Comparative characterization of Listeria monocytogenes strains isolated from plant and animal-derived foods for their virulence, biofilm formation and antibiotic susceptibility.

Authors

Niveditha Pollumahanti, Sukhadeo B Barbuddhe, Deepak B Rawool, Koigoora Srikanth

Published in

Archives of microbiology. Volume 208. Issue 10. Jul 21, 2026. Epub Jul 21, 2026.

Abstract

Listeriosis caused by Listeria monocytogenes is an important emerging foodborne disease worldwide and possesses remarkable environmental adaptability, enabling its evolution under diverse host and environmental conditions. To address this, the present study investigated the occurrence, virulence potential, biofilm-forming ability, and antimicrobial resistance profiles of L. monocytogenes isolated from animal- and plant-derived foods collected from four states of India during 2023-2025. A total of 941 food samples, comprising animal-derived foods (n = 690) and plant-derived foods (n = 251), were analyzed using EN ISO 11290-1:2017 protocols, VITEK^® 2 identification, and duplex PCR confirmation. Overall, 21 isolates (2.23%) were confirmed as L. monocytogenes, with higher positivity observed in plant-derived foods (3.59%) compared to animal-derived foods (1.74%). All isolates harboured major virulence-associated genes (plcA, prfA, hlyA, actA, and inlC). Animal-derived isolates exhibited significantly higher virulence characteristics, including stronger hemolytic activity, earlier PI-PLC expression, and greater lethality in the G. mellonella larvae compared to plant-derived isolates. Biofilm biomass also increased significantly with incubation time in both groups of isolates; however, the magnitude of biofilm formation differed significantly (p = 0.001) between the two groups of isolates. Antimicrobial susceptibility testing revealed multidrug resistance among isolates from both sources; however, plant-derived isolates exhibited a more uniform resistance pattern, while animal-derived isolates showed greater variability. The findings highlight that the source of isolation of L. monocytogenes plays a significant role in shaping the virulence, biofilm formation, and antimicrobial resistance characteristics of the isolates, and hence warrant studies to understand how environmental and host-specific conditions can influence the adaptive evolution and pathogenic potential of microbial isolates.

PMID:
42479250
Bibliographic data and abstract were imported from PubMed on 21 Jul 2026.

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