Recommendations for Treatment of Human Infections Caused by Bartonella Species

Abstract

Members of the genus Bartonella are facultative intracellular bacteria belonging to the alpha 2 subgroup of the class Pro- teobacteria and are phylogenetically closely related to Brucella species (15, 73). Until 1993, only three diseases were known to be caused by Bartonella species: Carrion's disease (Bar- tonella bacilliformis), trench fever (Bartonella quintana), and cat scratch disease (CSD; Bartonella henselae). The genus now comprises B. bacilliformis, species of the former genera Roch- alimea and Grahamella (14, 18), and additional, recently de- scribed species (Table 1). In mammals, each Bartonella species is highly adapted to its reservoir host; the bacteria can persist in the bloodstream of the host as the result of intraerythrocytic parasitism (49). Intraerythrocytic localization of B. henselae has been demonstrated in cat erythrocytes (88), and B. bacil- liformis bacilli have been observed within erythrocytes during the acute phase of Carrion's disease (Oroya fever) (88). Bar- tonellae also have a tropism for endothelial cells, and intracel- lular B. henselae can be identified in endothelial cells infected in vitro (28), although intraendothelial cell bacilli have not been identified in vivo. Bartonella species cause long-recognized diseases, such as Carrion's disease, trench fever, and CSD, and more recently recognized diseases, such as bacillary angiomatosis (BA), pe- liosis hepatis (PH), chronic bacteremia, endocarditis, chronic lymphadenopathy, and neurological disorders (Table 2) (73). A remarkable feature of the genus Bartonella is the ability of a single species to cause either acute or chronic infection and either vascular proliferative or suppurative manifestations. The pathological response to infection with Bartonella spp. varies substantially with the status of the host immune system. Indeed, infection with the same Bartonella species (e.g., B. henselae) can result in a focal suppurative reaction (CSD in immunocompetent patients), a multifocal angioproliferative response (BA in immunocompromised patients), endovascular multiplication of the bacteria (endocarditis), or an exaggerated inflammatory response without evidence of bacteria in patient tissues (meningoencephalitis) (86). Some of the diseases due to Bartonella species can resolve spontaneously without treatment, but in other cases, the dis- ease is fatal without antibiotic treatment and/or surgery. The clinical situations are so different that a single treatment for all Bartonella-related diseases has not been identified, and the approach to treatment must be adapted to each species and clinical situation (49). Moreover, the database of clinical stud- ies with a standard case definition, culture confirmation, rigidly defined disease outcomes, and patients with similar host de- fenses is very limited. Thus, case reports with a very limited number of subjects often serve to dictate therapy. The objec- tive of this minireview is to summarize the antibiotic treatment recommendations for the different infections caused by Bar-