Optimizing the Recovery of Surrogates for Bacterial Bioterrorism Agents from Ventilation Filters

Abstract

Heating, ventilating, and air-conditioning (HVAC) filters have the potential to serve as long-term integrated samplers for biological particles that may be released intentionally or unintentionally into a public building. Methods for eluting bacteria that are surrogates for potential bioterrorism agents from HVAC filters were tested for their ability to recover as high a percentage of culturable bacteria as possible. A solution of 0.02% Tween-80 in water was an effective eluent for Bacillus globigii (BG) spores whereas phosphate-buffered saline was the most effective eluent for vegetative bacteria. Hand shaking was a more effective agitation method for high recovery rates than vortexing or mechanical shaking. The results indicate that BG spores can be eluted successfully while maintaining essentially 100% culturability. The recovery of the vegetative bacteria Mannheimia haemolytica and Yersinia ruckeri was 80% or higher under optimal conditions. The culturability of the vegetative bacteria eluted from HVAC filters declined substantially within as little as 2 h after the bacteria were loaded onto the filter. The culturability of the BG spores eluted from filters exhibited an exponential decay subsequent to loading with a half-life of 8 -9 days.

Recovery balance: a method for estimating losses in a Bacillus anthracis spore sampling protocol

“…Improved recovery due to the addition of Tween 80 in wetting agent and extraction solutions has been associated with high environmental sampling performance (Kim et al . ; Da Silva et al . ).…”

“…All wetting agents utilized in this work containing Tween 80 (T80 and PBST) resulted in the best recovery efficiency (RE soln ) when compared with the other wetting agents by rank analysis (Table 2). Improved recovery due to the addition of Tween 80 in wetting agent and extraction solutions has been associated with high environmental sampling performance (Kim et al 2008;Da Silva et al 2011). In the current study, spores were likely entrapped in the wipe fibres contributing to the low release of spores from the wipes.…”

Evaluation of the Performance of Iodine-Treated Biocidal Filters Under the Influence of Environmental Parameters

“…Edwards et al (2004) showed similar extraction efficiencies of MS2 from FFR coupons by vortexing and by shaking. Kim et al (2008) showed that shaking gave twice higher efficiency than vortexing BG spores into ATCC medium (organic matter). The suggestion from these limited examples is that the efficiency may be both species and medium dependent.…”

Topical Issue: Bioaerosol Research

“…The first one (Kim, Raynor, Kuehn, Goyal, Ramakrishnan, Anantharaman, and Farnsworth of the University of Minnesota, USA) considers heating, ventilating, and air-conditioning (HVAC) filters as long-term integrated samplers of biological particles, which may be released intentionally or unintentionally into a public building [12]. While bacterial spores were shown to much more likely maintain their culturability than vegetative bacterial cells during filtration on HVAC filters, the authors demonstrated that the vegetative cells could be successfully eluted from HVAC filters even if they do not maintain their culturability.…”