Development of an Aerosol System for Uniformly Depositing Bacillus Anthracis Spore Particles on Surfaces

Baron, Paul A.; Estill, Cheryl Fairfield; Deye, Gregory J.; Hein, Misty J.; Beard, Jeremy K.; Larsen, Lloyd D.; Dahlstrom, Gregory E.

doi:10.1080/02786820801918605

Cited by 16 publications

(30 citation statements)

References 21 publications

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“…Brown et al (4)(5)(6) tested various methods of collecting samples of Bacillus subtilis spores on porous and nonporous surfaces using this approach. In these studies, surface spore concentrations of 10 2 to 10 5 CFU/cm 2 were achieved. More recently, Baron et al (2) developed a system to deposit Bacillus anthracis and Bacillus globigii spores on agar plates, achieving concentrations of up to 200 CFU per plate using a particle settling chamber.…”

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confidence: 93%

“…In these studies, surface spore concentrations of 10 2 to 10 5 CFU/cm 2 were achieved. More recently, Baron et al (2) developed a system to deposit Bacillus anthracis and Bacillus globigii spores on agar plates, achieving concentrations of up to 200 CFU per plate using a particle settling chamber. This system was designed to produce low and predictable surface loadings for spore detection research.…”

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confidence: 93%

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Development of an Aerosol Surface Inoculation Method for Bacillus Spores

Ryan

Snyder

2011

Appl Environ Microbiol

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A method was developed to deposit Bacillus subtilis spores via aerosolization onto various surface materials for biological agent decontamination and detection studies. This new method uses an apparatus coupled with a metered dose inhaler to reproducibly deposit spores onto various surfaces. A metered dose inhaler was loaded with Bacillus subtilis spores, a surrogate for Bacillus anthracis. Five different material surfaces (aluminum, galvanized steel, wood, carpet, and painted wallboard paper) were tested using this spore deposition method. This aerosolization method deposited spores at a concentration of more than 10 7 CFU per coupon (18-mm diameter) with less than a 50% coefficient of variation, showing that the aerosolization method developed in this study can deposit reproducible numbers of spores onto various surface coupons. Scanning electron microscopy was used to probe the spore deposition patterns on test coupons. The deposition patterns observed following aerosol impaction were compared to those of liquid inoculation. A physical difference in the spore deposition patterns was observed to result from the two different methods. The spore deposition method developed in this study will help prepare spore coupons via aerosolization fast and reproducibly for bench top decontamination and detection studies.In response to the 2001 Bacillus anthracis spore incidents in the United States, many studies have investigated various technologies to sample media, detect biological agents, and decontaminate materials (3,9,10,(17)(18)(19)21). These laboratory studies typically use small coupons and laboratory inoculants to simulate the materials and biological agents that occur in field events. In these studies, test coupons should have reproducible numbers of viable spores on varied surface types. In addition, it is critical that the coupons are prepared so that the inoculation is representative of contamination as it occurs in the field. Liquid inoculation protocols that use suspended spores in aqueous buffers have been the primary methods used to prepare test surfaces for biological agent decontamination and detection studies (15,16,20). Liquid inoculation methods offer advantages in that they allow relatively easy control of the number of spores and the contaminated area. However, it is unclear whether surfaces contaminated by liquid inoculation methods are representative of surfaces contaminated with aerosolized Bacillus anthracis spores. Therefore, it is necessary to investigate the impact of various spore deposition methods on Bacillus anthracis decontamination and detection studies.The conventional particle deposition method via aerosolization is comprised of an aerosol generating system, such as a particle nebulizer, to introduce the spores into a chamber and a second chamber to allow the spores to settle onto the target material surfaces. The spore surface concentrations are controlled by varying settling time and the initial aerosolized spore concentration in the chamber. tested various methods of collecting ...

