The present invention relates to novel substituted quinoline derivatives according to the general Formula (Ia) or Formula (Ib): the pharmaceutically acceptable acid or base addition salts thereof, the quaternary amines thereof, the stereochemically isomeric forms thereof, the tautomeric forms thereof and the N-oxide forms thereof. The claimed compounds are useful for the treatment of a bacterial disease including a mycobacterial disease, particularly those diseases caused by pathogenic mycobacteria such as Mycobacterium tuberculosis, M. bovis, M. avium and M. marinum. Also claimed is a composition comprising a pharmaceutically acceptable carrier and, as active ingredient, a therapeutically effective amount of the claimed compounds, the use of the claimed compounds or compositions for the manufacture of a medicament for the treatment of bacterial diseases and a process for preparing the claimed compounds.