Systematic serological testing in infective endocarditis: Limited clinical impact despite high usage-a 14-year cohort study

Abstract

Objectives: To evaluate the clinical utility of systematic serological testing in infective endocarditis (IE), determine the prevalence of blood-culture negative IE (BCNIE), and characterize its clinical presentation in our cohort.

Methods: Retrospective analysis of 296 consecutive IE episodes (2008-2021) at a tertiary hospital. We compared clinical characteristics, serological testing patterns, and outcomes between BCNIE and blood-culture-positive IE (BCPIE) cases.

Results: BCNIE accounted for 22.3% (66/296) of cases. Prior antibiotic use was significantly higher in BCNIE (27.3% vs 2.2%, P < 0.001). Serological testing was performed in 81.8% of BCNIE and 71.3% of BCPIE cases. Despite positive serological results for Coxiella burnetii phase I IgG (24.2% of tested cases), Bartonella henselae IgG (14.9%), Mycoplasma pneumoniae IgM (6.9%), and Brucella spp. (1.5%), only one patient (1.9% of all positive results) received targeted antimicrobial therapy. In multivariate analysis, no serological marker was associated with improved clinical outcomes.

Conclusions: Systematic serological testing in IE provides limited diagnostic and therapeutic value. A selective approach targeting BCNIE cases with specific epidemiological risk factors appears more appropriate and cost-effective.

Keywords: Blood culture; Diagnostic utility; Infective endocarditis; Serology.