Cat scratch disease and other zoonotic Bartonella infections.

S ince the early 1990s, there have been substantial advances in the understanding of the etiology, reservoir potential, vector transmission, and pathogenesis of bartonellosis in cats, dogs, and humans. Bartonella spp are fastidious, hemotropic, gram-negative organisms that have been recently identified in a wide range of domestic and wild mammals. 1 These organisms are considered to be emerging zoonotic agents. Bartonella spp are usually vector borne, and the vector varies with the Bartonella spp involved (eg, sandflies for B bacilli-formis or human body lice for B quintana; Appendix). Fifty years ago, cat scratch disease was identified in France and described by Debré et al. 2 It is now known that this common zoonosis is caused by a bacterium of the genus Bartonella and not by Afipia felis. 3 Cats are the main reservoir of this bacterium, which is transmitted from cat to cat via the cat flea (Ctenocephalides felis). 4 Several new Bartonella spp or subspecies have been identified in domestic cats and dogs and free-ranging or captive wild felids or canids. Furthermore, many new species of Bartonella have been identified in a wide range of mammals, including rodents and ruminants. There is also an increasing number of reports of infections in humans and dogs caused by Bartonella spp associated with rodents. Morphologic and Biological Features Members of the genus Bartonella are short, pleo-morphic, gram-negative rod bacteria; they are fastidious, aerobic, and oxidase-negative organisms. They belong to the α 2 subgroup of the class Proteobacteria and are closely related to the genera Brucella, Agrobacterium, and Rhizobium. 1 They are mainly hemotropic, intraerythro-cytic bacteria. Isolation of the organisms is usually achieved via bacteriologic culture of blood after partial lysis of the erythrocytes. In culture, Bartonella organisms require specific axenic media (enriched with rabbit or horse blood), and for most of these bacteria, the culture must be performed at 35 o C with an atmosphere containing 5% carbon dioxide. Growth of primary isolates occurs after several days (usually more than a week) to several weeks. 1,3 Identification of the bacteria is mainly based on results of polymerase chain reaction (PCR) assay and sometimes findings of partial sequenc-ing of specific genes (eg, 16S rRNA, citrate synthase, and groEL). Via pulsed field gel electrophoresis, B henselae DNA has a wide range of profiles, compared with profiles of B clarridgeiae. Four Bartonella spp have been isolated from domestic cats. Domestic cats appear to be the …