George Lesher discovered nalidixic acid, the first of the quinolone antibiotics, in 1962 when he and coworkers were attempting to synthesize the anti-malaria drug chloroquine. Due to various factors, nalidixic acid was soon found to only exhibit activity against gram-negative bacteria inhabiting the human urinary tract. Available in liquid and caplet form for oral consumption, the drug works by interfering with the DNA of bacteria, effectively preventing the microorganisms from reproducing and causing them to eventually die out. In addition, the compound is important as the forerunner of all members of the family of topoisomerase inhibitors, many of the more recently developed of which exhibit a broad spectrum of activity.