Mycotic aneurysms: a case report, clinical review and novel imaging strategy

Abstract

A 62-year-old man presented to a district general hospital with a 4-week history of fever, drenching sweats, lethargy and intermittent thoracic back pain. Two weeks prior to onset, a pacemaker had been inserted for recurrent syncope secondary to carotid sinus hypersensitivity. His other past medical history included a permanent tracheostomy following resection of a laryngeal carcinoma 8 years previously, and ischaemic heart disease. The latter culminated in an acute coronary syndrome 7 months before the current presentation, for which primary angioplasty was undertaken with insertion of six drug-eluting coronary artery stents requiring dual antiplatelet therapy for at least 1 year. On admission , he was febrile at 38.5°C. There were no peripheral stigmata of infective endocarditis, auscultation of the pre-cordium identified no murmurs and the pacemaker site was not inflamed. Systemic examination was otherwise unremarkable, as were chest radiography and urinalysis. Transthoracic echocardiography demonstrated good systolic function, with no valvular regurgitation or pacemaker lead vegetations. In the absence of a clear septic focus, he was commenced on piperacillin–tazobactam. Blood tests showed haemoglobin of 11.6 g/dl, white cell count of 5.7 × 109 cells/l and platelet count of 52 × 109 cells/l. C-reactive protein (CRP) was elevated at 272 mg/l. Coagulation screen was normal. Multiple blood cultures were drawn, which grew methicillin-sensitive Staphylococcus aureus . Intravenous flucloxacillin and rifampicin were commenced. He was consequently transferred to the London Heart Hospital for further management. The pacemaker was explanted and there was marked clinical improvement. Nonetheless, despite antibiotic therapy he continued to have high-grade pyrexias, without diurnal variation, and elevated serum CRP concentrations. An extensive septic screen, including urine and blood cultures, chest radiographs and repeated transthoracic and transoesophageal echocardiograms revealed no abnormalities. Computed tomography (CT) scan of the thorax, abdomen and pelvis to identify any occult septic focus revealed a large infrarenal aortic aneurysm, as well …