Bartonella as a cause of blood culture-negative endocarditis. Description of five cases.

There is evidence that Bartonella is an etiologic factor in human endocarditis. The objective of this article was to describe cases of endocarditis due to Bartonella observed at a tertiary-care hospital during 1995-2006. Overall, 140 cases of infective endocarditis were seen, of which 10 were blood culture-negative endocarditis, with five being due to Bartonella. In four cases, there had been contact with cats. Only two patients had pre-existing cardiac valvular disease. Three had extracardiac disease manifestations. In three cases, polymerase chain reaction (PCR) tests on cardiac valvular tissue gave positive results. Two patients had positive serology test results for Chlamydophila and another two, positive results for Coxiella burnetii. All five patients needed surgery, and the outcome was favorable in all five. The presence of Bartonella must be considered in patients with blood culture-negative endocarditis. Although serological testing is essential for the diagnosis, cross-reactions between Bartonella and C. burnetii or Chlamydophila are frequent, and PCR tests on cardiac valvular tissue, therefore, play an important diagnostic role.