Final answer:
Levofloxacin (Levaquin®) is used to treat bacterial infections, particularly of the respiratory tract. Despite its efficacy, it can have serious side effects and may become ineffective against resistant strains of bacteria, possibly indicated by the symptoms David is experiencing.
Step-by-step explanation:
Levofloxacin (Levaquin®) is a fluoroquinolone antibiotic primarily used to treat bacterial infections of the respiratory tract such as pneumonia and bronchitis. It belongs to a class of drugs known for binding affinity with bacterial DNA gyrase, which is crucial for DNA replication, thereby inhibiting the growth and proliferation of bacteria. While effective against a broad spectrum of gram-positive and gram-negative bacteria, its usage can lead to side effects such as neurotoxicity, phototoxicity, and an increased risk of tendon rupture.
David's additional symptoms of headaches, a stiff neck, difficulty focusing, and the development of a rash suggests that he could be experiencing side effects from the medication or a different type of infection. Infections consistent with his symptoms, which might be treated with levofloxacin, include respiratory infections and possibly bacterial meningitis, indicated by the stiff neck and headaches. However, the ineffectiveness of the antibiotic along with the new symptoms might also highlight an emerging drug-resistant strain of bacteria or an incorrect initial diagnosis.