 virus was detected by RT-PCR in 28 of 29 aerosol samples collected in the high-risk isolation (hot) zone with 70.9% on particles with aerodynamic diameters >4 μm, 27.7% in 1-4 μm, and 1.4% in <1 μm. Seventeen of 22 surface samples from the high-risk isolation zone were also H7N2 positive with an average M1 copy number of 1.3 × 103 . Passage of aerosol and surface samples in eggs confirmed that infectious virus was present throughout the high-risk zones in the quarantine facility. CONCLUSIONS By measuring particle size, distribution, and infectivity, our study suggests that the A(H7N2) virus had the potential to spread by airborne transmission and/or direct contact with viral-laden fomites. These results warranted continued A(H7N2) surveillance and transmission-based precautions during the treatment and care of infected cats.
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Affiliation(s)
- Francoise M Blachere
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
| | - William G Lindsley
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
| | - Angela M Weber
- Disaster Science Responder Research Program, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Donald H Beezhold
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
| | - Robert E Thewlis
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
| | - Kenneth R Mead
- Engineering and Physical Hazards Branch, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH, USA
| | - John D Noti
- Allergy and Clinical Immunology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
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Kouassi S, Catto C, Ostiguy C, L'Espérance G, Kroeger J, Debia M. Exposure Assessment in a Single-Walled Carbon Nanotube Primary Manufacturer. Ann Work Expo Health 2017; 61:260-266. [PMID: 28395348 DOI: 10.1093/annweh/wxw017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 12/02/2016] [Indexed: 11/12/2022] Open
Abstract
Objectives This study was aimed at documenting and characterizing occupational exposure to single-walled carbon nanotubes (SWCNTs) generated in a primary manufacturing plant. It also compared various strategies of exposure monitoring. Methods A 6-day measurement protocol was scheduled (D1-D6) including both (i) quasi-personal monitoring with an array of direct reading instruments (DRIs) and (ii) offline electron microscopy analyses of surface and breathing zone filter-based samples. The first step (D1 and D2) consisted of contamination screenings resulting from the various SWCNT production tasks using a multimetric approach. Surface sampling was also carried out to assess workplace cross-contamination. The second step (D3-D6) focused on the exposure monitoring during recovery/cleaning task, by comparing three personal elemental carbon (EC) measurements [respirable EC using a cyclone following the NIOSH 5040 method (REC-CYC), respirable and thoracic EC using parallel particle impactors [REC-PPI and TEC-PPI, respectively)] and gravimetric mass concentration measurements. Results DustTrak DRX and electrical low-pressure impactor measurements indicated that particles were released during weighing, transferring, and recovery/cleaning tasks of the manufacturing process. Electron microscopy revealed the presence of agglomerated SWCNTs only during the recovery/cleaning task. REC-CYC concentrations remained under the limits of quantification; REC-PPI showed levels up to 58 µg m-3; and TEC-PPI ranged from 40 to 70 µg m-3. Ratios calculated between gravimetric measurements and estimated DustTrak mass concentrations ranged from 2.8 to 4.9. Cross-contamination appeared to be limited since SWCNTs was only found on surface samples collected close to the reactor in the production room. Conclusions This case study showed that the DustTrak DRX should be the preferred device among DRIs to identify potential exposure to SWCNTs. However, there is a risk of false positive since it is a non-specific instrument; therefore, the actual release of SWCNTs must be confirmed with scanning electron microscopy/transmission electron microscopy analyses. Besides, using EC measurements as a proxy for SWCNT exposure assessments, as suggested by the NIOSH, is still challenging since interferences can occur with other EC sources such as carbon black, which is also present in the workplace.
