Keywords

Bacillus anthracis; Bacillus thuringiensis; microbial recovery; bioterrorism;

Location

Session H1: Environmental Modeling, Software, and Data to Support Quantitative Microbial Risk Assessments (QMRAs)

Start Date

16-6-2014 9:00 AM

End Date

16-6-2014 10:20 AM

Description

The ability of microorganisms to persist on fomite surfaces is an important component in modeling their spread in physical environment. For example, Bacillus anthracis (Ba) spores have been found to be extremely resistant to inactivation, environmental stresses, and stable over decades. Modeling the inactivation of spores could form an integral element for estimating the exposure and the subsequent health risks posed by them. However, there is a knowledge gap in the quantification of recovery of Bacillus spores on porous surfaces, which may have a significant effect on the quantification of their persistence in the environment. Our work investigates the recovery of spores of two Bacillus species from HVAC filters, an example of porous fomite media, which can capture a significant quantity of microorganisms when there is an attack of bioterrorism. These filters have been found to become distribution conduits in the entire building following a bioterror attack. From preliminary results of recovery over a 48 hour period, the trends of inactivation and recovery of Bacillus spores were examined using culture-based quantification. Bacillus thuringiensis (Bt) showed an increase in recovery over time however it had the lowest mean recovery in comparison to Ba. This work was expanded to understand the recovery of spores better over a 168 hour period. As seen in the preliminary studies, there was an increase followed by a decrease in Bt spores after a 24 hour period with an overall log10 reduction equivalent to 22.5% of the observed log reduction of Ba. A comparative analysis of recovery is presented in order to fill knowledge gaps surrounding the potential effect of recovery on models of microbial inactivation for organisms with long-term persistence. The future work of this research will utilize molecular-based quantification in order to differentiate between the live and dead counts among the recovered population.

 
Jun 16th, 9:00 AM Jun 16th, 10:20 AM

The Effect of Recovery on Modeling Inactivation of Bacillus Spores on HVAC Filters

Session H1: Environmental Modeling, Software, and Data to Support Quantitative Microbial Risk Assessments (QMRAs)

The ability of microorganisms to persist on fomite surfaces is an important component in modeling their spread in physical environment. For example, Bacillus anthracis (Ba) spores have been found to be extremely resistant to inactivation, environmental stresses, and stable over decades. Modeling the inactivation of spores could form an integral element for estimating the exposure and the subsequent health risks posed by them. However, there is a knowledge gap in the quantification of recovery of Bacillus spores on porous surfaces, which may have a significant effect on the quantification of their persistence in the environment. Our work investigates the recovery of spores of two Bacillus species from HVAC filters, an example of porous fomite media, which can capture a significant quantity of microorganisms when there is an attack of bioterrorism. These filters have been found to become distribution conduits in the entire building following a bioterror attack. From preliminary results of recovery over a 48 hour period, the trends of inactivation and recovery of Bacillus spores were examined using culture-based quantification. Bacillus thuringiensis (Bt) showed an increase in recovery over time however it had the lowest mean recovery in comparison to Ba. This work was expanded to understand the recovery of spores better over a 168 hour period. As seen in the preliminary studies, there was an increase followed by a decrease in Bt spores after a 24 hour period with an overall log10 reduction equivalent to 22.5% of the observed log reduction of Ba. A comparative analysis of recovery is presented in order to fill knowledge gaps surrounding the potential effect of recovery on models of microbial inactivation for organisms with long-term persistence. The future work of this research will utilize molecular-based quantification in order to differentiate between the live and dead counts among the recovered population.