Acinetobacter defence mechanisms against biological aggressors and their use as alternative therapeutic applications

Abstract

Several Acinetobacter strains are important nosocomial pathogens, with Acinetobacter baumannii being the species of greatest worldwide concern due to its multi-drug resistance and the recent appearance of hyper-virulent strains in the clinical setting. Colonisation of this environment is associated with a multitude of bacterial factors, and the molecular features that promote environmental persistence in abiotic surfaces, including intrinsic desiccation resistance, biofilm formation and motility, have been previously addressed. On the contrary, mechanisms enabling Acinetobacter spp. survival when faced against other biological competitors are starting to be characterised. Among them, secretion systems (SS) of different types, such as the T5bSS (Contact-dependent inhibition systems) and the T6SS, confer adaptive advantages against bacterial aggressors. Regarding mechanisms of defence against bacteriophages, such as toxin-antitoxin, restriction-modification, Crispr-Cas and CBASS, among others, have been identified but remain poorly characterised. In view of this, we aimed to summarise the present knowledge on defence mechanisms that enable niche establishment in members of the Acinetobacter genus. Different proposals are also described for the use of some components of these systems as molecular tools to treat Acinetobacter infections.

Keywords:

• Type-5 secretion system
• type-6 secretion system
• contact-dependent inhibition
• Crispr
• Cas
• Brex
• toxin
• virulence factor
• bacteriophage

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Acknowledgements

The authors thank Dr. Suzana Salcedo, IBCP-CNRS, Lyon, France, and Dr. Martin Espariz, IBR-Conicet, Rosario, Argentina, for the insightful discussion and proofreading of the manuscript. We would also like to acknowledge Ms. Sonja Engelstad for kindly proofreading the manuscript.

Disclosure statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Additional information

Funding

This work was supported by grants from the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT, Argentina, PICT-2017-3536 and PICT-2017-4234); and from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina, PIP2017-11220170100377CO). MMC is a Postdoctoral Fellow of CONICET, DK and GDR are Career researchers of CONICET.