Use of Cell-Free DNA Testing to Diagnose Infective Endocarditis in a Patient With Negative Blood Cultures

Infective endocarditis (IE) is associated with significant morbidity and mortality. Its diagnosis can be especially challenging, as can the identification of a causative pathogen, which, in turn, is crucial for appropriate management. Here, we present a rare case of Streptococcus intermedius endocarditis complicated by lung and cerebral abscess in which clinicians employed cell-free deoxyribonucleic acid (cfDNA) testing to confirm the diagnosis, establish a causative pathogen, and determine appropriate antibiotic therapy. Notably, the positive cfDNA test prevented the need for brain biopsy in this case and has implications for diagnostic and therapeutic guidelines.