[A case of cat scratch disease identified by an elevated Bartonella henselae antibody level using enzyme immunoassay]

A 68-year-old male was admitted to our hospital because of fever and a 2-week history of inguinal adenomegaly. Since he owned a cat, cat scratch disease was suspected. But it was necessary to distinguish cat scratch disease from lymphoma type adult T-cell leukemia because he showed a high level of antibody against HTLV-1. An excisional biopsy of the inguinal node was performed. Histopathologic examination revealed abscess-forming granulomatous lymphadenitis compatible with cat scratch disease. A Warthin-Starry silver stain showed pleomorphic bacilli in the lymph node. So we confirmed a serological response to Bartonella henselae, the causative agent of cat scratch disease, using enzyme immunoassay (EIA). The IgG antibody level to B. henselae was positive at 42 EIA Unit before treatment. After treatment with intravenous cefepime and oral tosufloxacin, his physical symptoms improved and the antibody level decreased to less than 12 EIA Unit. EIA was very useful for diagnosis of this case. Serology to B. henselae may replace traditional diagnostic criteria for cat scratch disease.