170386 20260420103354.0 doi 10.1016/j.afres.2026.101933 sideral 148885 ART-2026-148885 eng Martínez de Zuazo, María Mei Universidad de Zaragoza Ciprofloxacin-resistant variants of Listeria monocytogenes EGD-e show increased heat resistance in buffer and milk 2026 The extensive use of antibiotics in primary production has promoted the emergence of resistant bacteria. Due to cross-protection phenomena, these antimicrobial resistant (AMR) bacteria may also withstand food preservation treatments applied in the food industry. This study aimed to evaluate the emergence of resistant variants (RVs) of Listeria monocytogenes EGD-e after prolonged exposure to antibiotics (amoxicillin, ciprofloxacin and oxytetracycline) based on adaptive laboratory evolution assays. RVs were selected by determining the minimum inhibitory concentration, then characterized phenotypically against heat treatments (58 °C/ 20 min) and genotypically to identify mutations responsible for changes in thermoresistance. Five ciprofloxacin RVs (LmCip1–5) and one oxytetracycline RV (LmOxy) were obtained. Several ciprofloxacin RVs showed greater thermoresistance in McIlvaine buffer (pH 7.0) than the parental strain, also observed in skimmed milk (pH 6.8). Mutations identified in codY (LmOxy) and fepR and parC (ciprofloxacin RVs) are likely responsible for the antibiotic resistance. Moreover, mutations in genes linked to cell wall biosynthesis (rml), metabolism and RNA or energy processing (e.g., cshA, atpA2, lmo2794) may contribute to increased thermoresistance. These findings highlight the interaction between AMR and cross-protections mechanisms, and the potential risk posed by AMR bacteria in the food chain, which could compromise the traditional preservation methods. Access copy available to the general public Unrestricted info:eu-repo/grantAgreement/ES/DGA/A06-23R info:eu-repo/grantAgreement/ES/MCIU/PID2021-123404NB-I00 info:eu-repo/grantAgreement/ES/MICINN PRE2022-102372 info:eu-repo/semantics/openAccess by https://creativecommons.org/licenses/by/4.0/deed.es info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Andaluz-Arbe, Jorge Universidad de Zaragoza Fau, Alberto Universidad de Zaragoza (orcid)0009-0008-1441-1683 García-Penas, Ivo Universidad de Zaragoza (orcid)0000-0002-6598-8879 Pagán, Rafael Universidad de Zaragoza (orcid)0000-0002-0238-6328 García-Gonzalo, Diego Universidad de Zaragoza (orcid)0000-0002-7629-8101 Merino, Natalia Universidad de Zaragoza (orcid)0000-0003-4774-0973 2008 640 Universidad de Zaragoza Dpto. Produc.Animal Cienc.Ali. Área Nutrición Bromatología 2008 780 Universidad de Zaragoza Dpto. Produc.Animal Cienc.Ali. Área Tecnología de Alimentos 6, 1 (2026), 101933 [10 pp.] Applied food research 2772-5022 999530 http://zaguan.unizar.es/record/170386/files/texto_completo.pdf Versión publicada 2561569 http://zaguan.unizar.es/record/170386/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:170386 articulos driver 2026-04-18-10:48:32 ARTICLE