Evaluation of serological response to Bartonella henselae, Bartonella quintana and Afipia felis antigens in 64 patients with suspected cat-scratch disease

The serological response to Bartonella henselae, B. quintana, and Afipia felis was assessed by an indirect fluorescence antibody test (IFAT) in 64 patients with suspected cat-scratch disease (CSD) recruited from the Bordeaux area in France. Blood samples were collected from 57 patients with chronic lymphadenopathy who underwent lymph-node biopsy with suggestive histopathologic features of CSD, and from an additional 7 patients with suspected CSD who underwent surgical incision and drainage because of lymph-node tenderness. Of the patients, 31 were male and 33 female, with a median age of 27 years (range 2-89). 69.8% reported cat and/or dog contact. Of the 26/61 (40.6%) patients, serum samples were positive at a titer of 1:100 or more for immunoglobulin G (IgC) antibodies (17 only to B. henselae, 1 only to B. quintana, 3 only to Afipia felis, and 5 to both B. henselae and B. quintana). IgM or IgA antibodies mere also detected in 10 patients with IgG antibodies to B. henselae. 11 (17.2%) of the 64 patient serum samples were positive at a low titer of 1:50. These data suggested that serological response assessed by standard IFAT is not enough to confirm a CSD diagnosis.