Final answer:
Nalidixic acid, a quinolone, inhibits bacterial DNA gyrase and was followed by the development of fluoroquinolones like ciprofloxacin and levofloxacin, which have the same mechanism of action.
Step-by-step explanation:
The antibiotic that inhibits bacterial DNA gyrase is nalidixic acid, which is a member of the quinolone family. Nalidixic acid was discovered as a byproduct during the synthesis of chloroquine and targets the bacterial DNA gyrase enzyme, effectively blocking DNA replication in bacteria. Further chemical modifications have led to the creation of fluoroquinolones, such as ciprofloxacin and levofloxacin, which also inhibit DNA gyrase and are effective against a wide range of bacterial infections.