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Bartonella species are fastidious, facultative intracellular, slow-growing, gram-negative bacteria that cause a broad spectrum of diseases in humans. This genus includes at least 27 distinct species or subspecies, of which at least 13 have been recognized as confirmed or potential human pathogens; B. bacilliformis, B. quintana, and B. henselae are most commonly identified (Table 160-1). Most Bartonella species have successfully adapted to survival in specific domestic or wild mammals. Prolonged intraerythrocytic infection in these animals creates a reservoir for human infections. B. bacilliformis and B. quintana, which are not zoonotic, are exceptions to this rule. Arthropod vectors are often involved. Isolation and characterization of Bartonella species are difficult and require special techniques. Clinical presentation generally depends on both the infecting Bartonella species and the immune status of the infected individual. Bartonella species are susceptible to many antibiotics in vitro; however, clinical responses to therapy and studies in animal models suggest that the minimal inhibitory concentrations of many antimicrobial agents correlate poorly with the drugs′ in vivo efficacies in patients with Bartonella infections.

Table 160-1 Bartonella Species Known or Suspected to Be Human Pathogens

Definition and Etiology

Usually a self-limited illness, cat-scratch disease (CSD) has two general clinical presentations. Typical CSD, the more common, is characterized by subacute regional lymphadenopathy; atypical CSD is the collective designation for numerous extranodal manifestations involving various organs. B. henselae is the principal etiologic agent of CSD. Rare cases have been associated with Afipia felis and B. quintana; B. clarridgeiae may occasionally be involved as well.


CSD occurs worldwide, favoring warm and humid climates. In temperate climates, incidence peaks during fall and winter; in the tropics, disease occurs year-round. Adults are affected nearly as frequently as children. ...

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