Potential for Bacteriophage Cocktail to Complement Commercial Sanitizer Use on Produce against Escherichia coli O157:H7

Abstract

The increasing concern for food safety has created a need to evaluate novel techniques to eliminate or control pathogens, resulting in safe food. In this study, four bacteriophages of bovine origin, specific to E. coli O157:H7, were successfully isolated and characterized. A microplate reader assay demonstrated the efficacy of the bacteriophage (phage) cocktail against E. coli O157:H7 resulting in a significant reduction (p < 0.01) in the target pathogen population. The phage cocktail demonstrated significant efficacy (p < 0.05) against E. coli O157:H7 in the presence of the most utilized sanitizers in the United States, namely 100 parts per million (ppm) free chlorine and 100-ppm peroxyacetic acid. Survival in the sanitizer concentrations demonstrates the potential use of phage cocktail and sanitizer synergistically to enhance sanitation operations in the food industry.

Efficacy of Bacteriophage Cocktail to Control E. coli O157:H7 Contamination on Baby Spinach Leaves in the Presence or Absence of Organic Load

“…Because phages are ubiquitous, the isolation of new phages specific to the pathogen that exhibits a difference in the attachment mechanism can be used to update phage cocktails and make them effective against the development of phage-resistant mutant strains. Although the use of bacteriophages requires that investigators exercise caution to ensure their specificity against the target pathogen, the bacteriophage cocktails used in this study have been previously investigated for their specificity and also have demonstrated infectivity only for E. coli O157:H7 strains [ 19 ].…”

“…Therefore, increasing the phage concentration might help achieve a more significant reduction of the pathogen during produce wash. Environmental conditions can also play a significant role in a phage’s viability; thus, studying the effect of these conditions will help to ensure the continuous performance of the phage against the pathogen. Phages employed for this study have also been shown to be resistant to 100-ppm chlorine and 100-ppm SaniDate 5.0 for up to 3 h [ 19 ]. Thus, developing a multilevel sanitation system that employs both a sanitizer and bacteriophage combination might be one of the solutions to reduce pathogen contamination on fresh produce.…”

“…The host strain for all the bacteriophages was E. coli O157:H7 (ATCC 35150). The phage titer was approximately 10 9 plaque-forming units (PFU)/mL for the phage cocktail [ 19 ]. Equal numbers of individual bacteriophage types were mixed in a sterile test tube, and the required volume was pipetted to make the phage cocktail right before every experiment.…”

“…One hundred microliters of bacteriophage cocktail was added to the wells and mixed by aspiration using a multi-channel micro-pipette, which contributed to a multiplicity of infection (MOI) of 1. Using a microplate reader (BioTek, Synergy 4, Winooski, VT, USA), the turbidity analysis settings were developed from a previously determined procedure [ 19 ]. The settings for the turbidity analysis were as follows: temperature of 37 °C (range: 36.5–37 °C), number of flashes as 1, measurement mode as absorbance, measurement wavelength of 660 nm, start kinetic (run: 3:00:00, interval 00:30:00), shake duration (orbital) of 10 s (s), shake intensity as medium, total measurement time of 24 h, and unit as optical density (OD).…”

Low-Temperature Virus vB_EcoM_VR26 Shows Potential in Biocontrol of STEC O26:H11

“…The association of STEC with produce presents a serious problem because these products are minimally processed. Moreover, STEC strains have been shown to be adapted to survive for prolonged periods on plants and are often resistant to washing and chemical sanitizers [ 5 , 6 , 7 , 8 ]. As a result, contamination of fresh produce is emerging as a major food safety challenge, suggesting that current strategies to control microbial population during the production of fresh produce do not guarantee the elimination of STEC [ 2 , 8 , 9 , 10 , 11 , 12 ].…”