Pediatric Bartonella henselae Infection: The Role of Serologic Diagnosis and a Proposed Clinical Approach for Suspected Acute Disease in the Immunocompetent Child.

Abstract

Bartonella henselae serology is commonly used to diagnose cat-scratch disease (CSD). Titers above a threshold for positivity suggest either a recent or remote infection. Recent infection can be confirmed by a 4-fold rise in the convalescent titer in some cases. Many atypical presentations attributed to CSD utilize a low threshold for positivity without supportive evidence from convalescent sera or supplemental testing, raising a concern for the overdiagnosis of CSD. We conducted a retrospective chart review of immunocompetent pediatric patients at the Hospital for Sick Children, Toronto, spanning an 11-year period. A total of 154 cases were included with serologic titers ≥1:128. These were divided into 3 groups: group 1 = 1:128, group 2 = 1:256, and group 3 ≥ 1:512. Cases within groups were evaluated with respect to cat contact, clinical presentation, further testing, and final diagnosis. One-third of patients with a titer of 1:128 had an alternative diagnosis. Most cases with a titer of 1:128 or 1:256 did not have convalescent serologic testing performed. Within these 2 groups, only 1 case had a 4-fold rise in the convalescent titer. A trend of decreasing number of cases with alternative diagnoses (P = 0.03) and increasing number of cases presenting with regional lymphadenopathy (P = 0.07) was associated with higher titers in group 3 compared with group 1. Concerns about the serologic diagnosis of CSD include the use of low titers for positivity, incomplete diagnostic evaluation, and the lack of convalescent serologic testing. We propose a clinical guide to assist in managing suspected cases of CSD.