Nontyphoid Salmonella-infected mycotic aneurysm in a patient with rheumatoid arthritis

Abstract

A 60-year-old male presented, and was admitted, to our hospital with a 1-week history of intermittent chills and high fever. He has rheumatoid arthritis for 2 years with regular medication of hydroxychloroquine, methotrexate, sulfasalazine, and low-dose prednisolone (5 mg daily). The patient had a history of type 2 diabetes for which he was under regular medication. General malaise and dyspnea would occur during the episode of fever. On admission to our hospital, his blood pressure was 129/74 mm Hg, and his body temperature was 39 C. His heart sounds were normal with no murmur; the lungs were clear to auscultation. The abdomen was soft without palpable masses or tenderness; the liver and spleen were not palpable. The patient had mild back pain. A complete blood count revealed 9,000 leukocytes/lL and 221,000 platelets/uL, with mild anemia (hemoglobin: 9.4 g/dL). The C-reactive protein (CRP) level was 24.1 mg/dL (normal\0.5 mg/dL) and the erythrocyte sedimentation rate (ESR), 64 mm/h (normal \15 mm/h). Urine analysis and culture yielded negative results. Two blood cultures obtained before intravenous antibiotic administration tested positive for salmonella group D. No vegetations or signs of infective endocarditis were detected on transthoracic echocardiography. Computed tomography (CT) showed a saccular aneurysm arising from the abdominal aorta, with fatty stranding, free air-bubbles (arrow indicates air-bubbles and asterisk indicates aneurysm; Fig. 1) and periaortic fluid accumulation (Fig. 2). Mycotic aneurysm was confirmed. The patient received surgical management for debridement of abscess and intravenous ceftriaxone 2 gm daily continuously for 8 weeks. The patient had an excellent clinical response and was discharged 2 months later with no recurrence of fever. Mycotic aneurysms are uncommon of all aortic aneurysms, and the overall mortality is about 50 % after treatment. The common initial symptoms include pain over abdomen or back, fever, general discomfort, and hypovolaemic shock [1]. The most frequent site of mycotic aneurysms is abdominal aorta, followed by the thoracic and suprarenal abdominal aorta. High level of ESR and CRP can be found from the laboratory data. Abdominal CT can be used for early detection of mycotic aneurysms. Saccular, multilobulate, periaortic soft tissue stranding, and irregular peripheral enhancement of arterial walls can be found from the image study. The cultures from blood or the aneurismal content include Salmonella species, staphylococcus aureus, Streptococcus pneumoniae, and Mycobacterium tuberculosis [1]. Immunocompromised patients including HIV infection, patients with received immunosuppressive agent may develop fulminating bacteremia, which leads to the formation of infected aneurysms [2, 3]. Antimicrobial treatment alone usually results in poor prognosis; therefore, surgery may play a major role in reducing mortality. The combination of antimicrobial treatment and surgical debridement of surrounding necrotic tissue with revascularization is indicated in the patient with mycotic aneurysm. D.-H. Yang (&) Division of Rheumatology/Immunology/Allergy, Department of Internal Medicine, Taichung Armed Forces General Hospital, No 348, Sec. 2, Chung Shan Road, Taiping 411, Taichung, Taiwan, Republic of China e-mail: deng6263@ms71.hinet.net