Antibiotic Resistance Characteristics of $\textit{Mycobacterium}$ $\textit{Abscessus}$ Rely on Specific Outer Membrane Porins and Surface-Associated Glycopeptidolipids

“Mycobacterium abscessus is an opportunistic pathogen, ubiquitous in the environment, that often causes infections in humans with compromised natural defences such as patients with cystic fibrosis or other chronic lung diseases. A current taxonomic classification suggests separation of M. abscessus into three distinct subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. bolletii, and M. abscessus subsp. massiliense. Although a saprophyte in water and soil, following lung infection M. abscessus can swiftly grow and survive intra-cellularly within macrophages as well as in extra-cellular caseous lesions and airway mucus. Several factors contribute to the success of this rapidly growing mycobacterium. A plethora of intrinsic resistance mechanisms renders almost all clinically used antibiotics ineffective against M. abscessus. In addition, the presence of a highly dynamic open pan-genome in M. abscessus might explain the ease with which the bacterium evolves and adapts to a wide-spectrum of stressful environmental conditions encountered in diverse habitats. Importantly, the respiratory habitat of M. abscessus brings it in close proximity to highly virulent pathogens (for example, Pseudomonas aeruginosa in cystic fibrosis lung) which can serve as donors of novel drug resistance or virulence genes” (Luthra, S. et al.). “Mechanisms underpinning intrinsic drug resistance of M. abscessus are multi-fold and fall into two main groups: first, the presence of a highly impermeable cell envelope and/or multi-drug efflux pumps might reduce the effective concentration of antibiotics within the bacterial cells; second, the genome of M. abscessus encodes several putative enzymes which can inactivate antibiotics by modification and/or degradation or lower the affinity of the drug for its target by modifying the target. For long, molecular investigations aimed at elucidating antibiotic resistance mechanisms of M. abscessus were limited, however, significant progress has been made in recent years owing to the development of ...