Afebrile Blood Culture–Negative Endocarditis

• Whipple's disease
• Endocarditis, bacterial
• Tropheryma whippelii
• Heart valve diseases
• Gastrointestinal diseases

Fever, positive blood culture, and the presence of valvular vegetation on echocardiography are the usual indicators of infective endocarditis. If a patient does not have a fever, however, clinicians frequently do not consider this diagnosis. In such cases, diagnosis may be delayed until hemodynamic compromise necessitates valve replacement, as in the case of Coxiella burnetii infective endocarditis (1) and the report by Gubler and colleagues (2) in this issue.

Clinicians usually diagnose infective endocarditis by using the Duke criteria (3), which include two major criteria (blood cultures typical of infective endocarditis and vegetations on findings on echocardiography) and seven minor criteria (positive blood culture, fever, previous heart disease, arterial embolism, positive results on serologic examination for endocarditis bacterial pathogens, immunologic disorders, and atypical but compatible findings on echocardiography).

Gubler and colleagues report on endocarditis caused by Whipple disease bacterium in four middle-aged patients with arthralgia and heart failure. All four patients were afebrile, and none had predominantly digestive involvement. On echocardiography, three of the four patients had vegetations; blood cultures and results of serologic examination performed for endocarditis were negative. Of interest, patients presented with cardiac manifestations rather than obvious symptoms of infectious processes. Before the pathologic examination, one patient fulfilled no Duke criteria, two patients each fulfilled one major Duke criterion, and one patient fulfilled two Duke criteria (one major and one minor). Without examination of the excised valves, the diagnosis of infective endocarditis could not have been confirmed in any patient and no patient could have been considered to have blood culture–negative infective endocarditis. Histologic examination and polymerase chain reaction (PCR) of the excised valves led to the final treatable diagnosis of Whipple disease. The authors concluded …