A 68-year-old man presents to the emergency department with a 4-day history of cough productive of rust-colored sputum. He is experiencing dyspnea, fever with chills, and sharp left-sided chest pain during inspiration and with coughing. Past medical history is significant for hypertension, peripheral arterial disease, and gout. He smokes 10 cigarettes per day, and he does not drink alcohol. He works part-time as a music teacher and as a janitor, and he lives with his wife and two cats. Vital signs show tachycardia and tachypnea with a normal blood pressure. Physical examination reveals at the left lung base upon auscultation. Cardiac examination reveals tachycardia and normal heart sounds. Abdominal examination is normal. A chest x-ray is ordered. Gram stain of the sputum reveals a gram-positive, lancet-shaped diplococci.

The patient was started on an antibiotic that inhibits peptidoglycan transpeptidase. Which of the following is the most likely antibiotic?

• A) Amoxicillin
• B) Doxycycline
• C) Levofloxacin
• D) Linezolid
• E) Vancomycin