Views on the survival, persistence and interaction of human pathogens with plants are now changing. Through various lines of research it is established that human pathogens can persist over extended periods in the environment especially when associated with plants. The extent to which human pathogens can internalize into undamaged plant tissue still remains to be elucidated. From studies performed to date it appears that human pathogens can internalize to a greater extent into sprouted seeds compared to mature plants. However, the fact that a diverse range of opportunistic human pathogens are frequently present in the endophytic microflora would imply that internalization of bacteria such as E. coli O157 is possible. Although it appears that many human pathogens that internalize into vegetables have low virulence, these should be considered a risk until proven otherwise. This has significant implications for safety strategies, as once internalized any pathogens present cannot be removed by simple washing. In this respect the only effective control method would be to prevent contamination of vegetables at each point of the chain (farm to fork). In the field environment the irrigation water quality and manure management have to be closely monitored. This is especially relevant in hydroponic cultivation systems where the interaction of human pathogens is greater compared to soil grown crops. In harvesting operations the transfer of enteric bacteria from infected workers has to be addressed. Although post-harvest processing of vegetables cannot ensure removal of pathogens, the sanitary standards of wash water have to be ensured. Importantly, food handlers need to minimize potential cross-contamination events during food preparation.
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