Chapter 8 - Salmonella and tomatoes

Abstract

While salmonellosis is historically associated with animal products, a diverse array of fresh produce hase been identified as the cause of Salmonella enterica outbreaks over the past decades. Within this timeframe, tomatoes have been associated with dozens of outbreaks. Contamination sources, including irrigation water, soil amendments, and postharvest handling have been shown to contribute to an increased risk of contamination. Multiple factors contribute to the persistence and proliferation of Salmonella in and on tomato fruit. Evidence has shown that bacteria can internalize through natural apertures in tomato fruit during crop development and tomato wash systems as a result of cross-contamination. Salmonella spp. are characterized as having broad pH and temperature tolerances, with the ability to adapt in environments that are sub-optimal for growth. Once internalized, Salmonella is capable of sensing the availability of nutrients and physiological state of the fruit and differentially regulates specific genes. Furthermore, enteric pathogens, such Salmonella and pathogenic E. coli are not able to metabolize plant cell walls through pectic degradation; however, the presence and growth of soft rot bacteria provide a metabiotic relationship that favors enteric bacteria. The ability of Salmonella to adapt to its environment and utilize tomato plants as an alternative host underscores the importance of effective control measures such as good agricultural practices.