Bartonella Species, an Emerging Cause of Blood-Culture-Negative Endocarditis.

Since the reclassification of the genus in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different species. The limitations of laboratory tests resulting in this underdiagnosis of endocarditis are discussed. The varied clinical picture of infection and a review of clinical aspects of endocarditis caused by are presented. We also summarize the current knowledge of the molecular basis of pathogenesis, focusing on surface adhesins in the two species that most commonly cause endocarditis, and . We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during -mediated endocarditis and represents a potential reservoir for persistence by these bacteria.