Fluoroquinolones and Quinolones
These drugs are a newer type of anti-infective. Their action is to interfere with DNA replication by inhibiting an enzyme complex called DNA gyrase. This can also affect mammalian cell replication. Their chemical structure is of a quinolone base with a fluorine side chain. Quinine is also a quinolone, but it does not have clinically useful antibacterial properties. Nalidixic acid is a quinolone without a fluoride side chain. Development of resistance to these drugs has been suprisingly high.