Case Studies

Case 4: A young man with a new murmur

You are the house officer on a diabetes and endocrine firm. One of your patients is a 34-year-old man, Mr RJ, who was admitted with fever and a rash. On examination, he had a blanching maculopapular rash on the arms, buttocks and lower abdomen, which was itchy. His chest was clear. In view of his fever, you take blood cultures. Four days later the microbiology registrar bleeps you to inform you that the blood cultures have grown Gram-positive cocci. She advises you to start the patient on high dose intravenous flucloxacillin. Each day on the ward round, your SHO examines the patient’s chest and notes that it is clear, his heart sounds are normal and that there are no added sounds. The next morning your team agrees to split the ward round and you ex-amine Mr RJ. You note a new early diastolic murmur that is high in pitch. Your own registrar is concerned at this development and requests that you arrange a transthoracic echocardiogram (TEE). The echo reports thickening of the aortic valve and the presence of a moderate to severe jet of aortic regurgitation. Additionally, a small ventricular septal defect was noted. Your registrar then requests that you arrange an urgent transoesophageal echocardiogram (TOE). The TOE revealed that the patient had an aortic root abscess.

• 1.What does ‘Gram-positive’ mean?

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  Gram-positive means that bacteria have stained dark blue on Gram’s staining – they retain the stain owing to the high amount of peptidoglycan in their cell walls. In contrast, Gram-negative organisms have a much thinner peptidoglycan cell wall and therefore do not stain dark blue.

• 2.Which organism has most likely been isolated on blood cultures?

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  The organism that has been isolated on blood cultures is Staphylococcus aureus, a Gram-positive coccus which is the primary pathogen of infective endocarditis.

• 3.What is your diagnosis?

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  This man has infective endocarditis, which is an infection of the endocardial surface of the heart that may include one or more heart valves. A fever and a new murmur is infective endocarditis until proven otherwise. Infective endocarditis is extremely serious – the infected heart valves can fail leading to cardiac failure and infected emboli can damage other organs.

• 4.How do you further manage Mr RJ?

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  Mr RJ must continue his course of high dose intravenous antibiotics. In view of his aortic root abscess, Mr RJ required an aortic valve replacement. Repair of his ventricular septal defect was also undertaken.

• 5.What is a ventricular septal defect?

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  A ventricular septal defect (VSD) is a hole in the septum that separates the ventricles of the heart, resulting in commu-nication between the ventricles with the result that blood flows from the LV to the RV (left-to-right shunt). A significant VSD can be diagnosed clinically by auscultation of a harsh pansystolic murmur at the left sternal border. The conse-quence of a left-to-right shunt is that, over time, the pressure in the pulmonary circulation increases and pulmonary hypertension develops.