Alattas NH, Patel SN, Richardson SE, et al. - For diagnosing cat-scratch disease (CSD), Bartonella henselae serology is commonly employed. A recent or remote infection is suggested by titers above a threshold for positivity. In some cases, a 4-fold rise in the convalescent titer confirms recent infection. A low threshold for positivity is used in many atypical presentations attributed to CSD without supportive evidence from convalescent sera or supplemental testing, raising a concern for the overdiagnosis of CSD. Researchers conducted a retrospective chart review of 154 immunocompetent pediatric patients at the Hospital for Sick Children, Toronto, spanning an 11-year period. Participants were divided into 3 groups: group 1 = 1:128, group 2 = 1:256, and group 3 ≥ 1:512. Among participants, an alternative diagnosis was made in one-third of patients with a titer of 1:128. Compared with group 1, group 3 exhibited higher titers in correlation with a trend of decreasing number of cases with alternative diagnoses and increasing number of cases presenting with regional lymphadenopathy. Following are the concerns regarding the serologic diagnosis of CSD: the use of low titers for positivity, incomplete diagnostic evaluation, and the lack of convalescent serologic testing. A clinical guide was proposed that may aid in managing suspected cases of CSD.