| The proportion of foodborne illnesses associated with fresh produce has increased over the last decade. In an effort to address this concern, the objectives of the first three studies were (i) to determine the quality and safety of produce sampled from the farm and packing sheds by enumerating microbial indicator organisms and testing for various pathogens; (ii) to examine the routes of microbial contamination in domestic and imported produce, and identify areas of potential contamination throughout production and processing; and (iii) to characterize the antimicrobial resistance profiles of Enterococcus spp. among fresh produce. The purpose of the final study was to develop a method to pre-concentrate pathogens from sprouts and spent irrigation water to facilitate the direct (without prior cultural enrichment) detection of pathogens using the polymerase chain reaction (PCR).; Results from the field studies showed that levels of microbial indicators, including total bacteria, coliforms, enterococci, and E. coli remained constant, and in some cases, increased during the processing phase. Extremely low levels of pathogens were found among both studies. In most cases, imported samples were found to be of higher microbial quality than domestic samples. The degree of environmental contamination from swabs was similar to that found for produce. Furthermore, Enterococcus spp. isolated from both studies revealed an overall low resistance to antibiotics of both animal and human relevance.; In the final study, alfalfa sprouts and spent irrigation water were seeded with Salmonella Typhimurium and Escherichia coli O15:H7 in the range of 10-1 to 106 CFU/g or ml and pre-concentrated by centrifugation. The resulting precipitate was then processed for DNA isolation, PCR amplification, and amplicon confirmation by Southern hybridization. Using primers targeting the inv A gene for serovar Typhimurium and the stx genes of E. coli O157:H7, it was possible to detect both pathogens in alfalfa sprouts at seeding levels as low as 101 CFU/g. PCR detection limits for both pathogens from spent irrigation water were 10-1 CFU/ml.; This research contributes to a body of knowledge that will assist in the design of effective intervention strategies for the lowering the risk of foodborne disease associated with fresh produce. |
