Microbiological risk assessment and antibiotic resistance profiling of fresh produce from different soil enrichment systems : a preliminary study

This study assessed the microbial risk of fresh produce collected from a compost farm, a crop-livestock rotation farm and a traditional farm in Canterbury, New Zealand. A total of 79 vegetable samples were collected from 3 different farming systems. No Escherichia coli O157:H7 was detected, but 95, 92 and 44% of the samples from the organic farm had unsatisfactory aerobic plate count (APC), E. coli, and Staphylococcus aureus levels respectively compared to the traditional farm, with corresponding values of 66, 88 and 27% based on guidelines for ready-to-eat foods. Resistance profiling showed that S. aureus and Salmonella spp. from all farms showed a higher resistance to vancomycin, erythromycin, ampicillin and penicillin antibiotics. The fresh produce collected from the organic farms was more contaminated with a wider range of pathogens than those from the traditional farm. Since the consumer perception of organic produce is because of its 'chemical free' status with little regard to the microbial status, it is prudent to conduct further studies to determine the type(s) of microbial hazards and how they behave under different climatic conditions and also address bacterial resistance to antibiotics in farming environments.