A case of prosthetic valve endocarditis with increased vegetation size despite appropriate antibiotic therapy

Excerpt

A 51-year-old man was referred to our hospital for a hemorrhagic cerebral infarction (Fig. 1 A) and a month-long fever. He had undergone Bentall surgery with an INSIPIRIS 25-mm bioprosthetic valve for localized ascending aortic dissection and severe aortic regurgitation (AR) 4 years previously and was treated for pyelonephritis 2 months previously. Transthoracic echocardiography (TTE) on admission showed left ventricular ejection fraction of 60%, no AR, but a suspected 8 × 10 mm vegetation attached to the aortic prosthetic valve (Fig. 1 B, Videos 1, 2). Transesophageal echocardiography (TEE) confirmed vegetation attached to the aortic prosthetic valve (Fig. 1C, D, Videos 3–5), and blood culture detected Enterobacter cloacae, leading to a diagnosis of prosthetic valve endocarditis (PVE). Fluorodeoxyglucose positron emission tomography/computed tomography scan revealed an accumulation image consistent with the vegetation identified by TEE, with no accumulation in the artificial vascular graft (Fig. 1E). We initiated treatment with intravenous antibiotics (cefepime 4 g/day and tobramycin 4 mg/kg/day). Three weeks after the diagnosis, blood cultures were negative, but TTE revealed that the size of the vegetation had increased, and a new 11 mm mobile string-like structure was noted (Figures. 1F, G, Videos 6, 7). Subsequently, the patient underwent aortic valve replacement with a Regent 21-mm mechanical valve. The removed aortic prosthetic valve showed a vegetation consistent with the echocardiographic findings (Fig. 1H). The pathology showed a vegetation composed of fibrin, platelets, and neutrophils, which destroyed the collagen fibers of the aortic prosthetic valve. However, the culture results of the removed aortic prosthetic valve were negative. He was discharged without any complications after 8 weeks of antibiotic therapy.

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