Use of a compound for the manufacture of a medicament for the treatment of a bacterialinfection provided that the bacterial infection is other than a Mycobacterialinfection, said compound being a compound of formula (Ia) or (Ib) a pharmaceuticallyacceptable acid or base addition salt thereof, a stereochemically isomericform thereof, a tautomeric form thereof or a N-oxide form thereof. Several ofthese compounds are also claimed as such. Further the combination of the abovecompounds with other antibacterial agents is described