Modelling of tetracycline resistance gene transfer by commensal Escherichia coli food isolates that survived in gastric fluid conditions.

Antimicrobial resistance (AR) is a major public health concern and a food safety issue worldwide. Escherichia coli strains, indicators of antibiotic resistance, are a source of horizontal gene transfer to other bacteria in the human intestinal system. A probabilistic exposure model was used to estimate the transfer of the AR gene tet(A). The acid resistance and kinetic behaviour of E. coli was analysed as a function of pH to describe the inactivation of E. coli in simulated gastric fluid (SGF), the major host barrier against exogenous micro-organisms. The kinetic parameters of microbial inactivation in SGF were estimated using GInaFiT, and log-linear + tail and Weibull models were found to be suitable for commensal and enterohaemorrhagic E. coli (EHEC), respectively. A probabilistic exposure model was developed to estimate E. coli survival in gastric pH conditions as well as gene transfer from resistant to susceptible cells in humans. E. coli-contaminated retail foods for consumption without further cooking and gastric pH data in South Korea were considered as an example. The model predicts that 22-33% of commensal E. coli can survive under gastric pH conditions of Koreans. The estimated total mean tet(A) transfer level by commensal E. coli was 1.68 × 10-4 -8.15 × 10-4 log CFU/mL/h. The inactivation kinetic parameters of E. coli in SGF and the quantitative exposure model can provide useful information regarding risk management options to control the spread of AR.