Blood cell findings resembling Bartonella spp.

Some Bartonella species are able to invade red blood cells (RBC) and may cause persistent infection in the susceptible host. Use of transmission electron microscopy (TEM) demonstrates, inside erythrocytes, the typical triple-walled agents. However, when examining ultrathin sections of blood cells, the authors have, on several occasions, detected intraerythrocytic abnormalities that mimic but are not typical of Bartonella spp. Small endovesicles, pseudoinclusions, cavities, and irregular hemoglobin granules distribution, resulting in regions of increased or decreased electron density, may be observed in the erythrocytes and platelets, which may be confused with bartonellas. So far, detailed ultrastructural findings of Bartonella spp. in blood cells have not yet been described. Aiming to improve TEM interpretation of blood cells changes, in routine examination of blood sections of patients with suspected bartonellosis, the authors studied the morphological findings they have observed, and present their putative nature, according to information in the literature.