A 66-year-old man presents with shoness of breath, myalgia, headache along with multiple episodes of fever with rigors. He went to the local doctor who treated him for the flu. However, his symptoms worsened, and by the day of presentation he was complaining of a dry cough and marked shoness of breath and diarrhoea. Patient is a non-smoker. Auscultation of chest reveals bilateral crackles and bronchial breathing in both lower zones posteriorly. Lab findings, Elevated CRP level Hypocalcemia Acidosis and marked hypoxia Gram staining of sputum revealed small, pleomorphic, faint, gram negative bacilli. Chest X-ray What is the drug of choice of the above organism: –