Characterization of Two New Multidrug-Resistant Strains of Mycobacterium smegmatis: Tools for Routine In Vitro Screening of Novel Anti-Mycobacterial Agents

Abstract

Mycobacterium tuberculosis is a pathogen of global public health concern. This threat is exacerbated by the emergence of multidrug-resistant and extremely-drug-resistant strains of the pathogen. We have obtained two distinct clones of multidrug-resistant Mycobacterium smegmatis after gradual exposure of Mycobacterium smegmatis mc2 155 to increasing concentrations of erythromycin. The resulting resistant strains of Mycobacterium smegmatis exhibited robust viability in the presence of high concentrations of erythromycin and were found to be resistant to a wide range of other antimicrobials. They also displayed a unique growth phenotype in comparison to the parental drug-susceptible Mycobacterium smegmatis mc2 155, and a distinct colony morphology in the presence of cholesterol. We propose that these two multidrug-resistant clones of Mycobacterium smegmatis could be used as model organisms at the inceptive phase of routine in vitro screening of novel antimicrobial agents targeted against multidrug-resistant Mycobacterial tuberculosis.

In vitro antimycobacterial activity of medicinal plants Lantana camara, Cryptolepis sanguinolenta, and Zanthoxylum leprieurii

“…We suggest that the lower activity against M. smegmatis results from the fact that it was grown under a rich-nutrient culture medium. However, the fact that mc 2 155 is susceptible to methanolic extracts of the above-mentioned medicinal plants indicates that it can be used as a surrogate for H37Rv for further investigations on in vivo efficacy, safety, and mechanisms of action [18] , [23] . The use of M. smegmatis mc 2 155 is advantageous as it grows fast and can be handled easily.…”

“…In the current study, the antimycobacterial activity of leaves of Lantana camara ( L. camara ), roots of Cryptolepis sanguinolenta ( C. sanguinolenta ), and stem barks of Zanthoxylum leprieurii ( Z. leprieurii ) were tested against (i) a standard laboratory-adapted virulent strain [20] or pan-sensitive M. tb (ATCC 27294/H37Rv) [21] ; (ii) a model for multi-drug resistant (MDR) M. tb strain, a rifampicin-resistant (ATCC 35838/TMC-331) [22] , and (iii) an avirulent surrogate organism of M. tb , M. smegmatis (a nontuberculous mucobacterium, NTM) (ATCC 19420 TM / mc 2 155) [18] , [23] using resazurin microtiter assay (REMA) [24] . Additionally, preliminary qualitative phytochemical tests were conducted.…”

Screening of Compounds for Anti-tuberculosis Activity, and in vitro and in vivo Evaluation of Potential Candidates

“…Therapy with these antibiotics must be taken for 6 months to 2 years, which can result in the emergence of drug resistance and poor therapeutic outcomes ( Adams et al, 2011 ; Akos et al, 2015 ; Castro et al, 2020 ). With the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains ( Tao et al, 2017 ; Arthur et al, 2019 ), tackling the disease using currently available therapeutic regimens is a huge challenge ( Koul et al, 2011 ; Huynh and Marais, 2019 ; Fuad et al, 2020 ). Therefore, there is a desperate need for novel, effective anti-TB drugs that can render the bacteria more susceptible to treatment.…”

Antimicrobial and Efflux Pump Inhibitory Activity of Carvotacetones from Sphaeranthus africanus Against Mycobacteria

“…A distinctive feature of mycobacteria is their highly hydrophobic cell envelope, which presents a substantial permeability barrier rendering the bacteria resistant to many approved antibiotic classes [14]. Mycobacterium smegmatis, Mycobacterium aurum, and Mycobacterium bovis BCG represent useful surrogate models for tuberculosis-causing Mycobacterium tuberculosis and are therefore used in order to analyze efflux pump-mediated resistance, as well as for the in vitro screening of novel antimicrobial compounds [15]. Indeed, the anti-tubercular diarylquinoline drug candidate TMC207 was initially identified using M. smegmatis as a model organism [16].…”