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Phage “Angela” and the control of E. coli O157:H7 on meat

Phage “Angela” and the control of E. coli O157:H7 on meat. J. Andrew Hudson, Craig Billington, Angela Cornelius, Lucia Rivas, Stephen On, Nicola King, Salim Ismail. The state of play. Phages are increasingly being r ecognised as an effective control There are a few commercial products

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Phage “Angela” and the control of E. coli O157:H7 on meat

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  1. Phage “Angela” and the control of E. coli O157:H7 on meat J. Andrew Hudson, Craig Billington, Angela Cornelius, Lucia Rivas, Stephen On, Nicola King, Salim Ismail

  2. The state of play • Phages are increasingly being recognised as an effective control • There are a few commercial products • They are achieving recognition as • GRAS • Organic • Kosher • Processing aids

  3. The challenge of E. coli O157:H7 • O157:H7 is considered an adulterant in some kinds of meat exported to the US • The US market is very important to the NZ economy • Acceptable and effective controls don’t exist • Could we develop a phage cocktail that would inactivate E. coli O157:H7 on fresh meat ?

  4. Phage isolation Sample (e.g. screened sewage) Centrifuge and filter “sterilise” Add 0.1 ml sample to 0.1 ml host cells in soft agar Pour on to standard agar plate and incubate Check for plaques

  5. Host range of phage “Angela” • The range of taxa supporting phage replication • “Goldilocks” host range desirable • Angela infects: • 28/30 (93.3%) of E. coli O157 isolates • 1/30 (3.3%) other E. coli serotypes • 0/13 other foodborne species Photos by UoOtago EM Unit

  6. Absence of known stxgenes 1 2 1 kb ehxA534 eae384 stx2 255 stx1 180

  7. Effect on growing STEC O157

  8. A case study in pathogen control • Experiment on 2 x 2 cm pieces of beef (x3) • Add cells, allow attachment, add phages, incubate (37°C x 1 h), count survivors • Host cells • After attachment 1.41 x 104/piece • Alone 5.36 x 104/piece • With phages 4.3 x 101/piece (1 colony on 9 plates) • >99.9% (3 log10) reduction • Phages • Alone 2.64 x 106/piece • With host cells 2.40 x 106/piece

  9. Incubation time and control on meat

  10. Effect of phage concentration 1 hour 37°C

  11. On cooling meat

  12. On cooling meat 2

  13. Prospects and problems • More than 105phages/cm2 needed, better control at higher concentrations • Reasonable control under industry TT curves • Phage replication not important • Good host range • …..but not good enough • Regulations • Shifting goal posts: the “super seven”

  14. Acknowledgements • The meat industry (Meat and Wool New Zealand (now Beef+Lamb NZ), MIA) • New Zealand Foundation for Research, Science and Technology (now the Ministry of Business, Innovation and Employment). Contracts CO3X0201 and CO3X0701 • Rhys Jones of AgResearchfor beef cooling data • E. coli isolates were provided by ESR’s ERL • Electron Microscope Unit of the University of Otago for the electron micrographs

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