Evaluation of slit sampler in quantitative studies of bacterial aerosols

Impact of air humidity on the tenacity of different agents in bioaerosols

Despite the variety of pathogens that are transmitted via the airborne route, few data are available on factors that influence the tenacity of airborne pathogens. In order to better understand and thus control airborne infections, knowledge of these factors is important. In this study, three agents, S. aureus, G. stearothermophilus spores and the MS2 bacteriophage, were aerosolized at relative humidities (RH) varying between 30% and 70%. Air samples were then analyzed to determine the concentration of the agents. S. aureus was found to have significantly lower survival rate in the aerosol at RH above 60%. It showed the lowest recovery rates of the three agents, ranging from 0.13% at approximately 70% RH to 4.39% at 30% RH. G. stearothermophilus spores showed the highest tenacity with recovery rates ranging from 41.85% to 61.73% with little effect of RH. For the MS2 bacteriophage, a significantly lower tenacity in the aerosol was observed with a recovery rate of 4.24% for intermediate RH of approximately 50%. The results of this study confirm the significant influence of the RH on the tenacity of airborne microorganisms depending on the specific agent. These data show that the behavior of microorganism in bioaerosols is varies under different environmental conditions.

An adhesive surface sampling technique for airborne viruses

A mixture of sucrose, glycerol and bovine serum albumin produces a stable coating in a Petri dish which remains adhesive for up to an hour when exposed in a slit sampler. Virus aerosols can be collected on this surface followed by the direct addition of cell cultures to demonstrate the presence of viable virus. The technique is applicable to the Andersen sampler. A modified version of this sampler has been produced with the same particle collection efficiency as the standard Andersen sampler. The plaque counts obtained by the adhesive surface sampling technique are believed to give an indication of the number of particles collected bearing viable virus.