Previous studies have demonstrated that aerosol sampling devices can have deleterious effects on bacteria due to stresses intrinsic to the sampling processes. Although a significant amount of work has been carried out to develop animal models of inhalational melioidosis, little information has been reported on the effects of the aerosol sampling devices on the causative bacterium, Burkholderia pseudomallei. The aim of this study was to compare the efficiencies for collection of aerosolized bacteria in three sampling devices that have been used in studies utilizing aerosolized B. pseudomallei. The data from this study demonstrate the equivalence of the Mercer impactor, gelatin filter, and model 7541 AGI for sampling respirable aerosols containing B. pseudomallei across a range of aerosol concentrations. It was also determined that the retention efficiency of gelatin filters for culturable B. pseudomallei was near unity, suggesting that desiccation of collected material did not occur for the short sampling period tested. The retention efficiency of the model 7541 AGI for culturable B. pseudomallei was significantly less than unity, and it was determined that this decrease was likely due to the stresses associated with repetitive sampler bubbling. The results of this study also confirmed the results of previous studies on the deleterious effects of the Collison nebulizer on microorganisms and extended these data to include B. pseudomallei.

A well-characterized exposure chamber is necessary to generate reproducible atmospheres for inhalation toxicology studies. The aim of the present study was to characterize a head-only exposure chamber for non-human primates. Aerosols containing bovine serum albumin (BSA) were used to characterize a 16-L dynamic airflow head-only exposure chamber. A 250-ml plastic bottle with a respirator attached located inside the chamber was used to simulate a breathing head. Chamber leak rate, mixing, and aerosol spatial distributions were quantified. The chamber concentration profile was measured at the chamber exhaust using an aerodynamic particle sizer. Aerosol spatial distribution was determined by collecting filter samples at several chamber locations. The particle size distribution was determined by collecting cascade impactor samples at several chamber locations. The estimated chamber leak rate was within standards suggested in the literature. The measured average aerosol residence time was similar to theoretical aerosol residence time, suggesting that the chamber was mixing well. Additionally, the average concentration measured at each of the sampling locations within the chamber was similar, and the within-run coefficients of variation (CV) across all sampling locations was similar to those reported in previously published studies, again suggesting that the aerosol concentration throughout the chamber was uniform. The particle size distribution was similar throughout the exposure chamber. Additionally, the BSA concentration and particle size distributions measured in the breathing zone of the simulated head were not significantly different from measurements made elsewhere in the chamber, suggesting that respiration does not affect the average aerosol concentration or particle size distribution at the mouth.