Final answer:
Fourth-generation quinolones include moxifloxacin and gemifloxacin, which have increased Gram-positive coverage and are used for various infections.
Step-by-step explanation:
Two examples of fourth-generation quinolones include moxifloxacin and gemifloxacin. These fluoroquinolones are synthetic antimicrobial agents with an expanded spectrum of activity, including effectiveness against both Gram-positive and Gram-negative bacteria as well as anaerobic bacteria. The mechanism of action involves the inhibition of bacterial enzymes DNA gyrase and topoisomerase IV, which are essential for DNA replication. Unlike earlier generations, fourth-generation quinolones offer greater coverage against Gram-positive bacteria while retaining the efficacy against Gram-negative pathogens. Due to their enhanced activity, they are often used to treat a variety of infections, ranging from respiratory and urinary tract infections to skin and intra-abdominal infections.