a 27-y/o male with a history of iv drug abuse presents with fever, chills, cough, hemoptysis, and dyspnea. physical exam reveals t 101.5 f, tachycardia, and tachypnea. cardiac exam reveals a gr. 3/6-holosystolic murmur which increases with inspiration heard best at the 5th intercostal space left of the sternum. there were no signs of peripheral embolization. chest x-ray reveals several small cavitary lesions without pulmonary vascular congestion. his most likely diagnosis is