Mycogenic Metal Nanoparticles for the Treatment of Mycobacterioses.

Marta Filipa Simões,André Antunes,Cristiane Angélica Ottoni

doi:10.3390/antibiotics9090569

Abstract

Mycobacterial infections are a resurgent and increasingly relevant problem. Within these, tuberculosis (TB) is particularly worrying as it is one of the top ten causes of death in the world and is the infectious disease that causes the highest number of deaths. A further concern is the on-going emergence of antimicrobial resistance, which seriously limits treatment. The COVID-19 pandemic has worsened current circumstances and future infections will be more incident. It is urgent to plan, draw solutions, and act to mitigate these issues, namely by exploring new approaches. The aims of this review are to showcase the extensive research and application of silver nanoparticles (AgNPs) and other metal nanoparticles (MNPs) as antimicrobial agents. We highlight the advantages of mycogenic synthesis, and report on their underexplored potential as agents in the fight against all mycobacterioses (non-tuberculous mycobacterial infections as well as TB). We propose further exploration of this field.

Highlights

There are almost 200 described species of the ubiquitous acid-fast bacteria of the genus Mycobacterium [1]
NP-based systems are able to circumvent many of the challenges related to mycobacterial infections since they can target the infected cells and act directly on the cell wall of intracellular pathogens, as is the case of Mycobacterium tuberculosis (MTb) when it infects macrophages in pulmonary TB [26]
The mechanisms that have been reported to explain the effects of metal nanoparticles (MNPs) on microbial cells include: DNA damage, protein damage, mitochondrial damage, attachment to 30S ribosome subunit, oxidation of cellular components, release of metal ions, damage to the proton efflux pump, disruption, or prevention of biofilm formation, disruption of cell membrane, disruption of transmembranar electron transport, and production of reactive oxygen species (ROS) [17,49]

Summary

Introduction

There are almost 200 described species of the ubiquitous acid-fast bacteria of the genus Mycobacterium [1]. The distinction between pathogenic and non-pathogenic species is not always trivial as many of them share the same phenotypic and genotypic characteristics and have very limited differences [3,5]. Despite their similarities, NTM have lower human pathogenicity than mycobacteria from the Mycobacterium tuberculosis (MTb) complex [6,7] (species with 85–100% DNA homology with MTb, which include M. africanum, M. bovis, M. caprae, M. canetti, M. pinnipedii, M. tuberculosis, M. microti, or M. mungi, which are all pathogenic [3,7,8]). The fact that NTM share many infectious traits with the causing agents of tuberculosis (TB) allows them to be used in many research studies as model organisms of infection for this disease, with the advantage of being less pathogenic and faster growing species [7,9]

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Conclusion