Abstract
Escherichia coli strains produce Shiga-toxins Stx-1 and Stx-2 that contribute to their virulence. The objective was to evaluate antimicrobial activities of plant essential oils (oregano, cinnamon, lemongrass), their active components (carvacrol, cinnamaldehyde, citral) and plant-extracts (green tea polyphenols, apple skin, black tea, decaffeinated black tea, grapeseed and pomace extracts) against E. coli O157:H7 strains containing Stx-1 and Stx-2 genes, as determined by Multiplex Polymerase Chain Reaction, in vitro and on leafy greens. Antimicrobials at various concentrations in sterile PBS were added to bacterial cultures (~3 - 4 logs CFU/ml), mixed thoroughly, and incubated at 37°C. Surviving bacteria were enumerated at 0, 1, 3, 5 and 24 h. The most effective essential oil (oregano oil; 0.5%) and plant extract (green tea; 3%) were evaluated against E. coli O157:H7 on romaine lettuce and spinach stored at 4°C for 7 days. Microbial survival was a function of the concentration of antimicrobials and incubation times. All antimicrobials reduced bacterial population to below detection levels in vitro; however, essential oils and active components exhibited greater activity than plant extracts. Oregano oil and green tea reduced E. coli O157:H7 on lettuce and spinach to below detection. Plant-based antimicrobials have the potential to protect foods against E. coli O157: <span style="fo
Highlights
Escherichia coli O157:H7 is one of the most important foodborne pathogenic bacterium responsible for hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) in affected individuals
Virulent E. coli O157:H7 is characterized by the presence of Stx-1, Stx-2, intimin, and ehxA genes [13]
The following E. coli O157:H7 strains were selected for evaluation: 932, ATTC 35150, and F4637, isolated from humans, humans, and sprouts, respectively
Summary
Escherichia coli O157:H7 is one of the most important foodborne pathogenic bacterium responsible for hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS) in affected individuals. According to Marshall, et al [1], Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes are the leading causes of multistate foodborne disease outbreaks in the United States. According to Smith, et al [2], STEC are foodborne pathogens that may cause diarrheal outbreaks and occasionally are associated with HUS. E. coli O157:H7 has caused numerous foodborne outbreaks (via undercooked hamburger patties, apple cider, spinach, lettuce, etc.) and is associated with causing HUS in young children and the elderly. Virulent E. coli O157:H7 strains are known to produce the Shiga toxins Stx-1 and Stx-2. Beef cattle are one of the major reservoirs and illnesses have been reported to be contracted by visiting farms or eating undercooked hamburgers [5] [6] [7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
