MRCP2-0313
A 68-year-old with a history of ischaemic heart disease (primary percutaneous intervention for a STEMI four years ago) is admitted with a pyrexia of unknown origin. During examination, a systolic murmur is noted, but chest auscultation is unremarkable. His pulse is 96/min, temperature 38.2ºC, and blood pressure 104/66 mmHg. Three years ago, his post-myocardial infarction echocardiogram showed no valvular disease. However, a petechial rash is noted on his hands and legs, and urine dipstick shows blood ++. The presumptive diagnosis is infective endocarditis, and he is given empirical treatment with IV amoxicillin and gentamicin. Two days later, blood cultures reveal a coagulase-negative staphylococcus. What is the most appropriate course of action regarding antibiotic therapy?