Quinolones

Fluoroquinolones are synthetic antibacterial agents that inhibit bacterial DNA replication by targeting two essential enzymes, DNA gyrase and topoisomerase IV. They have broad spectra of activity against both gram-negative and gram-positive bacteria. Available in oral and intravenous formulations, they have been used widely to treat infections at many different body sites, including the urinary tract, respiratory tract, abdomen, bones, joints, and skin and skin structures. Resistance has emerged to different degrees with clinical use and is due to either mutations that alter the target enzymes or cause increased expression of efflux pumps that remove drug from the bacterial cell or, in gram-negative bacteria, to acquired genes on plasmids that encode target protection proteins, drug-modifying enzymes, or efflux pumps. These plasmid-encoded genes are often linked to other plasmid genes encoding resistance to other antimicrobials. Fluoroquinolones are generally well tolerated but have been associated with tendon disorders. Some members of the class have also been associated with prolongation of the QT interval and arrhythmia, dysglycemia, hepatotoxicity, seizures, and peripheral neuropathy.