Nontuberculous mycobacteria (NTM) are emerging as important pathogens in cystic fibrosis lung disease worldwide with an estimated prevalence of about 9%. Mycobacterium avium complex and Mycobacterium abscessus complex include the NTM species most commonly identified in CF. NTM are ubiquitous in the environment and their therapeutic treatment is particularly difficult. Moreover, unsuccessful M. abscessus eradication is considered by the most centers a contraindication for lung transplantation. New and more active drugs are urgently needed, in particular against the most virulent M. abscessus. In this project, taking advantage of researchers’ experience in tuberculosis research, and relying on their collaboration with the Bakh Institute of Biochemistry (Russian Academy of Science) in Moscow, excellent in the field of development of anti-TB drugs, the following goals will be pursued: screening of a library of 500 compounds already synthesized, and other to be synthetized, against M. abscessus growth; evaluation of the sensitivity of other NTM species and clinical isolates to the selected compounds; preliminary characterization of the mechanism of action/resistance of the selected compounds. The final aim is to identify new anti-NMT drugs to be tested in vivo.