Review Vol. 16, No. 7 487 Eur. J. Clin. Microbiol. Infect. Dis., 1997, 16:487-506 Current Knowledge of Bartonella Species M. Maurin, R. Birtles, D. Raoult* Bartonella species are now considered emerging pathogens. Of the 11 currently recog- nized species, four have been implicated in human disease, although only two have been encountered in Europe. Bartonella quintana infections are now being diagnosed among the urban homeless and deprived, manifesting as trench fever, and Bartonella henselae has been shown to be the causative agent of cat scratch disease. Both species also cause a variety of HIV-associated infections, including bacillary angiomatosis. However, perhaps the most significant presentation of bartonellae infection is culture-negative en- docarditis. The epidemiologies of Bartonella infections are poorly understood; most Bar- tonella henselae infections are probably acquired from infected cats, either directly by contact with a cat or indirectly via fleas. No animal reservoir has been implicated for Bartonella quintana; however, infection can be transmitted via the human body louse. Diagnosis of Bartonella infections can be made using histological or microbiological meth- ods. The demonstration of specific antibodies may be useful in some instances, although certainly not in all. Cultivation of Bartonella is difficult, as the bacteria are extremely fas- tidious. Polymerase chain reaction-based or immunological methods for the detection of bartonellae in infected tissues have proven useful. Clinical relapse is often associat- ed with Bartonella infections despite a wide range of prescribed regimens. Only amino- glycosides display in vitro bactericidal activity against intracellular Bartonella species; therefore, they are recommended for treatment of Bartonella infections. Human infections due to Bartonella species are widely considered emerging diseases. They in- clude long-recognized diseases such as Carrion's disease (classic bartonellosis), trench fever, and cat-scratch disease and newer clinical manifesta- tions such as bacillary angiomatosis, peliosis hep- atitis, septicemia, endocarditis, chronic lymphad- enopathy, and neurologic disorders. New molecu- lar biology techniques, mainly based on 16S rRNA gene amplification and analysis, have al- lowed recognition of the role of Bartonella (for- merly Rochalimaea species in a number of these pathological conditions. The association of Barto- nella henselae infection with bacillary angiomato- sis is an example. The availability of specific techniques to diagnose Bartonella infections has led to the description of new Bartonella species and recognition of a broad- ened disease spectrum due to these microorgan- Unit6 des Rickettsies,CNRSUPRESA 6020, Universit6de la Mdditerran6e, Facult6 de M6decine, 27 BoulevardJean Mou- lin, 13385Marseille Cedex5, France. isms.The most striking pathological feature of Bar- tonella infection is the apparent ability of these bacteria to produce angioproliferative lesions in immunocompromised patients, such as those in- fected with HIV. Capillary and endothelial cell proliferations are characteristic histologic findings of bacillary angiomatosis, peliosis hepatitis, and clas- sic bartonellosis. Bartonellae are the only known bacteria with the ability to produce angiogenic tu- mors in humans, although Agrobacterium species, which belong to the same phylogenic group as Bartonella species, produce tumors in plants. The present review focuses on the epidemiologi- cal and clinical aspects of infection due to the Bar- tonella species presently recognized as human pathogens: Bartonella bacilliformis, Bartonella quintana, Bartonella henselae, and Bartonella eli- zabethae. History of Bartonella Before recent taxonomic proposals, Bartonella bacilliformis was the only member of the genus