Use of a compound for the manufacture of a medicament for the treatment of a bacterial infection provided that the bacterial infection is other than a Mycobacterial infection, said compound being a compound of Formula (Ia) or (Ib) a pharmaceutically acceptable acid or base addition salt thereof, a quaternary amine thereof, a stereochemically isomeric form thereof, a tautomeric form thereof or a N-oxide form thereof, wherein R1 is hydrogen, halo, haloalkyl, cyano, hydroxy, Ar, Het, alkyl, alkyloxy, alkylthio, alkyloxyalkyl, alkylthioalkyl, Ar-alkyl or di(Ar)alkyl; p is 1, 2 or 3; R2 is hydrogen; alkyl; hydroxy; mercapto; optionally substituted alkyloxy; alkyloxyalkyloxy; alkylthio; mono or di(alkyl)amino wherein alkyl may optionally be substituted; Ar; Het or a radical of formula R3 is alkyl, Ar, Ar-alkyl, Het or Het-alkyl; q is zero, 1, 2, 3 or 4; X is a direct bond or CH2; R4 and R5 each independently are hydrogen, alkyl or benzyl; or R4 and R5 may be taken together including the N to which they are attached; R6 is hydrogen or a radical of formula R7 is hydrogen, alkyl, Ar or Het; R8 is hydrogen or alkyl; R9 is oxo; or R8 and R9 together form the radical —CH═CH—N═;