Aerosolization of Bacterial Spores with Pressurized Metered Dose Inhalers
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Bioaerosol detection and identification systems need to be periodically checked for assurance that they are responsive to aerosol challenges. Herein, pressurized metered dose inhalers (pMDIs) containing ethanol suspensions of two simulants for B. anthracis spores are considered for providing suitable aerosols. Doses and shot weights from pMDIs with canisters having volumes equal to that of 200 metering-valve actuations were constant for ≤165 actuations, but drop beyond that range. There were statistically significant dose variations between replicate pMDIs and between two types of actuators used on the pMDIs. The storage halflives of pMDIs filled with Bacillus atrophaeus (BG) and Bacillus thuringiensis subsp. israelensis (Bti) spore formulations are predicted to be 32 and 136 months, respectively, if the canisters are stored under refrigeration (4°C). The prediction is based on use of a logarithmic regression model relating CFU per actuation to storage time, with data taken at times of 1-12 months. Demonstration of the utility of the concept was provided by producing responses from a polymerase chain reaction (PCR) identifier with pMDI-generated BG and Bti aerosols that were collected with a 100 L/min wetted wall bioaerosol sampling cyclone. Copyright © American Association for Aerosol Research.
author list (cited authors)
Kesavan, J., Schepers, D. R., Bottiger, J. R., King, M. D., & McFarland, A. R.