The survival of Listeria monocytogenes in aerosols

Abstract

Aerosols of Listeria monocytogenes were generated in 0.1 % reconstituted nonfat dried milk, 0.1% peptone water, and distilled water. Suspensions of L. monocytogenes Scott A and L. monocytogenes V37CE were prepared in three population ranges: high, between 108-109 CFU/ml; intermediate, between 105-106 CFU/ml; and low, between 103-104 CFU/ml. Aerosols were generated into an enclosed hood by pressurized Freon. Prepoured petri plates containing tryptic soy agar with 0.6% yeast extract (Difco, Detroit, MI) were spread out in the bottom of the hood. Fallout was collected by removing the lids of randomly selected plates and leaving the lids off for selected time periods. The time periods used for collecting fallout varied and were based on the initial populations of the solutions that were aerolized. Fallout was reported as CFU/cm2 at each time interval. Results showed that high populations of L. monocytogenes Scott A and L. monocytogenes V37CE survived in aerosol suspensions generated under these conditions for 210 min.