AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Characterization of Gelatin Filters for Sampling Bacillus Anthracis
KRISTIN BOWER, John Yeager, Paul Dabisch, NBACC
Abstract Number: 103 Working Group: Bioaerosols
Abstract There are many types of samplers that can be used to estimate the concentration of viable microorganisms present in an aerosol. Within the sampling process, there are many possible sources of loss, both physical and biological. Characterization of such losses is an important since losses which are unaccounted for will lead to an underestimation of dose in animal inhalation studies. In this study, the use of a gelatin filter to sample aerosolized Bacillus anthracis – both spores and vegetative cells – was characterized. Losses in viability associated with impaction velocity onto the filter medium and retention of collected microorganisms in a viable state for the duration of sampling were assessed. To this end, preparations of B. anthracis spores and vegetative B. anthracis were aerosolized into a small test system and sampled with 25-mm gelatin filters. The filters were operated at flow rates ranging from 0.25 L/min to 1.0 L/min to vary impaction velocity at the filter face. For a subset of samplers, additional clean air was pulled through the filter post-collection to examine the effect of airflow on the viability of collected bacteria. Gelatin filters were dissolved and bacterial concentrations were determined by enumeration on trypticase soy agar plates. For both vegetative and spore preparations of B. anthracis, no significant difference in the measured aerosol concentration was observed among the different flow rates, suggesting that the filter face velocity does not affect the viability of the collected bacteria in the range of flows examined. Similarly, no significant change in the measured aerosol concentration was observed following additional airflow across the filter for either preparation, suggesting that desiccation of the collected bacteria does not occur during the durations tested. These results suggest that gelatin filters can be used for efficient sampling of both vegetative and spore preparations of B. anthracis.