Predictive Modeling of Uropathogenic Escherichia Coli in Ready-To-Eat Meats

Annually around 150 million people worldwide suffer from urinary tract infection (UTI), of which about 75% are caused by uropathogenic Escherichia coli (UPEC). To elevate public health, it is a global and urgent task to find out how to prevent or control the exposure of UPEC in humans. The influence of foodborne illness used to be expected to occur in the intestinal system only. However, recent studies have shown that meat is potential to be a food reservoir of UPEC and may cause foodborne UTIs. It is reasonable to assume that when consumers handle the meat inappropriately, they will expose to the risk of FUTI due to contact and ingestion. In this study, we sampled raw chicken (n=25), pork (n=22), and beef (n=20) from traditional markets and supermarkets, as well as ready-to-eat chicken (n=10), pork (n=10) and beef (n=10) from convenience stores, restaurants, and hypermarkets, and the sampling was between January to October 2021. The prevalence rate of UPEC in fresh meat was 18%, and chicken is the highest (22.6%), followed by pork (14.6%) and beef (13.9%). Then, we established the growth modeling for UPEC in raw and cooked beef. A cocktail of UPEC isolates were inoculated in beef chucks and isothermally incubated at 4, 10, 20, 25 and 35℃ to obtain the growth courves. The growth curves were submitted to the USDA IPMP, and the statistical indices showed that the combination of the no lag phase and Huang square-root models was better than the others. The validation results at 30℃ showed that predicted values of UPEC growth by the corresponding models were fairly close to the observed values (RMSE, 0.37-0.45; adjusted R2, 0.96-0.97; pRE, 0.88). The models can quantify the microbial growth behavior of UPEC in fresh and ready-to-eat beef at different temperatures and times, which is beneficial to food control and the establishment of quantitative microbial risk assessment. In addition, we chose chicken with the highest risk of foodborne UTI from the consumer’s perspective to establish inactivation modeling of UPEC in chicken breast with or without salt marinade via sous-vide treatment at 50, 55, 60, and 63°C to evaluate the behavior of UPEC. We used the Liner model as the primary model and the thermal death time curve as the secondary model to construct the predictive inactivation model. We also constructed the survival curve at 58°C for external validation. The results showed that all the models for all treatments fitted well with UPEC survival curves (RMSE, 0.12-0.13; adjusted R2, 0.98; pRE, 0.75-0.88). Salt marination is an effective hurdle and made UPEC more sensitive to the lethal effect of heat, resulting in lower D-values and a greater reduction in UPEC population in NaCl-treated chicken breast under the sous-vide process. Consequently, combining salt marinade and sous-vide cooking can provide safer sous-vide ready-to-eat (RTE) food. The thermal inactivation model based on the Linear model of UPEC in the chicken breast during sous-vide cooking can be a tool for controlling microbial hazards and for exposure assessment to prevent future foodborne UTIs.