Prosthetic Valve Endocarditis with Bartonella washoensis in a Human European Patient and its Detection in Red Squirrels (Sciurus vulgaris)

Members of the genus Bartonella are fastidious Gram-negative facultative intracellular bacteria that are typically transmitted by arthropod vectors. Several Bartonella spp. have been found to cause culture-negative endocarditis in humans. Here, we report the case of a 75-year old German woman with prosthetic valve endocarditis due to Bartonella washoensis. The infecting agent was characterized by sequencing of six housekeeping genes (16S rRNA, ftsZ, gltA, groEL, ribC, rpoB) applying a multilocus sequence typing (MLST) approach. The 5097 bp of the concatenated housekeeping gene sequence from the patient were 99.0% identical to a B. washoensis strain from a red squirrel (Sciurus vulgaris orientis) from China. 39% (24/62) of red squirrel (S. vulgaris) samples from the Netherlands were positive for the B. washoensis gltA gene variant detected in the patient. This suggests that the red squirrel is the reservoir host for human infection in Europe.