Viable Approach for the Detection of Bacteriological Contamination in Particulate Food Commodities by Aerosol Sampling

PAMELA MUROWCHICK (1), David Alburty (1), Ann Packingham (1), Anthony Bashall (2), Kevin Humphrey (2)

(1) AlburtyLab, Inc., (2) Hollison Technologies, Inc.

     Abstract Number: 782
     Last modified: May 14, 2010

Abstract
Hollison Technologies has developed an air sampling and large particle knockout technology for use as a front end in a bacteriological contaminant detection system in transfer operations in the food commodities industry. They are currently developing a protocol for teaming this technology with the InnovaPrep OMNI aerosol-to-hydrosol sampler for providing liquid samples to an appropriate detection system and assay for detection of bacteria of interest.

Hollison desired to test the ability of the Evogen Evocycler Polymerase Chain Reaction system and associated assays to detect three common food pathogens Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes. The purpose of this test program was to provide Hollison Technology with the information necessary to determine if these systems are suitable for pairing with their technology. Aerosol testing with the bacteria was performed by AlburtyLab personnel at the BioSafety Level 2 laboratory located near Drexel, Missouri. The InnovaPrep OMNI air sampler and the reference methods were exposed to the bacteria, individually and in the presence of aerosolized corn grain dust. Corn grain dust was aerosolized using an acoustic aerosol generator and entrained in a flow tube and the three food pathogens were introduced individually with the grain dust by nebulization.

Initial setup and shakedown of the sampling system was performed to determine the parameters necessary for controlling the grain dust aerosolization intended to mimic aerosolization of corn grain dust during unloading operations. The design of the overall sampling system for safe co-aerosolization of dry background materials and viable pathogenic organisms is described. Sample preparation methods for analysis by PCR and viable assay, difficulties encountered and a comparison of the results, is included.

The work strongly suggests that a wide range of bacteriological contaminants present in particulate food such as grain, tea, coffee, nuts, pepper, rice, cereals, etc., could be collected, sampled and detected using this approach.