10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Preliminary Evaluation of Commercial Bioaerosol Sampling Equipment in the Collection of Viable Aerosols of Clostridium difficile
CASEY COOPER, Kathleen Aithinne, David L. Johnson, University of Oklahoma
Abstract Number: 532 Working Group: Infectious Bioaerosol
Abstract Airborne disseminations of Clostridium difficile (C. difficile) spores in healthcare environments have been documented in multiple studies and are potentially linked to the high transmissibility of healthcare acquired C. difficile infections. Effective air sampling methodologies are necessary to properly assess risks posed by C. difficile generation in healthcare facilities, but to date no studies have been performed to compare the efficiencies of commonly used bioaerosol sampling methods in collecting C. difficile spore aerosols. This laboratory study compared slit-to-agar impactor, liquid impinger, and filtration methods in the collection of laboratory-generated C. difficile spore aerosol.
Four air samplers evaluated in this study were the Airtrace slit-to-agar impactor, AGI-30 impinger, SKC BioSampler impinger, and a 47 mm MCE filter. Non-toxigenic C. difficile spores (ATCC 700057) were nebulized into a well-mixed polypropylene plastic enclosure operating under negative pressure and contained within a Class 2 biological safety cabinet. Side-by-side air samples were drawn from the chamber into the samplers in combinations of the Airtrace and the two phosphate buffered saline-filled impingers or the Airtrace and two 47 mm filter cassettes. A filter cassette was placed in line with each impinger to assess potential re-aerosolization. The Airtrace, previously used in published studies to collect airborne C. difficile spores, served as the reference method against which the other methods were compared.
Relative collection efficiencies of the two impingers were similar and were low compared to the slit-to-agar impactor. Filter cassette efficiency was higher than the slit-to-agar impactor. Impinger re-aerosolization of collected spores was low and somewhat higher in the AGI-30 than in the BioSampler, consistent with previous published studies using polystyrene latex spheres of a similar size.
This study is the first to compare the relative sampling efficiencies of four commonly used bioaerosol sampling methods when measuring C. difficile spore aerosol. The results demonstrate that the impinger bioaerosol samplers with phosphate buffered saline media were not effective in the viable collection of C. difficile spore aerosol, compared to either the slit-to-agar impactor or MCE filters. Additional research is needed to evaluate alternative and additional bioaerosol sampling methods for the collection of this important pathogen.