Comparison of Air Sampling Methods for Aerosolized Spores ofB. anthracisSterne

Abstract

Bacillus anthracis Sterne spores were aerosolized within a chamber at concentrations ranging from 1 x 10³ to 1.7 x 10⁴ spores per cubic meter of air (particles (p)/m³) to compare three different sampling methods: Andersen samplers, gelatin filters, and polytetrafluoroethylene (PTFE) membrane filters. Three samples of each type were collected during each of 19 chamber runs. Chamber concentration was determined by an aerodynamic particle sizer (APS) for the size range of 1.114-1.596 μm. Runs were categorized (low, medium, and high) based on tertiles of the APS estimated air concentrations. Measured air concentrations and recovery efficiency [ratio of the measured (colony forming units (CFU)/m³) to the APS estimated (particles/m³) air concentrations] for the sampling methods were compared using mixed-effects regression models. Limits of detection for each method were estimated based on estimated recovery efficiencies. Mean APS estimated air concentrations were 1600 particles/m³, 4100 particles/m³, and 9100 particles/m³ at the low, medium, and high tertiles, respectively; coefficient of variation (CV) ranged from 25 to 40%. Statistically significant differences were not observed among the three sampling methods. At the high and medium tertiles, estimated correlations of measured air concentration (CFU/m³) among samples collected from the same run of the same type were high (0.73 to 0.93). Among samples collected from the same run but of different types, correlations were moderate to high (0.45 to 0.85); however, correlations were somewhat lower at the low tertile (-0.31 to 0.75). Estimated mean recovery efficiencies ranged from 0.22 to 0.25 CFU/particle with total CVs of approximately 84 to 97%. Estimated detection limits ranged from 35 to 39 particles/m³. These results will enable investigators to conduct environmental sampling, quantify contamination levels, and conduct risk assessments of B. anthracis.

Evaluation of applicability of the Sartorius Airport MD8 sampler for detection of Bacillus endospores in indoor air

“…Recently, Estill et al (2011) have described the aerosolization of B. anthracis Sterne endospores at relatively low concentrations (from 1 × 10 3 to 1.7 × 10 4 endospores/m 3 ) in a chamber filled with the HEPA-filtered air. One of the concentrations used for the aerosol generation was 9.1 × 10 3 particles/m 3 (as measured using APS), which corresponded to 2.28 × 10 3  CFU/m 3 (based on the estimation of 0.22−0.25 CFU/particle).…”

Comparative Testing and Evaluation of Nine Different Air Samplers: End-to-End Sampling Efficiencies as Specific Performance Measurements for Bioaerosol Applications

“…Compared to the BioSampler, the available performance data for the rest of the involved air samplers were more limited; gelatin filters (Li 1999;Lin and Li 1999;Tseng and Li 2005;Burton et al 2007;Fabian et al 2009;Van Droogenbroeck et al 2009;Chang and Chou 2011;Estill et al 2011;Zhao et al 2011), Coriolis FR (or Coriolis μ and δ) (Carvalho et al 2008;Gómez-Domenech et al 2010;Ahmed et al 2013), XMX-CV (or XMX/2L-MIL and XMX/2A) (Cooper 2010;Black 2011;Kesavan et al 2011;Black and Cooper 2012;Enderby 2012), BioCapture 650 (Kesavan et al 2011;Enderby 2012), OMNI-3000 (Kesavan et al 2011;Zhao et al 2011), SASS 2300(or SASS 2000 (Kesavan and Stuebing 2009;Kesavan et al 2011), andSASS 3100 (Kesavan et al 2010b).…”

Updating aB. anthracisRisk Model with Field Data from a Bioterrorism Incident

“…Prior distributions for model inputs were determined on the basis of a review of the literature. , − ,, A truncated normal (log-normal) distribution was selected for parameters, and their ranges are listed in Table . These prior distributions were updated by incorporating information extracted from observations reported by Weis et al using a Bayesian approach as described below. ,,, Fixed model inputs are listed in Table .…”