A diagnosis of CSD is made on the basis of characteristic clinical features together with confirmatory serologic testing. The indirect fluorescent antibody assay for the detection of serum anti–B henselae antibodies is 88% sensitive and 94% specific, with titers of greater than 1:64 considered positive. Enzyme immunoassays with a sensitivity for IgG of 86%–95% and a specificity of 96%, together with Western blot analysis, have also been developed. A single positive indirect fluorescent antibody or enzyme immunoassay titer for IgG or IgM is sufficient to confirm the diagnosis of CSD. Other diagnostic approaches include bacterial cultures, which may require several weeks for colonies to become apparent; skin testing, which has a sensitivity of up to 100% and a specificity of up to 98%; and PCR-based techniques that target the bacterial 16S ribosomal RNA gene or B henselae DNA.
Excerpted from BCSC 2020-2021 series: Section 9 - Uveitis and Ocular Inflammation. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.