Foodborne Bacterial Pathogens, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK. mark.alston@bbsrc.ac.uk|Foodborne Bacterial Pathogens, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK. mark.alston@bbsrc.ac.uk|Foodborne Bacterial Pathogens, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK. mark.alston@bbsrc.ac.uk|Foodborne Bacterial Pathogens, Institute of Food Research, Norwich Research Park, Norwich, NR4 7UA, UK. mark.alston@bbsrc.ac.uk