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Nelson S, Hofacre K, Shah S, Silvestri E, Gallardo V, Mikelonis A, James R, Calfee MW. Evaluation of sample processing methods to improve the detection of Bacillus anthracis in difficult sample matrices. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 194:789. [PMID: 36104633 PMCID: PMC10410253 DOI: 10.1007/s10661-022-10467-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 09/10/2022] [Indexed: 06/15/2023]
Abstract
Large area sampling approaches have been developed and implemented by the US Environmental Protection Agency (EPA) to increase sample sizes, and potentially representativeness, in outdoor urban environments (e.g., concrete, asphalt, grass/landscaping). These sampling approaches could be implemented in response to an outdoor biological contamination incident or bioterrorism attack to determine the extent of contamination and for clearance following remediation. However, sample collection over large areas often contains an extensive amount of co-collected debris and native background microorganisms that interfere with the detection of biological threat agents. Sample processing methods that utilize basic laboratory equipment amenable to field deployment were selected and applied to turbid aqueous samples (TAS) to reduce particulates and native environmental organisms prior to culture and rapid viability-polymerase chain reaction (RV-PCR) analytical methods. Bacillus anthracis Sterne (BaS) spores were spiked into TAS collected by soil grab, wet vacuum collection from an outdoor concrete surface, or storm water runoff from an urban parking lot. The implementation of a sample processing method improved the sensitivity of culture and RV-PCR analytical methods for BaS spore detection in soil and wet vacuum TAS samples compared to baseline (minimal to no field processing methods applied). For soil, when the processing method was applied, samples with 15 colony forming units (CFU)/ml (60 CFU/g) and 1.5 CFU/mL (6 CFU/g) BaS spore load were detected using culture and RV-PCR, respectively. Most notably, the processing methods greatly improved the sensitivity of the RV-PCR analytical method for the wet vacuum TAS from no detection at the 1500 CFU/mL BaS spore load level to as low as 1.5 CFU/mL BaS spore load.
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Affiliation(s)
- Scott Nelson
- Battelle Memorial Institute, King Avenue, Columbus, OH, USA
| | - Kent Hofacre
- Battelle Memorial Institute, King Avenue, Columbus, OH, USA
| | - Sanjiv Shah
- U.S. Environmental Protection Agency, Pennsylvania Avenue, Washington, DC, USA
| | - Erin Silvestri
- U.S. Environmental Protection Agency, Martin Luther King Drive, Cincinnati, OH, USA
| | - Vicente Gallardo
- U.S. Environmental Protection Agency, Martin Luther King Drive, Cincinnati, OH, USA
| | - Anne Mikelonis
- U.S. Environmental Protection Agency, 109 TW Alexander Drive, Durham, NC, 27711, USA
| | - Ryan James
- Battelle Memorial Institute, King Avenue, Columbus, OH, USA
| | - M Worth Calfee
- U.S. Environmental Protection Agency, 109 TW Alexander Drive, Durham, NC, 27711, USA.
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Wood J, Touati A, Abdel-Hady A, Aslett D, Delafield F, Calfee W, Silvestri E, Serre S, Mickelsen L, Tomlinson C, Mikelonis A. Decontamination of soil contaminated at the surface with Bacillus anthracis spores using dry thermal treatment. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2021; 280:111684. [PMID: 33303252 PMCID: PMC7899236 DOI: 10.1016/j.jenvman.2020.111684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 06/12/2023]
Abstract
In the event of a large, aerosol release of Bacillus anthracis spores in a major metropolitan area, soils and other outdoor materials may become contaminated with the biological agent. A study was conducted to assess the in-situ remediation of soil using a dry thermal treatment approach to inactivate a B. anthracis spore surrogate inoculated into soil samples. The study was conducted in two phases, using loam, clay and sand-based soils, as well as biological indicators and spore-inoculated stainless-steel coupons. Initial experiments were performed in an environmental test chamber with temperatures controlled between 80 and 110 °C, with and without added humidity, and with contact times ranging from 4 h to 7 weeks. Tests were then scaled up to assess the thermal inactivation of spores in small soil columns, in which a heating plate set to 141 °C was applied to the soil surface. These column tests were conducted to assess time requirements to inactivate spores as a function of soil depth and soil type. Results from the initial phase of testing showed that increasing the temperature and relative humidity reduced the time requirements to achieve samples in which no surrogate spores were detected. For the test at 80 °C with no added humidity, 49 days were required to achieve soil samples with no spores detected in clay and loam. At 110 °C, 24 h were required to achieve samples in which no spores were detected. In the column tests, no spores were detected at the 2.5 cm depth at four days and at the 5.1 cm depth at 21 days, for two of the three soils. The experiments described in the study demonstrate the feasibility of using dry thermal techniques to decontaminate soils that have been surficially contaminated with B. anthracis spores.
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Affiliation(s)
- Joseph Wood
- United States Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
| | | | | | - Denise Aslett
- Jacobs Technology, Inc, Research Triangle Park, NC, USA
| | | | - Worth Calfee
- United States Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA
| | - Erin Silvestri
- United States Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA
| | - Shannon Serre
- United States Environmental Protection Agency, Office of Emergency Management, Research Triangle Park, NC, USA
| | - Leroy Mickelsen
- United States Environmental Protection Agency, Office of Emergency Management, Research Triangle Park, NC, USA
| | - Christine Tomlinson
- United States Environmental Protection Agency, Office of Emergency Management, Washington, D.C., USA
| | - Anne Mikelonis
- United States Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA
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