AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Development and Implementation of Techniques to Investigate the Physiological Response of Bacteria to Aerosolisation
RICHARD THOMAS, Janine Jordan, David Cleary, Dstl
Abstract Number: 695 Working Group: Health Related Aerosols
Abstract Bacteria can be aerosolised into the atmosphere due to a number of activities such as man-made and natural (e.g. coughing, sneezing, showering, flushing toilets, emissions from cooling towers, farming, household dusting and spraying agricultural insecticides). For most bacteria this causes few problems for man; however, some bacteria can be transmitted in aerosols to cause disease. Yersinia pestis, the causative agent of plague, is one such pathogen, and this has serious implications in the event of an outbreak. The mechanisms behind the physiological response to aerosolisation are uncharacterised. The focus of this research is to develop a suite of techniques to enable a better understanding of this phenomenon for Y. pestis.
Particle size has been demonstrated to influence bacterial survival in organisms such as Pseudomonas syringae (Lighthart & Shaffer, 1997). Two different aerosol generation devices (Collison nebuliser and flow-focussing aerosol generator) were used to generate 1 and 12-micrometer particle aerosols of Y. pestis that were captured onto microthreads. These captured aerosol particles were assessed over time for viability at 50% relative humidity and ambient temperature.
Techniques for enumeration of Y. pestis cells sampled from aerosols have been developed based on PCR to determine the total number of captured cells and those with compromised membrane integrity, alongside conventional assessment of viability by colony formation.
The data indicated that over a short period of 15 min, the viability of Y. pestis measured by the formation of colonies on plating media was maintained in both 1 and 12-micrometer aerosol particles. However, after 30 min there was a significant reduction in viability within 1-micrometer particles that was not observed in the larger particles. The reduction in viability was not linked to loss of membrane integrity as irrespective of particle size, a significant reduction in membrane integrity was observed by 5 min.