Prevalence of Enterobacteriaceae on fresh produce and food safety practices in small-acreage farms in Tennessee, USA

In spite of the health benefits acquired from produce, microbial safety continues to be a major concern. This study evaluated microbial quality of produce and food safety practices in small-scale farms. Microbial quality of produce from farms was determined by standard and biochemical techniques. Antimicrobial-susceptibility of bacteria was determined by Kirby-Bauer's disc diffusion method. In addition, questionnaires were developed and distributed to in Middle Tennessee, US growers to capture growers' practices on the farm. Aerobic plate counts in leafy produce and herbs (5.2-6.1 log CFU/g) were significantly higher (p < 0.05) than that of fruits (3.2-4.0 log CFU/g). Total coliforms in carrots (3.6 CFU/g) were also significantly higher (p < 0.05) than in lettuce (2.9/CFU/g), strawberries (2.5 CFU/g), and apples (2.1 CFU/g). Our results demonstrated that produce harbored diverse bacterial communities which were dominated by Escherichia coli (29.7%), followed by Serratia liquefacians (13%), Klebsiella pneumoniae (11.4%), Proteus mirabilis (10.8%), Pantoea spp. (8.1%), Salmonella (2.7%), Shigella (0.5%), among others. No Escherichia coli O157:H7 was recovered in produce. Bacterial resistance to antibiotics was highest for erythromycin (22.3%), followed by ampicillin (19.6%), streptomycin (12.8%), and amoxicillin (10.3%). About 9% of the farms had food safety plans in place, 31% tested irrigation water annually, and 93% of growers indicated the need for food safety education. Our results indicate that fresh produce from small farms harbor antibiotic resistant bacteria. Food safety education for growers is needed to cause positive changes in food safety awareness and increased adoption of good agricultural practices by small-scale produce growers.