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confidence: 93%

Development of an Aerosol Surface Inoculation Method for Bacillus Spores

Ryan

Snyder

2011

Appl Environ Microbiol

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“…They found with the low number of chamber runs and the high variability, the confidence intervals were very wide. Additionally, re-aerosolization of spores during these samples was an issue, especially at the lower levels (Baron et al, 2008). Lewandowski et al (2010) evaluated Bacillus atrophaeus to determine the recovery efficiencies from glass and stainless steel surfaces using polyester swab and macrofoam sponge wipe.…”

Section: Wipe Samplingmentioning

confidence: 99%

“…One chamber used to deposit bioaerosols was designed and build by the Centers for Disease Control (CDC) and Dugway Proving Ground and designed to uniformly deposit spore particles on surfaces (Baron et al, 2008). Used for several different experiments (Baron et al, 2007;Baron et al, 2008;Estill et al,.…”

Section: Aerosol Test Chambersmentioning

confidence: 99%

“…The spores were found to be uniform in size and appearance and the aggregates which were larger had a propensity to pulverize; therefore, the particles dispersed into smaller particles (Parker, 2001). Also, some of the material was believed to be in a form that had silica added, or a fluidized form (Baron et al, 2008), which was a powdered suspension easily dispersed into the air (Parker, 2001). Overall, this showed that some individuals were exposed to aerosols generated from residual spore material on contaminated surfaces and demonstrated that spores can be reaerosolized from surfaces during office activities (such as paper handling, foot traffic, moving containers, etc) even after a period of no entry and no ventilation for several days (Weis et al, 2002).…”

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Decontamination of Bioaerosols within Engineering Tolerances of Aircraft Materials

Frazey¹,

Reynolds²

2012

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DECONTAMINATION OF BIOAEROSOLS WITHIN ENGINEERING TOLERANCES OF AIRCRAFT MATERIALSBacillus anthracis spores are generally considered the most difficult biological agents to decontaminate or inactivate. Inactivation of these spores is further complicated on aircraft because engineering specifications do not allow for chemical disinfectants to be used. Aircraft, however, must meet strict engineering specifications, requiring extended storage at temperatures greater than 185° F at 100% relative humidity (RH). Heat and humidity near these levels have been tested to determine if they can inactivate spores; however, these studies have only evaluated spores in high concentrations (10 6 spores) on aluminum coupons. This dissertation research was designed to evaluate the effectiveness of high heat and humidity on Bacillus atrophaeus subsp globigii (BG) spores, a simulant commonly used for Bacillus anthracis, when delivered via three different methods onto two different materials.In Chapter 2, an innovative bioaerosol deposition chamber design and testing is described. The test chamber was designed to deposit Bacillus atrophaeus subsp globigii (BG) spores onto coupons modeling real aircraft components. Deposition equations were derived to model the spore deposition. Initial deposition tests with fluorescent particles were inconclusive because the limit of quantification could not be reached; therefore, the BG spores were used to test deposition. Initial tests demonstrated the parameters that could be manipulated throughout the experiments to control the spore deposition. After these were evaluated, four final tests were completed to perform more in-depth statistical analysis. The coefficients of variation for these tests were within acceptable ranges (all were 25.5% or less). Ryan-Joiner tests were performed iii on the data and showed that 2 of the 4 tests displayed a lognormal distribution, while the other 2 tests were inconclusive. All data was therefore treated as a lognormal distribution. Contour plots were then constructed to determine if a discernible pattern was present. While these contour plots showed a somewhat even dispersion, there were no discernible patterns.Additionally, the plots showed a wide range of spore deposition throughout the four tests.Finally, the equations derived for spore deposition were validated. The data showed that 8.67%up to 31.0% (average of 20.25%) of the spores modeled could actually deposit and be recovered through culture methods. These losses could have occurred during the nebulization through inactivation or clumping after the spores were aerosolized. Regardless, this showed that the equations could be used after accounting for these losses. The study demonstrated that the test chamber can be used for spore depositions with the caveat that future studies include an appropriate control coupon next to each sample.In Chapter 3, decontamination of aluminum coupons was evaluated using the BG spores inoculated in three different methods-high direct inoculation (10 6 spores per c...

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