Diagnosis of Bartonella henselae Prosthetic Valve Endocarditis in Man, France

To the Editor: Bartonella spp. cause 2% of cases of blood culture– negative endocarditis (1). Early diagnosis of Bartonella spp. infectious endocarditis, is challenging, especially for patients with preexisting valvular heart disease. A diagnosis for these patients requires bacterial culture, serologic testing, or molecular detection in serum or tissue (2). The sensitivity and specificity of Duke modified criteria (3) for detecting endocardial involvement by echocardiography are not optimal, which results in decreased diagnostic accuracy (4). 18Fluorodeoxyglucose–positron emission tomography/computed tomography (18FDG-PET/CT), has been shown to be beneficial for diagnosis (4) and management of prosthetic valve endocarditis (5), particularly if echocardiographic findings are inconclusive (6). This procedure can be performed in patients of all ages by adjusting the dose of 18FDG to the weight of the patient. We report a case that illustrates the usefulness of 18FDG-PET/CT for diagnosis of Bartonella henselae infectious endocarditis in a patient with a prosthetic valve. On October 18, 2012, a 56-yearold man was admitted to Timone Hospital (Marseille, France) with fatigue and weight loss (–6 kg) over the past 6 months. He had had an aortic valve replacement and a bioprosthesis was inserted in 2005 for rheumatic disease. The patient had owned a kitten for 6 months. Laboratory findings showed moderate anemia (hemoglobin level 114 g/L), an elevated C-reactive protein level (34.5 mg/L), and polyclonal hypergammaglobulinemia. A test result was negative for rheumatoid factor. Transthoracic and transesophageal echocardiograms showed a thickened and partial aortic stenosis around the bioprosthesis. Because infectious endocarditis was suspected, treatment with intravenous antimicrobial drugs (amoxicillin, 200 mg/kg/day for 6 weeks and gentamicin, 160 mg/day for 2 weeks) was initiated. On day 7, he was transferred to the cardiology department of Timone Hospital in Marseille, France. An endocarditis test was performed by using an endocarditis kit as described (7). Three routine blood cultures were negative. The patient was given a diagnosis of possible infectious endocarditis by using the Duke score (3). An 18FDG-PET/CT scan was performed and showed 18FDG uptake in the aortic bioprosthesis area (Figure). Results of a whole body scan were normal. An immunofluorescence test for Bartonella spp. showed titers of 400 for IgG against B. quintana and B. henselae (1), and Western blot confirmed a reactivity pattern pathognomonic for B. henselae endocarditis. Results of a PCR performed with a blood sample stored in EDTA (1) were positive for B. henselae. On day 13, antimicrobial drug therapy was