Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 10/8/2003
Publication Date: 11/6/2003
Citation: Fratamico, P.M., Annous, B.A. 2003. Detection of pathogens in fruits and vegetables. NFRI, Japan Meeting Abstract. Interpretive Summary:
Technical Abstract: During the past two decades, there has been an increase in human illnesses linked to the consumption of fresh produce, sprouts, and fruit juices contaminated with pathogens such as Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, Shigella spp., Cryptosporidium parvum, and hepatitis A. Studies on the sources, levels, and prevalence of different pathogens found in produce are needed to develop effective control strategies. To conduct these studies and to ensure a safe and wholesome food supply, sensitive, reliable, and specific assays for pathogen detection are needed. Detection technologies can be categorized into three groups: cultural-based or conventional methods; immunological or antibody-based assays; and genetic-based assays such as the polymerase chain reaction (PCR). The sensitivity and accuracy of food testing results are dependent on a number of factors including the type of food, the method of sample collection and preparation, the size and number of samples collected, and the selection of the appropriate enrichment media and detection method. A 'rapid method' can be described as a test that can provide results in a relatively short period of time. Rapid tests include miniaturized biochemical kits, antibody- or nucleic acid- based kits, and conventional methods that have been modified to provide results more quickly. Rapid methods have been used successfully for the isolation, identification, detection, and characterization of pathogens found in produce. Methodologies were developed to determine the presence of E. coli O157:H7 in a pasture and whether proximity of the pasture to an orchard correlates to the likelihood of finding the pathogen in the soil or on the fruit. E. coli O157:H7 was detected in the soil in the orchard and in fecal samples from cows in the pasture adjacent to the orchard. The PCR and pulsed-field gel electrophoresis results showed that the strains were indistinguishable. Results of this study showed that use of a combination of a cultural method for isolation, genetic and immunologic methods for confirmation, and typing methods to determine relatedness of isolates can provide valuable information on the presence and source of E. coli in the environment and in the food.