Bartonella, a common cause of endocarditis: a report on 106 cases and review

Abstract

Bartonella spp. are fastidious bacteria that cause blood culture-negative endocarditis and have been increasingly reported. In this study, we included all patients retrospectively and prospectively diagnosed with Bartonella endocarditis in our French reference center between 2005 and 2013. Our diagnosis was based on the modified Duke criteria and microbiological findings, including serological and PCR results. To review the published literature, we searched all human Bartonella endocarditis cases published in the PubMed database between January 2005 and October 2013. We report here a large series of 106 cases, which include 59 cases that had not previously been reported or mentioned. Indirect immunofluorescence assays, Western blotting, and real-time PCR from total blood, serum, and valve tissue exhibited sensitivities of 58%, 100%, 33%, 36%, and 91%, respectively. The number of cases reported in the literature between 2005 and 2013 increased to reach a cumulative number of 196 cases. The number of cases reported in the literature by other centers is increasing more rapidly than that reported by our French reference center (P < 10(-2)). Currently, there is a lack of criteria for the diagnosis of Bartonella endocarditis. We suggest that a positive PCR result from a cardiac valve or blood specimen, an IgG titer of ≥800 using an immunofluorescence assay, or a positive Western blot assay be considered major Duke criteria for Bartonella endocarditis. There is no real increase in the incidence of these infections but rather a better understanding and interest in the disease resulting from the improvement of diagnostic tools.

FIG 1

(A) Western immunoblotting of serum from a patient with B. quintana endocarditis presenting with negative serology and a positive PCR for the cardiac valve. The utilized antigens included B. quintana (lanes 1), B. henselae strain Houston (lanes 2), B. elizabethae (lanes 3), B. vinsonii subsp. berkhoffii (lanes 4), and B. alsatica (lanes 5). (B) B. quintana adsorbed sera. (C) B. henselae adsorbed sera. This Western blot presents a typical profile observed for Bartonella-induced endocarditis cases. Molecular masses (in kilodaltons) are given on the left.

FIG 2

Number of cases of endocarditis induced by Bartonella spp. between January 2005 and October 2013 diagnosed in our center and number of cases reported in the published literature by other centers. A cumulative frequency curve of the total cases of endocarditis induced by Bartonella spp. was generated. Chi-square test for trends: P < 10⁻².