Quinolones are synthetic bactericidal antibiotics that are broad-spectrum. Quinolones are one of the most commonly prescribed classes of antibacterials in the world and are used to treat a variety of bacterial infections in humans. Because of the wide use (and overuse) of these drugs, the number of quinolone-resistant bacterial strains has been growing steadily since the 1990s. Unlike some of the first antibiotics discovered during the past century, the quinolone class of antimicrobial agents was not isolated from living organisms but, rather, was synthesized by chemists.