Ciprofloxacin-resistant variants of Listeria monocytogenes EGD-e show increased heat resistance in buffer and milk

Martínez de Zuazo, María Mei (Universidad de Zaragoza) ; Andaluz-Arbe, Jorge (Universidad de Zaragoza) ; Fau, Alberto (Universidad de Zaragoza) ; García-Penas, Ivo (Universidad de Zaragoza) ; Pagán, Rafael (Universidad de Zaragoza) ; García-Gonzalo, Diego (Universidad de Zaragoza) ; Merino, Natalia (Universidad de Zaragoza)

Resumen: 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.

Idioma: Inglés

DOI: 10.1016/j.afres.2026.101933

Año: 2026

Publicado en: Applied food research 6, 1 (2026), 101933 [10 pp.]
ISSN: 2772-5022

Financiación: info:eu-repo/grantAgreement/ES/DGA/A06-23R
Financiación: info:eu-repo/grantAgreement/ES/MCIU/PID2021-123404NB-I00
Financiación: info:eu-repo/grantAgreement/ES/MICINN PRE2022-102372

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Nutrición Bromatología (Dpto. Produc.Animal Cienc.Ali.)
Área (Departamento): Área Tecnología de Alimentos (Dpto. Produc.Animal Cienc.Ali.)