Molecular Mechanisms of Intrinsic Streptomycin Resistance in Mycobacterium abscessus

Abstract

Streptomycin, the first drug used for the treatment of tuberculosis, shows limited activity against the highly resistant pathogen We recently identified two aminoglycoside-acetylating genes [ and ] which, however, do not affect susceptibility to streptomycin. This suggests the existence of a discrete mechanism of streptomycin resistance. BLASTP analysis identified MAB_2385 as a close homologue of the 3″--phosphotransferase [APH(3″)] from the opportunistic pathogen as a putative streptomycin resistance determinant. Heterologous expression of in increased the streptomycin MIC, while the gene deletion mutant ΔMAB_2385 showed increased streptomycin susceptibility. The MICs of other aminoglycosides were not altered in ΔMAB_2385. This demonstrates that encodes a specific and prime innate streptomycin resistance determinant in We further explored the feasibility of applying-based streptomycin counterselection to generate gene deletion mutants in Spontaneous streptomycin-resistant mutants of ΔMAB_2385 were selected, and we demonstrated that the wild-type is dominant over the mutated in merodiploid strains. In a proof of concept study, we exploited this phenotype for construction of a targeted deletion mutant, thereby establishing an -based counterselection method in.

Increased drug permeability of a stiffened mycobacterial outer membrane in cells lacking MFS transporter Rv1410 and lipoprotein LprG

“…Novobiocin and vancomycin were dissolved in water, rifabutin and clofazimine in DMSO, tetracycline in ethanol and ofloxacin in a 0.1 M HCl solution. The MICs for M. abscessus and M. smegmatis were performed in 96‐well plates as previously described (Dal Molin et al , ). The MICs were determined on day 5 for M. smegmatis and M. abscessus .…”

The Role of Antibiotic-Target-Modifying and Antibiotic-Modifying Enzymes in Mycobacterium abscessus Drug Resistance

“…Deletion of MAB_2385 enhanced the susceptibility of M. abscessus towards streptomycin by 16-fold ( Table 1 ). Furthermore, MAB_2385 was able to confer streptomycin resistance when heterologously expressed in M. smegmatis ( Dal Molin et al, 2017 ). To the best of our knowledge other annotated aminoglycoside phosphotransferases (such as MAB_0163c, MAB_0313c, MAB_0327, MAB_0951, and MAB_1020) and aminoglycoside acetyltransferases (for example, MAB_0247c, MAB_0404c, MAB_0745, MAB_4235c, and MAB_4324c) have not been addressed experimentally, however, interesting regulatory features of drug resistance genes have been elucidated.…”

“…Despite the success of β-lactamase inhibitors, the concept of designing drugs which target intrinsic resistance mechanisms in bacteria, has not gained substantial clinical exploitation beyond this antibiotic class ( Brown, 2015 ). Recently, a repertoire of drug-modifying and target-modifying enzymes conferring innate resistance to aminoglycosides, tetracyclines, rifamycins, and macrolides in M. abscessus were delineated ( Nash et al, 2009 ; Dal Molin et al, 2017 ; Rominski et al, 2017a , c ; Rudra et al, 2018 ). Likewise, attempts to identify chemical entities which could potentially rescue the function of one or more key members from each aforementioned antibiotic group, should be pursued in the near future.…”

Repositioning rifamycins for Mycobacterium abscessus lung disease

“…All NTM species and particularly M. abscessus are intrinsically resistant to many drug classes [9][10][11][12]. Among the many factors underlying M. abscessus' natural drug resistance, the pathogen's ability to metabolize most antibiotic classes and convert them to inactive derivatives stands as a key mechanism [10,[13][14][15][16][17].…”