Bacterial extracellular vesicles (EVs), small spherical membrane structures derived from bacterial cells, have emerged as key players in the interaction between bacteria and their surrounding environment. Their formation is regulated by complex biogenetic processes involving modifications of bacterial membranes and selective cargo loading. These vesicles, containing a wide range of biomolecules including lipids, proteins, nucleic acids, and metabolites, serve various fundamental biological functions including intercellular communication, molecular transport, and modulation of host response.

In the context of bacterial infections, bacterial EVs play a crucial role in pathogenesis, facilitating bacterial adhesion, invasion, and persistence within the host. Their molecular composition varies depending on the environmental context and the bacterial species involved, but often includes virulence factors, adhesive proteins, and bioactive molecules that influence the host immune response and infection progression. Bacterial extracellular vesicles can also act as carriers of antibiotic resistance, transporting enzymes capable of neutralizing antimicrobial agents and thereby contributing to the complexity of antibacterial therapy.

In the clinical setting, analysis of bacterial extracellular vesicles offers significant opportunities to improve the diagnosis and management of bacterial infections. Their presence in biological fluids can be used as a diagnostic biomarker, allowing for pathogen characterization and assessment of their virulence and antimicrobial resistance. Furthermore, extracellular vesicles represent a promising therapeutic target, as interference with their formation or function can hinder bacterial virulence and enhance the efficacy of existing antimicrobial therapies.

Recently, research attention has also extended to extracellular vesicles produced by archaea (Archaeal Extracellular Vesicles, AEV). Archaea, microorganisms known for their ability to inhabit extreme environments, release vesicles that share many characteristics with bacterial ones but also possess unique specificities due to the peculiar composition of their membranes and molecular content. AEVs are involved in cell communication, nutrient acquisition, and responses to environmental stress. Their potential role in modulating microbiota-host interactions and antimicrobial resistance is an emerging field of great interest, with possible implications for biomedicine and biotechnology.

In conclusion, the importance of bacterial and archaeal extracellular vesicles in clinical microbiology is increasingly recognized, offering new perspectives for understanding and treating infections. Deepening our knowledge of the mechanisms of formation, composition, and function of these vesicles is a research priority, with potential implications for clinical practice and the development of new therapeutic strategies.

References

Xie J, Li Q, Haesebrouck F, Van Hoecke L, Vandenbroucke RE. The tremendous biomedical potential of bacterial extracellular vesicles. Trends Biotechnol. 2022 Oct;40(10):1173-1194. doi: 10.1016/j.tibtech.2022.03.005. Epub 2022 May 14. PMID: 35581020.

Liu J, Cvirkaite-Krupovic V, Commere PH, Yang Y, Zhou F, Forterre P, Shen Y, Krupovic M. Archaeal extracellular vesicles are produced in an ESCRT-dependent manner and promote gene transfer and nutrient cycling in extreme environments. ISME J. 2021 Oct;15(10):2892-2905. doi: 10.1038/s41396-021-00984-0.