Detection of human pathogens on plants

Abstract

Unlike most plant pathogens, which typically multiply to large numbers after colonizing tissues of susceptible plants, human pathogens that associate with plants often fail to thrive in this environment and usually occur in low numbers. Nevertheless, their presence on plants could have significant public health and economic consequences. In recent years, national and international disease outbreaks associated with human pathogens on plant products, such as lettuce, spinach, green onions, seeds, sprouts, peppers, spices, tomatoes, and cantaloupes, have occurred frequently. Current standardized assays for the detection of major human pathogens on plants rely largely on microbiological, biochemical, and immunological analyses that are laborious and time consuming. Newer molecular-based methods, such as PCR, loop mediated isothermal amplification, and metagenomics approaches offer enhanced speed and sensitivity, and some of these have already been incorporated into the standard assays. However, molecular detection methods do not produce a live microbial isolate, which may be needed for government regulatory actions and future scientific studies. New enrichment strategies (especially the use of chromogenic selective media) have made culture detection more sensitive and accurate. Effective detection and diagnostic methods of the future will continue to differ in features depending upon the intended application and operators.