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Affiliation(s)
- Serge Kouassi
- Institut de recherche en santé publique de l'Université de Montréal (IRSPUM), Department of Environmental and Occupational Health, École de santé publique, Université de Montréal, PO Box 6128, Main Station, Montréal, Québec H3C3J7, Canada
| | - Cyril Catto
- Institut de recherche en santé publique de l'Université de Montréal (IRSPUM), Department of Environmental and Occupational Health, École de santé publique, Université de Montréal, PO Box 6128, Main Station, Montréal, Québec H3C3J7, Canada
| | - Claude Ostiguy
- Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), 505, Boul. de Maisonneuve Ouest, Montréal, Québec H3A 3C2, Canada
| | - Gilles L'Espérance
- École Polytechnique de Montréal, PO Box 6079, Main Station, Montréal, Québec H3C3A7, Canada
| | - Jens Kroeger
- Raymor Industries Inc., 3765 Rue la Vérendrye, Boisbriand, Québec QC J7H 1R8, Canada
| | - Maximilien Debia
- Institut de recherche en santé publique de l'Université de Montréal (IRSPUM), Department of Environmental and Occupational Health, École de santé publique, Université de Montréal, PO Box 6128, Main Station, Montréal, Québec H3C3J7, Canada
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19
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Abstract
Surface wipe sampling in the occupational environment is a technique widely used by industrial hygienists. Although several organizations have promulgated standards for sampling lead and other metals, uncertainty still exists when trying to determine an appropriate wipe sampling strategy and how to interpret sampling results. Investigators from the National Institute for Occupational Safety and Health (NIOSH) Health Hazard Evaluation Program have used surface wipe sampling as part of their exposure assessment sampling strategies in a wide range of workplaces. This article discusses wipe sampling for measuring lead on surfaces in three facilities: (1) a battery recycling facility; (2) a firing range and gun store; and (3) an electronic scrap recycling facility. We summarize our findings from the facilities and what we learned by integrating wipe sampling into our sampling plan. Wiping sampling demonstrated lead in non-production surfaces in all three workplaces and that the potential that employees were taking lead home to their families existed. We also found that the presence of metals such as tin can interfere with the colorimetric results. We also discuss the advantages and disadvantages of colorimetric analysis of surface wipe samples and the challenges we faced when interpreting wipe sampling results.
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Affiliation(s)
- Catherine Beaucham
- a Hazard Evaluations and Technical Assistance Branch, Division of Surveillance, Hazard Evaluations and Field Studies , National Institute for Occupational Safety and Health , Cincinnati , Ohio
| | - Diana Ceballos
- b Department of Environmental Health , Harvard T.H. Chan School of Public Health , Boston , Massachusetts
| | - Bradley King
- c Western States Division , National Institute for Occupational Safety and Health , Denver , Colorado
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20
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Abstract
Human noroviruses are a leading cause of epidemic and sporadic gastroenteritis worldwide. Because most infections are either spread directly via the person-to-person route or indirectly through environmental surfaces or food, contaminated fomites and inanimate surfaces are important vehicles for the spread of the virus during norovirus outbreaks. We developed and evaluated a protocol using macrofoam swabs for the detection and typing of human noroviruses from hard surfaces. Compared with fiber-tipped swabs or antistatic wipes, macrofoam swabs allow virus recovery (range 1.2-33.6%) from toilet seat surfaces of up to 700 cm2. The protocol includes steps for the extraction of the virus from the swabs and further concentration of the viral RNA using spin columns. In total, 127 (58.5%) of 217 swab samples that had been collected from surfaces in cruise ships and long-term care facilities where norovirus gastroenteritis had been reported tested positive for GII norovirus by RT-qPCR. Of these 29 (22.8%) could be successfully genotyped. In conclusion, detection of norovirus on environmental surfaces using the protocol we developed may assist in determining the level of environmental contamination during outbreaks as well as detection of virus when clinical samples are not available; it may also facilitate monitoring of effectiveness of remediation strategies.
