Human enteric pathogen internalization by root uptake into food crops.

With an increasing number of outbreaks and illnesses associated with produce contaminated before harvest, understanding the potential and mechanisms of produce contamination by enteric pathogens can aid in the development of preventative and post-harvest processing measures to reduce microbial populations. Enteric pathogens localized at subsurface sites on leafy green plant tissue prevent their removal during washing and inactivation by sanitizers. Root uptake of enteric pathogens and subsequent internalization has been a large area of research with results varying due to differences in experimental design, systems tested, and pathogens and crops used. The potential for uptake of foodborne pathogen, both bacterial and viral, through roots into food crops is reviewed. Various factors shown to affect the ability of human pathogens to internalize include growth substrate (soil vs. hydroponic solution), plant developmental stage, pathogen genus and/or strain, inoculum level, and plant species and cultivar. Several mechanisms of internalization ("active" vs. "passive") of bacteria to plant roots have also been hypothesized.