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.