Overview of Bartonella Infections (Bartonellosis) By Larry M Bush, MD, FACP, Charles E Schmidt College of Medicine, Florida Atlantic University; Maria T Vazquez-Pertejo, MD, FACP, Wellington Regional Medical Center Reviewed / Revised Apr 2022 | Modified Sep 2022 View Patient Education Topic Resources Some Bartonella Infections Bartonella species are gram-negative bacteria previously classified as Rickettsiae.