Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 14, 2006
Publication Date: August 14, 2006
Citation: Sharma, M., Patel, J.R., Sulakvelidze, A., Mudd, C.L. 2006. Effectiveness of bacteriophage in reducing Escherichia coli O157:H7 on beef steaks and in ground beef slurries [abstract]. International Association for Food Protection Proceedings. p.130 Technical Abstract: A study was performed to evaluate the effectiveness of bacteriophage specific for Escherichia coli O157:H7 in killing the pathogen on beef steaks and in beef slurries stored at 4 deg C, 10 deg C and 37 deg C. Beef steaks (50 cm2) and ground beef slurries (300g) were either surface inoculated or inoculated and mixed with 3.3 log CFU/cm2 or 3.0 log CFU/g of E. coli O157:H7 B6914, respectively. A bacteriophage (EcoPhage, Intralytix, Inc.) was applied to steaks (7.3 PFU/cm2) or in slurries (6.3 log PFU/g), and steaks and slurries were stored at 4, 10 and 37 deg C for up to 7 d. Populations recovered from bacteriophage-treated steaks were 0.2 log CFU/cm2 lower than from control (no bacteriophage) steaks after 5 d at 4 deg C. Control slurries contained populations (2.5 log CFU/g) greater than in treated slurries (1.5 log CFU/g) after 7 d of storage at 4 deg C. Populations of E. coli O157:H7 on steaks (2.2 log CFU/cm2) and in slurries (1.9 log CFU/g) treated with bacteriophage were lower than on control steaks (3.2 log CFU/cm2) and in slurries (3.9 log CFU/g) when stored at 10 deg C for 5 d. After 7 d at 10 deg C, no cells were recovered by surface plating from treated slurries, while control slurries contained populations of 3.0 log CFU/g. Populations of E. coli O157:H7 on treated steaks were 0.5 log CFU/cm2 greater than on control steaks after 5 d at 37 deg C. Treated slurries incubated at 37 deg C for 3 d had populations 2 log CFU/g greater than those in control slurries. Storage of steaks and slurries at 10 deg C may promote limited growth of E. coli O157:H7, assisting in bacteriophage propogation and in increased killing of bacterial cells. More interaction between bacteriophage and bacterial cells may occur in ground beef slurries than on steaks, leading to greater reductions in populations of E. coli O157:H7 in slurries.