BACTERICIDAL EFFECTS OF NEGATIVE AIR IONS ON AIRBORNE AND SURFACE SALMONELLA ENTERITIDIS FROM AN ARTIFICIALLY GENERATED AEROSOL

Authors: Seo, Kun Ho; Mitchell, Bailey; Holt, Peter; Gast, Richard

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2000
Publication Date: 2/1/2001
Citation: Seo, K., Mitchell, B.W., Holt, P.S., Gast, R.K. 2001. Bactericidal effects of negative air ions on airborne and surface salmonella enteritidis from an artificially generated aerosol. Journal of Food Protection.

Interpretive Summary: To investigate whether ion-enriched air exerts a bactericidal effect, an aerosol containing Salmonella Enteritidis (SE) was pumped into a sealed plastic chamber. Plates of agar were attached to the walls, ceiling, and floor of the chamber and exposed to the aerosol for 3 hours with and without the ionizer treatment. The plates were then removed from the chamber, incubated at 37C for 24 hours, and colonies were counted. Greater than 1,000 cells/plate were observed on plates exposed to the aerosol without the ionizer treatment (control) compared with less than 20 cells/plate on the ionizer-treated plates. In another series of experiments, the SE aerosol was pumped for 3 h into an empty chamber containing only the ionizer and allowed to collect on the internal surfaces. The inside surfaces of the chamber were then rinsed with 100 ml saline solution which was then plated onto agar media. While the rinse from mthe control chamber contained colony counts greater than 400 cells/ml of wash, no colonies were found in the rinse from ionizer-treatment chamber. These results indicate that high levels of negative air ions can have a significant impact on the airborne microbial load and that most of this effect is through direct killing of the organisms. This technology, which also causes significant reduction in airborne dust, has already been successfully applied in poultry hatching cabinets and caged layer rooms.

Technical Abstract: Studies have demonstrated that transmission of Salmonella Enteritidis (SE) within a flock could occur via the airborne route, especially in stressed birds. To investigate whether the ionizer exerted a bactericidal effect on the organisms, a sealed plastic chamber was constructed into which an aerosol containing SE was pumped. On the walls, ceiling, and floor of the chamber were attached XLT4 plates which were exposed to the aerosol for 3 hours, in the presence or absence of the ionizer. The plates were removed from the chamber, incubated at 37C for 24 hours, and then counts were made. Greater than 1000 CFU/plate were observed on plates exposed to the aerosol without the ionizer compared with less than 20 CFU/plate on the ionizer exposed plates. Experiments where, after being exposed to the 3 hour aerosol, the inside surfaces of the chamber were rinsed with 100 ml PBS and the rinse plated onto XLT4 plates, showed that, while the rinse from the chamber exposed to the aerosol in the absence of the ionizer contained colony counts greater than 400 CFU/ml of wash, no colonies were found in the rinse from ionizer-exposed chambers. These results indicate that negative air ionization can have a significant impact on the airborne microbial load in a poultry house and at least a portion of this effect is through direct killing of the organisms.