Evaluation of vacuum filter sock surface sample collection method for Bacillus spores from porous and non-porous surfaces

Brown, Gary S.; Betty, Rita G.; Brockmann, J.E.; Lucero, Daniel A.; Souza, Caroline Ann; Walsh, Kathryn S.; Boucher, R. M. G.; Tezak, Matthew; Wilson, Mollye C.

doi:10.1039/b700163k

Cited by 48 publications

(63 citation statements)

References 13 publications

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“…The spore surface concentrations are controlled by varying settling time and the initial aerosolized spore concentration in the chamber. 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.…”

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confidence: 99%

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: 99%

Development of an Aerosol Surface Inoculation Method for Bacillus Spores

Ryan

Snyder

2011

Appl Environ Microbiol

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“…76 (Brown et al, 2007b ;Brown et al, 2007a Another aerosol generator is the flow-focusing aerosol generator (FFAG), which is used to generate particles larger than 10 μm. This instrument relies on the formation of a stable microjet which disintegrates at a defined distance from a critical orifice.…”

Section: Aerosol Generation Methodsmentioning

confidence: 99%

“…The tested deposition with aluminum oxide particles, monodisperse polystyrene spheres, and oleic acid droplets; however, they ultimately concluded that biological particle tests are needed due to the additional complications they add to the tests. Brown et al, aerosolized BG spores into a chamber and produced surface concentrations in the range of 10 2 to 10 5 colony forming units per square centimeter for the purposes of swipe sampling (Brown et al, 2007a(Brown et al, , 2007b(Brown et al, , 2007c. The chamber included a cylinder mixing chamber, constructed from carbon steel with enamel-coated surface, and a diameter of 45 cm, a height of 30 cm, and a total volume of 0.048 m 3 .…”

Section: Aerosol Test Chambersmentioning

confidence: 99%

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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“…Further, because of the variability produced by having to deal with live organisms, it is not likely that the accuracy in measurement for spores will meet the NIOSH criteria. In studies of spore recovery from surfaces, the variability of CFUs per sample is not usually reported, only the recovery efficiency and its variability (Rose et al 2004;Hodges et al 2006;Brown et al 2007a;2007b;2007c). Recovery efficiency values reported in the Brown et al studies had a range of 28-90%; .…”

Section: Introductionmentioning

confidence: 99%

“…The spores were allowed to settle onto flooring material placed on a bench. Brown et al (2007a;2007b;2007c) spores into a chamber and produced surface concentrations in the range of 10 2 to 10 5 colony forming units per cm 2 . In the anthrax attack of 2001, some of the material was believed to be in a "fluidized" form (defined here as having fumed silica added).…”

Section: Introductionmentioning

confidence: 99%

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

Baron

Estill

Deye

et al. 2008

Aerosol Science and Technology

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After the anthrax incidents in October 2001, several techniques used for sampling surfaces for biological agents were found to be inadequately validated, especially at low surface loadings. Therefore a test chamber was developed to produce sample sets having targeted surface concentrations of dry biological agent simulant. Dry spore aerosols were initially dispersed into the chamber at relatively high air concentrations, and monitored in real time. The concentration decay (due to stirred settling and dilution) was measured and when the targeted air concentration was reached, the sampling surfaces were uncovered and exposed to the settling particles until >99% of the particles had settled. Multiple agar plates were used to estimate the true colony-forming-unit (CFU) surface concentration. The uniformity of surface loadings was limited by random deposition of small numbers of particles on the surfaces (Poisson distribution) and was characterized by how much greater the observed variability was than that predicted by Poisson statistics. The flow-enhanced powder mixture appeared to affect the spores' ability to grow on the agar medium. Three ways of analyzing the agar plates were used to evaluate the effect of spore coatings on viability and to differentiate between number of spore-containing particles and the number of spores. The presence of spore agglomerates resuspended by various sample handling activities in the chamber further increased the variability of deposited particles. Based on estimated airborne particle concentration, it was possible to predict mean agar plate concentrations within narrow confidence intervals (CI) at low (4.8 CFU, 95% CI 3.5-6.4), medium (20 CFU, 95% CI 17-23), and high (160 CFU, 95% CI 140-190) concentrations.

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Evaluation of vacuum filter sock surface sample collection method for Bacillus spores from porous and non-porous surfaces

Cited by 48 publications

References 13 publications

Development of an Aerosol Surface Inoculation Method for Bacillus Spores

Development of an Aerosol Surface Inoculation Method for Bacillus Spores

Decontamination of Bioaerosols within Engineering Tolerances of Aircraft Materials

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

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