Phenotypic and genotypic characterization of listeria monocytogenes strains isolated from meat industries
- 1Department of Food Science and Technology, Faculty of Food Sciences, University of West Attica
- 2Department of Chemical Engineering, BioTeC + Chemical and Biochemical Process Technology and Control
Abstract
Listeria monocytogenes is a major foodborne pathogen of concern for the food industry due to its ability to persist in processing environments and contaminate ready-to-eat foods. This study aimed to characterize phenotypically and genotypically L. monocytogenes isolates recovered from meat-processing environments in Greece, with emphasis on antimicrobial susceptibility, resistance determinants, plasmid content, and sequence types. Eighteen environmental isolates were analyzed using broth microdilution MIC testing and Oxford Nanopore whole-genome sequencing followed by in silico screening for antimicrobial resistance genes and plasmids. All isolates were susceptible to ampicillin, erythromycin, and trimethoprim–sulfamethoxazole according to EUCAST criteria. For agents categorized by EUCAST as having insufficient evidence (“IE”) for clinical categorization in Listeria (moxifloxacin and linezolid), MICs were reported descriptively. Elevated MICs were observed for clindamycin (≥ 8 mg/L) in three isolates and for tetracycline (≥ 16 mg/L) in two isolates, while all isolates showed high fosfomycin MICs (≥ 128 mg/L) and intermediate fusidic acid MICs (4–8 mg/L). Genomic screening identified two acquired resistance genes, vga (G) and tet (M) , and detected plasmids in a subset of isolates, including plasmid types previously associated with stress tolerance and persistence in food environments. MLST revealed four sequence types (ST87, ST155, ST6, and ST504), including lineages linked to food-processing persistence and clinically relevant clonal complexes. Overall, the findings indicate limited clinically relevant resistance among the examined isolates, while highlighting the contribution of mobile genetic elements and diverse sequence types to environmental fitness and potential public-health risk in meat-processing settings.
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BibTeX
@article{vougiouklaki2026phenotypic,
title = {{Phenotypic and genotypic characterization of listeria monocytogenes strains isolated from meat industries}},
author = {Despina Vougiouklaki and Markos Dalezios and Konstantina Kyriakou and Marios Papaparaskevas and Marina Siouti and Simen Akkermans and Jan F. M. Impe and Efstathia Tsakali and Dimitra Houhoula},
journal = {Frontiers in Microbiology},
year = {2026},
month = oct,
doi = {10.3389/fmicb.2026.1922185},
url = {https://www.frontiersin.org/articles/10.3389/fmicb.2026.1922185/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Phenotypic and genotypic characterization of listeria monocytogenes strains isolated from meat industries
AU - Despina Vougiouklaki
AU - Markos Dalezios
AU - Konstantina Kyriakou
AU - Marios Papaparaskevas
AU - Marina Siouti
AU - Simen Akkermans
AU - Jan F. M. Impe
AU - Efstathia Tsakali
AU - Dimitra Houhoula
PY - 2026
DA - 2026/10/08
JO - Frontiers in Microbiology
DO - 10.3389/fmicb.2026.1922185
UR - https://www.frontiersin.org/articles/10.3389/fmicb.2026.1922185/full
AB - Listeria monocytogenes is a major foodborne pathogen of concern for the food industry due to its ability to persist in processing environments and contaminate ready-to-eat foods. This study aimed to characterize phenotypically and genotypically L. monocytogenes isolates recovered from meat-processing environments in Greece, with emphasis on antimicrobial susceptibility, resistance determinants, plasmid content, and sequence types. Eighteen environmental isolates were analyzed using broth microdilution MIC testing and Oxford Nanopore whole-genome sequencing followed by in silico screening for antimicrobial resistance genes and plasmids. All isolates were susceptible to ampicillin, erythromycin, and trimethoprim–sulfamethoxazole according to EUCAST criteria. For agents categorized by EUCAST as having insufficient evidence (“IE”) for clinical categorization in Listeria (moxifloxacin and linezolid), MICs were reported descriptively. Elevated MICs were observed for clindamycin (≥ 8 mg/L) in three isolates and for tetracycline (≥ 16 mg/L) in two isolates, while all isolates showed high fosfomycin MICs (≥ 128 mg/L) and intermediate fusidic acid MICs (4–8 mg/L). Genomic screening identified two acquired resistance genes, vga (G) and tet (M) , and detected plasmids in a subset of isolates, including plasmid types previously associated with stress tolerance and persistence in food environments. MLST revealed four sequence types (ST87, ST155, ST6, and ST504), including lineages linked to food-processing persistence and clinically relevant clonal complexes. Overall, the findings indicate limited clinically relevant resistance among the examined isolates, while highlighting the contribution of mobile genetic elements and diverse sequence types to environmental fitness and potential public-health risk in meat-processing settings.
SN - 1664-302X
ER -