Nitroxoline: a potent antimicrobial agent against multidrug resistant Enterobacteriaceae.

Antimicrobial resistance has become a prime global concern. An ability of the microbes to produce enzymes to destroy antimicrobial drugs is one of the well-known mechanisms underlying the resistance. 8-Hydroxyquinoline (8HQ) and derivatives were reported to exert diverse biological effects such as antimicrobial, antioxidant and antineurodegenerative activities. Herein, 8HQ (1), nitroxoline (NQ, 2) and 7-Br-8HQ (3) were investigated for antimicrobial activity against including extended spectrum β-lactamase (ESBL)-producing and carbapenemase-producing strains as well as the effect of metal ions. These compounds (1-3) displayed the great antimicrobial activity against fifty-eight bacterial isolates of and , in which NQ (2) exerted the highest antimicrobial activity with a MIC of 42.04 μM (8 µg/mL) and MBC of 168.28 μM (32 µg/mL). The MIC values of NQ (2) and 7-Br-8HQ (3) were significantly increased in the presence of Cu and Fe. This finding reveals that NQ could be an effective compound to be further developed as an antimicrobial agent for combating infections.