Purpose: The objectives of this study were to isolate E. coli O157:H7 and to determine the presence of stx1 and stx2 genes of E. coli O157:H7 from cilantro, green onion, spinach, alfalfa sprouts, and lettuce collected from the local market.
Methods: Fresh produce consisting of cilantro, green onion, spinach, alfalfa sprouts and lettuce were collected. The total numbers of samples collected were 455, and the samples were analyzed for the presence of E. coli O157:H7, stx1 and stx2 genes. The strains were isolated and identified according to the procedures of the Bacteriological Analytical Manual with some modification to identify the presence of E. coli O157:H7. DNAs were extracted using PrepSEQ Rapid Spin Sample Preparation Kit according to the manufacturer’s instructions, and then PCR, Gel electrophoresis, Serotyping, and Pulsed-Field Gel Electrophoresis assays were performed to confirm the presence of E. coli O157:H7.
Results: Biochemical and serological analysis showed that 33 (7%) isolates were confirmed to be E. coli O157:H7. Out of them 36.4%, 33.3%, 18.18%, 6.06%, and 6.06% were isolated from cilantro, green onion, spinach, sprouts, and lettuce samples, respectively. Results also indicated that twenty-three (70%) of the presumptive positive samples carried the virulence genes of stx1 or stx2, ten (30%) of the presumptive samples showed no virulence genes amplification.
Significance: Outcomes of this project showed that E. coli O157:H7 can be found on the surface of the produce. Thus, to provide safe fresh produce to the consumer, a novel approach using bioactive compounds as well as a rapid and close monitoring system needs to be implemented.