Survival Pattern of Enterohemorrhagic Escherichia coli Strain (CDC05) in Sterile Ground Beef Medium Under Different Physicochemical Conditions

The survival pattern of Escherichia coli O157:H7, an important foodborne pathogen of the enterohemorrhagic E. coli (EHEC) category, in different physicochemical conditions related to food storage, was evaluated in the study. The persistence of E. coli O157:H7 under conditions varying in salt concentration (0-12% w/v), pH levels (2-12), and storage temperatures encompassing ambient (28±2°C), refrigeration condition (4°C), and freezer condition (-18°C) conditions in sterile ground bovine meat medium was assessed. A mathematical model developed in the MATLAB analytical tool was used to study the survival kinetics of the pathogen across diverse stress conditions. It was observed that no viable cells were recovered after one week of freezing and two months of refrigeration. The shortest observed D-values for EHEC cells were 1.54 days at pH 12, 5.47 days at freezing temperature, and 26.72 days at refrigeration temperature in the sterile beef medium. Notably, E. coli O157:H7 exhibited prolonged viability exceeding thirty days under most stress conditions examined, indicating heightened resistance and persistence. The mathematical model demonstrated reliability in approximating survival durations and, thus served as a valuable predictive tool for risk assessment in various food processing steps, thereby ensuring effective management of foodborne pathogens.