A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections

Abstract Acinetobacter baumannii causes prolonged infections that disproportionately affect immunocompromised populations. Our understanding of A. baumannii respiratory pathogenesis relies on an acute murine infection model with limited clinical relevance that employs an unnaturally high number of b...

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Main Authors: Clay D. Jackson-Litteken, Gisela Di Venanzio, Manon Janet-Maitre, Ítalo A. Castro, Joseph J. Mackel, Leslie D. Wilson, David A. Rosen, Carolina B. López, Mario F. Feldman
Format: Article
Language:English
Published: Nature Portfolio 2025-08-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-62655-4
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author Clay D. Jackson-Litteken
Gisela Di Venanzio
Manon Janet-Maitre
Ítalo A. Castro
Joseph J. Mackel
Leslie D. Wilson
David A. Rosen
Carolina B. López
Mario F. Feldman
author_facet Clay D. Jackson-Litteken
Gisela Di Venanzio
Manon Janet-Maitre
Ítalo A. Castro
Joseph J. Mackel
Leslie D. Wilson
David A. Rosen
Carolina B. López
Mario F. Feldman
author_sort Clay D. Jackson-Litteken
collection DOAJ
description Abstract Acinetobacter baumannii causes prolonged infections that disproportionately affect immunocompromised populations. Our understanding of A. baumannii respiratory pathogenesis relies on an acute murine infection model with limited clinical relevance that employs an unnaturally high number of bacteria and requires assessment of bacterial load at 24-36 h post-infection. Here, we demonstrate that low intranasal inoculums in tlr4 mutant mice allows for infections lasting at least 3 weeks. Using this “chronic infection model” we determine the adhesin InvL is a virulence factor required during later stages of infection, despite being dispensable in the early phase. We also demonstrate that the chronic model enables distinction between antibiotics that, although initially reduce bacterial burden, either lead to clearance or result in the formation of potential bacterial persisters. To illustrate how our model can be applied to study polymicrobial infections, we inoculate mice with an active A. baumannii infection with Staphylococcus aureus or Klebsiella pneumoniae. We find that S. aureus exacerbates infection, while K. pneumoniae enhances A. baumannii clearance. In all, the chronic model overcomes some limitations of the acute pulmonary model, expanding our capabilities to study A. baumannii pathogenesis and lays the groundwork for the development of similar models for other opportunistic pathogens.
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spelling doaj-art-36aff2e50ad5437cb3e166e3df4f08992025-08-20T03:05:14ZengNature PortfolioNature Communications2041-17232025-08-0116111410.1038/s41467-025-62655-4A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infectionsClay D. Jackson-Litteken0Gisela Di Venanzio1Manon Janet-Maitre2Ítalo A. Castro3Joseph J. Mackel4Leslie D. Wilson5David A. Rosen6Carolina B. López7Mario F. Feldman8Department of Molecular Microbiology, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineDepartment of Pediatrics, Division of Infectious Diseases, Washington University School of MedicineDivision of Comparative Medicine, Research Animal Diagnostic Laboratory, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineDepartment of Molecular Microbiology, Washington University School of MedicineAbstract Acinetobacter baumannii causes prolonged infections that disproportionately affect immunocompromised populations. Our understanding of A. baumannii respiratory pathogenesis relies on an acute murine infection model with limited clinical relevance that employs an unnaturally high number of bacteria and requires assessment of bacterial load at 24-36 h post-infection. Here, we demonstrate that low intranasal inoculums in tlr4 mutant mice allows for infections lasting at least 3 weeks. Using this “chronic infection model” we determine the adhesin InvL is a virulence factor required during later stages of infection, despite being dispensable in the early phase. We also demonstrate that the chronic model enables distinction between antibiotics that, although initially reduce bacterial burden, either lead to clearance or result in the formation of potential bacterial persisters. To illustrate how our model can be applied to study polymicrobial infections, we inoculate mice with an active A. baumannii infection with Staphylococcus aureus or Klebsiella pneumoniae. We find that S. aureus exacerbates infection, while K. pneumoniae enhances A. baumannii clearance. In all, the chronic model overcomes some limitations of the acute pulmonary model, expanding our capabilities to study A. baumannii pathogenesis and lays the groundwork for the development of similar models for other opportunistic pathogens.https://doi.org/10.1038/s41467-025-62655-4
spellingShingle Clay D. Jackson-Litteken
Gisela Di Venanzio
Manon Janet-Maitre
Ítalo A. Castro
Joseph J. Mackel
Leslie D. Wilson
David A. Rosen
Carolina B. López
Mario F. Feldman
A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
Nature Communications
title A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
title_full A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
title_fullStr A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
title_full_unstemmed A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
title_short A chronic Acinetobacter baumannii pneumonia model to study long-term virulence factors, antibiotic treatments, and polymicrobial infections
title_sort chronic acinetobacter baumannii pneumonia model to study long term virulence factors antibiotic treatments and polymicrobial infections
url https://doi.org/10.1038/s41467-025-62655-4
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