Survival of Escherichia coli in foods

Studies describing the survival of Escherichia coli in foods, more often than not use the O157:H7 serovar as the target organism. Whilst E. coli O157:H7 is undoubtedly the predominant agent of concern for foodborne disease caused by enterohaemorrhagic E. coli (EHEC), a consequence of this concern is the commonly held view that this one serovar is 'atypical' in its response to stress conditions and therefore better able to survive adverse environments. Many of the studies published do not make comparisons with other E. coli (either commensal organisms or other pathogenic types) or other members of the Enterobacteriaceae, that would justify this view. Nevertheless, there has been a great deal of valuable data and information generated describing the fate of E. coli O157:H7 in a range of foods stored under various conditions. In many respects, the results of these studies are not surprising considering the survivability of other closely related pathogens, such as Shigella spp. This ability to survive in foods for long periods of time confirms the need for reliable control measures where contamination is possible or likely, e.g. proper handling and thorough cooking of beefburgers. The factors that may influence survival in different foods are described, with the intention of providing an insight in this area of food safety. Key considerations for carrying out survival studies are identified, with particular reference to methodologies used.