Bartonellaceae

Bartonellaceae is a family of Gram-negative, non-spore-forming bacteria within the order Rhizobiales of the Alphaproteobacteria. The best-known genus is Bartonella, but the family includes several related genera. Members are typically small, pleomorphic coccobacilli that are fastidious and slow-growing, often requiring enriched media or host cells for culture. Many Bartonellaceae are facultative intracellular parasites that can infect erythrocytes and endothelial cells in mammals, with complex host–pathogen interactions.

Pathogens in this family are primarily transmitted by arthropod vectors. Transmission routes vary by species; for example, B. henselae is associated with domestic cats and cat fleas, B. quintana with human body lice, and B. bacilliformis with sandflies in Andean regions. Natural reservoirs differ by species, including cats for B. henselae and humans for B. quintana, while others involve insect vectors and mammalian reservoirs.

Clinically, Bartonellaceae members can cause a spectrum of disease in humans. B. henselae causes cat scratch disease, typically presenting with localized lymphadenopathy after a scratch or bite. B. quintana causes trench fever, and B. bacilliformis causes Oroya fever and verruga peruana in highland South America. In immunocompromised patients, Bartonella can cause bacillary angiomatosis and endocarditis; bacteremia may be relapsing and chronic.

Diagnosis relies on molecular methods (PCR) and serology; culture is slow and difficult, often requiring specialized media such as BAPGM. Treatment usually includes doxycycline or macrolides (e.g., azithromycin), with longer courses for endocarditis or severe disease.