Survival of Escherichia coli in foods

Abstract

SUMMARY 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.

Variation in Acid Resistance among Shiga Toxin-Producing Clones of Pathogenic Escherichia coli

“…The consensus seems to be that E. coli O157:H7 is well suited to adverse conditions even though little direct evidence supports the hypothesis that this pathogen is substantially different from other E. coli serotypes in AR abilities (30). Most AR studies are based on only a few non-O157 STEC strains of the same serotype, which reduces the statistical power to detect significant differences between groups.…”

Effects of process severity on survival and growth of Escherichia coli and Listeria innocua on minimally processed vegetables

“…Non-pathogenic E. coli was used as a possible model for E. coli O157:H7. There have been no reports of significant differences in survival and growth characteristics between E. coli O157:H7 and nonpathogenic E. coli (McClure & Hall, 2000;Yokoigawa, Takikawa, & Kawai, 1999) in minimally processed vegetables (MPV). However, more evidence is needed to show that the strain used is an appropriate model i.e.…”

Variation in Stress Resistance Patterns among stx Genotypes and Genetic Lineages of Shiga Toxin-Producing Escherichia coli O157

“…In the human stomach, STEC O157 must survive the low pH of gastric fluid. In order to understand the ecology of STEC O157 and establish effective control measures against the bacterium, extensive research has been done on bacterial stress responses (5,24). Although some of these studies have shown the importance of cross-protection in stress resistance (5,20,33), the association between more than three types of stress has seldom been investigated.…”