Use of pyrroloquinoline compounds to kill clinically latent microorganisms

A compound of formula (Ia), or a pharmaceutically-acceptable salt thereof, wherein the compound of formula (Ia) is represented by the structure:

• wherein,
• R1 represents C1-5 alkyl which is optionally substituted by C3-5 cycloalkyl, phenoxy, benzodioxanyl, benzodioxolyl or phenyl, which phenyl group is optionally substituted by one or more substituents selected from halo, methyl and methoxy;
• C3-6 cycloalkyl, which is optionally fused to a benzene ring to provide a benzo-fused cycloalkyl group;
• phenyl, which phenyl group is optionally substituted by one or more substituents selected from halo, C1-4 alkyl, OH, C1-4 alkoxy, which alkoxy group is optionally substituted by N(CH3)2, phenoxy, which phenoxy group is optionally substituted by one or more substituents selected from methoxy, halo, pyridyloxy and piperazinyl, which piperazinyl group is optionally substituted by methyl;
• pyridyl which is optionally substituted by methoxy or phenoxy;
• or
• piperidinyl which is optionally substituted by C1-2 alkyl, which alkyl group is optionally substituted by phenyl;
• R2 represents unsubstituted C1-3 alkyl;
• R3a and R3c independently represent H, C1-4 alkoxy optionally substituted by one or more halo atoms, or phenoxy optionally substituted by one or more substituents selected from halo, methyl and methoxy;
• provided that R3a and R3c do not both represent H;
• and
• Rab and R3″ both represent H.