Pathogenic Mechanisms of Acinetobacter Baumannii Infections

Acinetobacter baumannii has emerged as an opportunistic Gram-negative pathogen with a remarkable capacity to cause severe hospital-acquired and community-acquired infections. Its pathogenic success is underpinned by a combination of adaptive features: the secretion of outer membrane vesicles (OMVs) that deliver toxins and modulate host responses; the ability to survive within professional and non-professional phagocytes by subverting phagosomal maturation; and the manipulation of host signalling pathways, including the aryl hydrocarbon receptor (AHR) axis, to induce cytotoxic transcriptional programmes. Nutrient acquisition systems and surface-associated proteins facilitate adhesion to epithelial surfaces and biofilm formation, promoting persistence on abiotic surfaces and within host tissues. Concurrently, A. baumannii evades innate immune effectors by resisting oxidative and antimicrobial peptide-mediated killing, impairing inflammasome activation and altering cytokine release. Genetic and phenotypic heterogeneity among clinical isolates further complicates the prediction of virulence traits, driving the need for standardised models and targeted therapeutic strategies. Collectively, these mechanisms converge to enable A. baumannii to colonise, invade and damage host tissues, establishing a framework for the development of novel anti-virulence and immunomodulatory interventions.

Research from Nature Portfolio

Recent studies have revealed how A. baumannii OMVs induce host cell cytotoxicity via a novel metabolic–transcriptional axis. Infection with clinical strains leads to the secretion of OMVs that activate the host enzyme tryptophan-2,3-dioxygenase, increasing production of the AHR ligand kynurenine. Ligand binding to AHR triggers transcriptional upregulation of the FOS gene, a key mediator of cell death. Pharmacological inhibition of FOS or genetic disruption of AHR signalling markedly reduces cytotoxicity in cell culture and animal models. This work highlights the interplay between bacterial vesicle-mediated delivery of metabolites and host transcription factors as a critical factor in tissue injury and disease progression.

Pathogenic Mechanisms of Acinetobacter Baumannii Infections publication trend

The graph below shows the total number of articles in pathogenic mechanisms of acinetobacter baumannii infections across all publications each year (not limited to Nature Index journals).

Technical terms

Outer membrane vesicles (OMVs): Nanoscale blebs released from the bacterial outer membrane that carry proteins, lipids and toxins to host cells.

Aryl hydrocarbon receptor (AHR): A ligand-activated transcription factor that regulates genes in response to environmental and microbial metabolites.

Phagosome: A membrane-bound compartment formed around engulfed particles or pathogens within phagocytic cells.

Inflammasome: A multiprotein complex in innate immune cells that activates inflammatory caspases and cytokine maturation in response to pathogens and damage signals.

References

1. The aryl hydrocarbon receptor and FOS mediate cytotoxicity induced by Acinetobacter baumannii. Nature Communications (2024).
2. The intracellular life of Acinetobacter baumannii. Trends in Microbiology (2023).
3. Replicative Acinetobacter baumannii strains interfere with phagosomal maturation by modulating the vacuolar pH. PLOS Pathogens (2023).