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Institut für Medizinische Mikrobiologie

Drug resistance and virulence mechanisms of Mycobacterium abscessus

Mycobacterium abscessus, an environmental saprophyte, is one of the most pathogenic and drug-resistant organisms among rapidly growing mycobacteria (RGM). It accounts for 80 % of all lung infections due to RGM, particularly exacerbations of chronic lung disease patients with cystic fibrosis. Currently, there is no reliable antibiotic regimen for the treatment of infections with M. abscessus, as this bacterium demonstrates a high level of intrinsic resistance to many commonly administered drugs, including tuberculosis drugs. The high level of intrinsic drug resistance not only restricts treatment options but also application of common genetic tools to elucidate gene functions.

We recently developed tools for genetic manipulation of M. abscessus. We now exploit these tools for elucidating the molecular mechanisms of drug resistance and virulence of this emerging pathogen.

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Rifampicin Etest

Rifampicin susceptibility testing of Mycobacterium abscessus

 

a) M. abscessus wild-type
b) Δarr deletion mutant
c) complemented Δarr deletion mutant

Growth of the wild-type and the complemented mutant up to the edge of the E-Test device indicate a high level of Rifampicin resistance (MIC > 32 mg/L). Upon inoculation of the plate with the Δarr mutant strain a large bacteria free halo is observed, indicating susceptibility to Rifampicin (MIC = 0.5 mg/L). This experiment demonstrates that Arr is the major innate Rifampicin resistance determinant of M. abscessus.