Q-175. Microbial Characterization of Bioaerosols in Concentrated Animal Feeding Operations

M. Rodríguez de Evgrafov, P. Köll, L. K. Baumgartner, M. T. Hernandez, D. N. Frank, N. R. Pace;
Univ. of Colorado, Boulder, CO.

Background: Concentrated animal feeding operations (CAFOs) involve high densities of animals (thousands/building) raised indoors to reduce labor costs and maintain uniform climate control. CAFO workers are exposed to large quantities of airborne microbes, antigens and toxins, which results in acute respiratory disease and potentially unrecognized chronic respiratory problems. Our knowledge of CAFO aerobiology is primarily based on inefficient collection methods and culture studies, which likely detect only a small fraction of the potential biodiversity present. In response to this knowledge gap, the goals of this study were: (i) to quantify and identify airborne microorganisms present in CAFOs using culture independent techniques; and (ii) to develop PCR based assays applicable for the detection and quantification of select potential pathogens. Methods: To achieve these objectives, direct microscopy, “universal” PCR (515F/1391R), and DNA sequence analyses were conducted on air samples collected from swine and cattle operations in the western placecountry-regionUnited States. Phylogenetic analyses were used to identify the composition of airborne communities. Results: We report here that indoor microbial loads were not elevated above their outdoor controls. Phylogenetic observations found that the indoor ecology was limited in diversity and dominated (>65%) by members of the Firmicutes, such as Bacillaceae, Clostridiaceae and Lachnospiraceae. We detected no respiratory pathogens of concern and opportunistic pathogens (relatives of Ruminococcus productus and Eubacterium rectale) only in low numbers. Additionally no fungal species were observed in any of the clone libraries. Conclusions: In contrast to previous studies, the contribution of fungal species to overall CAFO aerobiology is not as significant as once believed. Based on the phlyogenetic findings PCR assays are under development for select potential pathogenic members of the Firmicutes as well as for other pathogenic members from less observed phyla, such as Nocardia spp. and Mycobacterium spp.