Impact of the defined Oligo-MM12 microbiota on intestinal colonisation and dissemination of Listeria monocytogenes
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Date
2026-03-09
Authors
Cazzaniga, Monica
Bra, Kardokh Kaka
Herzog, Mathias K. M.
Hardt, Wolf-Dietrich
Claesson, Marcus J.
Mathur, Harsh
Gahan, Cormac G. M.
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Abstract
Listeria monocytogenes is a foodborne pathogen of global concern, particularly for immunocompromised individuals at risk of severe disease. In mice, infection outcomes are strongly influenced by host immunity and gut microbiome composition. The Oligo-MM12 defined microbiota mouse model, containing a simplified community of 12 bacterial strains, offers a controlled system to study L. monocytogenes pathogenesis and microbiome interactions. Defined or reduced-complexity microbiota models are increasingly used to investigate colonisation resistance and identify protective taxa. In this study, we compared Oligo-MM12 mice with conventionally raised Specific Pathogen Free (SPF) mice to assess how microbiome complexity shapes infection. This allowed us to explore how microbiome complexity affects resistance to L. monocytogenes. We performed an in vivo infection study to assess host responses and pathogen-related outcomes, alongside an ex vivo fermentation assay that simulated the murine distal colon, to monitor microbial dynamics. Building on our earlier work, we now demonstrate that in vivo, Oligo-MM12 mice showed significantly higher L. monocytogenes shedding in faeces during infection, whereas SPF mice progressively reduced L. monocytogenes levels. Despite this, L. monocytogenes dissemination to internal organs after three days of infection was similar in both models. Alterations to gut Prevotella, Akkermansia and Blautia species following L. monocytogenes infection were noteworthy. Ex vivo fermentation mirrored in vivo patterns, validating the Oligo-MM12 system for mechanistic studies. Together, these results highlight the importance of microbiome complexity in modulating infection outcomes and establish a foundation for identifying protective taxa and mechanisms of colonization resistance.
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© 2026, the Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
Keywords
Animals , Listeria monocytogenes/pathogenicity , Gastrointestinal microbiome , Listeriosis/microbiology , Mice , Disease models, animal , Feces/microbiology , Specific pathogen-free organisms , Mice, inbred C57BL , Female , [Microbiology]
Citation
Cazzaniga, M, Bra, K K, Herzog, M K M, Hardt, W-D, Claesson, M J, Mathur, H & Gahan, C G M 2026, 'Impact of the defined Oligo-MM12 microbiota on intestinal colonisation and dissemination of Listeria monocytogenes', Scientific Reports, vol. 16, no. 1, 8434, pp. 1-15. https://doi.org/10.1038/s41598-026-37294-4
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