Longitudinal sampling of organic farms for microbiological quality farmers’ market produce: bacteria and antibiotic resistance on USDA certified organic farms that use biological soil amendments of animal origin

Authors: ZIMERI, ANNE-MARIE - UNIVERSITY OF GEORGIA; Oladeinde, Adelumola - Ade

Submitted to: National Environmental Health Forum
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The popularity of farmers’ markets has increased in recent years because of the desire of the public to consume foods grown locally and without the use of antibiotics or pesticides. USDA certified organic produce, dairy, beverages, packaged foods, grains, snacks, meat, fish, and poultry account for 4% of total food sales. These sales have surpassed $35 billion in recent years. Public perception of USDA organic foods includes the impression that these foods are free of all pesticides and microbes that are traditionally associated with conventionally grown produce. However, food-borne pathogen outbreaks associated with produce from organic production and those associated with meat from backyard poultry flocks has made it clear that more information is needed to determine the microbial population of products obtained from these farms and sold at farmers markets. To address this question, an initiative in 2016 began in Northeast Georgia to assess food safety in the organic marketplace. We conducted a longitudinal study to assess the microbiological quality of soil, water and produce samples taken from organic farms using biological soil amendments of animal origin (BSAAO) for growing squash for sale at local farmers markets. Squash was selected because it is an above ground crop with an edible portion that contacts the soil and it has two plantings and harvest in Northeast Georgia. Though food-borne pathogens were not detected in BSAAO, soil, water or squash, E. coli was detected sporadically. And, coliforms (Pantoea spp, Enterobacter spp, Raoultella spp and Serratia spp) and Enterococcus were present in high abundance on the interior and exterior of squash. We did find that squash cleaned prior to selling at farmer’s market had lower abundance of bacteria. Antibiotic resistance, which can be horizontally transferred, was tested in coliforms and Enterococcus. ß-lactam resistance was the major resistance carried. Additionally, Enterococcus isolates showed decreased susceptibility to ciprofloxacin and erythromycin. A control farm that employed coffee ground as a soil amendment, had the lowest abundance of bacteria in Zucchini squash bought from the farmers market. The indications of this study conflict with public perception of the safety of organic produce and may play a role in the development of awareness campaigns about the risks involved with farming practices (especially practices that include BSAAOs) and the handling of organic farmers’ market produce in the home.