Human endocarditis on prosthetic valves due to Bartonella vinsonii subsp. berkhoffii

Bartonella spp. infections are increasingly recognized as causes of zoonotic diseases. One of the most severe infections caused by Bartonella spp. is infective endocarditis, predominantly affecting individuals with underlying valvular heart disease, immunosuppression, and homelessness. The microbiological diagnosis of these endocarditis cases is highly challenging due to the fastidious nature of Bartonella spp., requiring specialized serologic and molecular tests in addition to blood cultures, which are usually negative. While Bartonella henselae and Bartonella quintana are the main species associated with these infections, other rarer Bartonella species are increasingly being identified in such cases. Herein, we report the first case of infective endocarditis on prosthetic heart valves caused by Bartonella vinsonii subsp. berkhoffii in a 74-year-old shepherd, also being the fourth reported human endocarditis case due to this pathogen. This Bartonella subspecies has been associated with canid exposure, as these animals are believed to be its main reservoir. Interestingly, in our case the bacteria grew in heart-valve culture, allowing for species identification by whole-genome sequencing. Our patient, whose risk factors included canid exposure, cardiac anomalies, and immunosuppression, is a clear example of the importance of considering this pathogen in such high-risk populations.