High-pressure processing (HPP) alters tetracycline resistance in Listeria monocytogenes: A phenotypic and genotypic study

This study insights into the effects of high-pressure processing (HPP) on the phenotypic resistance and expression of tetracycline resistance genes ( tetA _1, tetA _2, tetA _3, tetC , tetR ) in Listeria monocytogenes strains. A total of 29 strains were tested for minimum inhibitory concentration values (MIC) of tetracycline before and after HPP treatment (200 MPa/5 min). Results showed a significant increase in MIC values post-treatment, with 7 % of the strains exhibiting resistance. Gene expression analysis revealed overexpression of tetA _1 and tetA _2 genes, while tetA _3, tetC , and tetR showed varied responses, suggesting a strain specific expression pattern. These findings indicate that HPP induced stress may influence the development of antibiotic resistance in L. monocytogenes , highlighting the importance of monitoring resistance genes in food safety protocols.