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Affiliation(s)
- Geun Woo Park
- Division of Viral Diseases, Centers for Disease Control and Prevention;
| | - Preeti Chhabra
- Division of Viral Diseases, Centers for Disease Control and Prevention
| | - Jan Vinjé
- Division of Viral Diseases, Centers for Disease Control and Prevention
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21
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Abstract
Cross-contamination is an increasingly important risk factor in food safety. Cleaning and disinfection regimens are essential components in its prevention but need to be validated, monitored, and verified. This in turn requires the implementation of protocols for surface sampling and the assessment of residual contamination. Visual assessment although widely used, in isolation, is ineffective but can be useful as part of an integrated approach. Microbial and nonmicrobial methods of sampling and testing are compared. Nonmicrobial assessment methods, especially ATP, are effective at monitoring residual surface soil. Traditional specific, and nonspecific, microbial methods indicate residual microbial contamination but not surface soil. Recent advances in molecular microbial methods and bioluminogenic tests are discussed. There is no single ideal surface test method and how, when, and where to sample are discussed within the framework of suggested guidelines, an integrated approach, and the use of trend analysis.
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22
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Shahrasbi AA, Afshar M, Shokraneh F, Monji F, Noroozi M, Ebrahimi-Khojin M, Madani SF, Ahadi-Barzoki M, Rajabi M. Risks to health professionals from hazardous drugs in Iran: a pilot study of understanding of healthcare team to occupational exposure to cytotoxics. EXCLI J 2014; 13:491-501. [PMID: 26417276 PMCID: PMC4464082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 05/08/2014] [Indexed: 11/05/2022]
Abstract
Ongoing concerns exist regarding the dangers inherent when handling cytotoxics, particularly drugs which are in parenteral formulations. On occasions, nurses and medical doctors have been preparing and administrating these drugs in the open spaces of wards in the absence of suitable personal protective equipment (PPE) and safety cabinets. To explore further into the severity of occupational hazards, we conducted our research in order to evaluate the healthcare's understanding of occupational exposure to cytotoxics and occurrence of any side effects. A cross-sectional study using a self-administered questionnaire was distributed amongst oncology nurses in nine specialized cancer centers in Tehran. The questionnaire was based on most reputable international guidelines, aiming to evaluate the attitude, knowledge and safe practices of nurses' handling cytotoxic drugs. The gathered data and reported side effects were compared between "oncology/hematology" and "non-oncology" participants. The majority of nurses from oncology wards were aware of the potential hazards associated with handling of chemotherapy and reported high levels of compliance with the use of PPE during reconstitution of antineoplastic agents. Almost all nurses reported the use of a safety cabinet during preparation, however only 55 % reported that they have annual medical checkups and 45 % reported having received specialized training. This work was also to evaluate the experimental procedures as well as cleaning solutions used to reduce the level exposure. While the level of knowledge about antineoplastic agents is high among nurses, along with the level of PPE use, medical surveillance and employee training seems to be lagging behind.
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Affiliation(s)
| | - Minoo Afshar
- Department of Pharmaceutics, Islamic Azad University, Tehran, Iran
| | - Farnaz Shokraneh
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
| | - Faezeh Monji
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
| | - Mahjabin Noroozi
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
| | - Maryam Ebrahimi-Khojin
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
| | - Seyed Farzam Madani
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
| | - Mehdi Ahadi-Barzoki
- Department of Clinical Pharmacy, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Mehdi Rajabi
- Department of Clinical Pharmacy, Islamic Azad University, Pharmaceutical Sciences Branch, Tehran, Iran
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23
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Teshale EH, Painter J, Burr GA, Mead P, Wright SV, Cseh LF, Zabrocki R, Collins R, Kelley KA, Hadler JL, Swerdlow DL. Environmental sampling for spores of Bacillus anthracis. Emerg Infect Dis 2002; 8:1083-7. [PMID: 12396920 PMCID: PMC2730287 DOI: 10.3201/eid0810.020398] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
On November 11, 2001, following the bioterrorism-related anthrax attacks, the U.S. Postal Service collected samples at the Southern Connecticut Processing and Distribution Center; all samples were negative for Bacillus anthracis. After a patient in Connecticut died from inhalational anthrax on November 19, the center was sampled again on November 21 and 25 by using dry and wet swabs. All samples were again negative for B. anthracis. On November 28, guided by information from epidemiologic investigation, we sampled the site extensively with wet wipes and surface vacuum sock samples (using HEPA vacuum). Of 212 samples, 6 (3%) were positive, including one from a highly contaminated sorter. Subsequently B. anthracis was also detected in mail-sorting bins used for the patient's carrier route. These results suggest cross-contaminated mail as a possible source of anthrax for the inhalational anthrax patient in Connecticut. In future such investigations, extensive sampling guided by epidemiologic data is imperative.
