Effect of phage and host concentration on the inactivation of Escherichia coli O157:H7 on cooked and raw beef

• Published in: Food science and technology international 2015-03, Vol.21 (2), p.104-109
• Main Authors: Hudson, JA, Billington, C, Wilson, T, On, SLW
• Format: Article
• Language: English
• Subjects: Animals; Bacteriophages; Cattle; Colony Count, Microbial; Cooking; Escherichia coli; Escherichia coli O157 - growth & development; Food Handling - methods; Food Microbiology; Food Preservation - methods; Food Storage; Humans; Microbial Viability; Red Meat - microbiology; Temperature
• ISSN: 1082-0132; 1532-1738
• DOI: 10.1177/1082013213513031

A previously described phage infecting Escherichia coli O157:H7 was added to raw and cooked beef pieces at concentrations ranging from 101–108 plaque forming units/cm2 to either low (4 log10 CFU/cm2 at both temperatures could be achieved compared to phage-free controls. There was a trend for greater inactivation to occur with increasing phage concentration. While re-growth of surviving cells occurred in nearly all samples incubated for 24 h at 24℃, these conditions are not typical of those experienced by perishable foods. It was concluded that phages can be used to reduce the concentration of a bacterial pathogen on meat, but the concentration of phages needs to be high (>4–5 log10 plaque forming units/cm2) for reductions to occur. A concentration of the order 8 log10 plaque forming units/cm2 was needed to achieve a 4 log10 CFU/cm2 reduction.