Organic Control of STEC

Organic farming methods are touted as a heathy and sustainable alternative to conventional farming. However, organic methods use animal manures as fertilizer, leading to concerns of produce contamination. Preharvest contamination of leafy greens with enteric pathogens is a major concern, especially from shiga toxin producing Escherichia coli which can cause severe health issues and death. Survival of these pathogens was monitored on lettuce seedlings grown either organic or conventional soil. These experiments indicated that these pathogens survive poorly on organic grown lettuce compared to conventional grown lettuce and that this effect was more pronounced late in soil sampled late in the growing season. DNA sequence of both soils indicated the presence of several bacteria that are closely related to the pathogen, indicating that competition may play a role in the lower levels of the pathogen on organic grown lettuce.