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Affiliation(s)
- Eyasu H Teshale
- Centers for Desease Control and Prevention , Atlanta, Georgia 30333, USA.
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24
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Sanderson WT, Hein MJ, Taylor L, Curwin BD, Kinnes GM, Seitz TA, Popovic T, Holmes HT, Kellum ME, McAllister SK, Whaley DN, Tupin EA, Walker T, Freed JA, Small DS, Klusaritz B, Bridges JH. Surface sampling methods for Bacillus anthracis spore contamination. Emerg Infect Dis 2002; 8:1145-51. [PMID: 12396930 PMCID: PMC2730285 DOI: 10.3201/eid0810.020382] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
During an investigation conducted December 17-20, 2001, we collected environmental samples from a U.S. postal facility in Washington, D.C., known to be extensively contaminated with Bacillus anthracis spores. Because methods for collecting and analyzing B. anthracis spores have not yet been validated, our objective was to compare the relative effectiveness of sampling methods used for collecting spores from contaminated surfaces. Comparison of wipe, wet and dry swab, and HEPA vacuum sock samples on nonporous surfaces indicated good agreement between results with HEPA vacuum and wipe samples. However, results from HEPA vacuum sock and wipe samples agreed poorly with the swab samples. Dry swabs failed to detect spores >75% of the time when they were detected by wipe and HEPA vacuum samples. Wipe samples collected after HEPA vacuum samples and HEPA vacuum samples collected after wipe samples indicated that neither method completely removed spores from the sampled surfaces.
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Affiliation(s)
- Wayne T Sanderson
- Centers for Desease Control and Prevention , Atlanta, Georgia 30333, USA.
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25
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Abstract
Two versions of an electrically powered device (Rotorinser) to sample carcasses or other surfaces in situ for microbiological analysis and several different sampling protocols were evaluated against excision plus stomaching for ability to remove bacteria from pig skin and beef carcass tissue. Both devices sampled circular areas of approximately 14 cm2. Ten tissue samples were used for each set of conditions. Rotorinser bacterial removal efficiency was calculated as R/(R + S), where R is the Rotorinser count (CFU cm-2) and S is the count on stomached excised tissue after rotorinsing. Stomacher efficiencies were calculated as S1/(S1 + S2), where S1 is the first stomacher count of excised tissue and S2 is the count from a second stomaching. Both Rotorinsers were much better than traditional swabs. Rotorinser 1 gave removal efficiencies of 0.79 to 0.88 for beef, and 0.79 to 0.95 for pork. Prewetting surfaces for 5 min improved removal, but mixtures of enzymes did not. Rotorinser 2 applied with NaCl or NaCl-Tween 80 diluent for either 30 or 60 s was significantly better (0.93 and 0.98) than the stomacher (0.86) at removing aerobic mesophilic bacteria from pork skin. The Rotorinser causes negligible tissue damage and can be used on surfaces at any angle.
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Affiliation(s)
- A N Sharpe
- Bureau of Microbial Hazards, Food Directorate, Health Protection Branch, Health Canada, Tunney's Pasture, Ottawa, Ontario K1A 0L2
| | - C Isigidi Bin Kingombe
- Department of Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario K1H 8M5
| | - P Watney
- Biochemistry/Microbiology Cooperative Education Program, University of Victoria, British Columbia V8W 3P6, Canada
| | - L J Parrington
- Bureau of Microbial Hazards, Food Directorate, Health Protection Branch, Health Canada, Tunney's Pasture, Ottawa, Ontario K1A 0L2
| | - I Dudas
- Bureau of Microbial Hazards, Food Directorate, Health Protection Branch, Health Canada, Tunney's Pasture, Ottawa, Ontario K1A 0L2
| | - M P Diotte
- Bureau of Microbial Hazards, Food Directorate, Health Protection Branch, Health Canada, Tunney's Pasture, Ottawa, Ontario K1A 0L2
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