Cat-scratch disease is an infection caused byBartonella henselae,a fastidious gram-negative bacillus acquired from exposure to an infected kitten or cat. The most common manifestation of human disease is lymphadenitis. Atypical forms of infection include Parinaud oculoglandular syndrome, stellate neuroretinitis, persistent fever without localizing signs, hepatosplenic infection, encephalopathy, osteomyelitis, and endocarditis. Immunocompromised individuals withB. hensalaeinfection may develop bacillary angiomatosis, bacillary peliosis, and relapsing bacteremia with fever syndrome. The bacillus is susceptible to several antibacterial agentsin vitro, including penicillins, cephalosporins, aminoglycosides, tetracyclines, macrolides, quinolones, trimethoprim and sulfamethoxazole, and rifampin. Greatest clinical efficacy has been observed following treatment with rifampin, ciprofloxacin, gentamicin, trimethoprim and sulfamethoxazole, clarithromycin, and azithromycin. In one placebo-controlled study, azithromycin therapy was associated with more rapid diminution in size of infected lymph nodes. The majority of cases of cat-scratch disease occurring in normal hosts do not require anti-infective therapy for resolution of infection.