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

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 after gradual exposure of mc² 155 to increasing concentrations of erythromycin. The resulting resistant strains of 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 mc² 155, and a distinct colony morphology in the presence of cholesterol. We propose that these two multidrug-resistant clones of could be used as model organisms at the inceptive phase of routine in vitro screening of novel antimicrobial agents targeted against multidrug-resistant .