Cell-Free DNA Reveals Hidden Streptococcus anginosus in Cryptogenic Purulent Pericarditis in a Young Adult

BACKGROUND Bacterial purulent pericarditis is rare and can be fatal if not treated appropriately. Streptococcus anginosus can cause invasive and cryptogenic infections, and purulent pericarditis is an uncommon presentation. Alcohol abuse can be a risk factor for abscesses caused by this agent. Cell-free DNA testing is a noninvasive method that has great potential in cases of serious infections in which pathogens are not easily identifiable by traditional microbiological techniques. CASE REPORT A 27-year-old man reported alcohol abuse and was hospitalized for acute pericarditis without signs of severity. He developed cardiac tamponade on the fifth day of hospitalization, requiring emergency pericardiocentesis. A significant persistent pericardial effusion was observed. Videopericardiectomy revealed a large amount of fibrin and purulent secretion in the pericardial sac. Additional tests and cultures did not identify systemic disease or an etiological agent. A cell-free DNA assay identified S. anginosus. He was discharged after 4 weeks of broad-spectrum antimicrobial therapy. There was no progression to constrictive pericarditis. CONCLUSIONS We present a case of purulent bacterial pericarditis with a cryptogenic focus in a young adult patient with a history of alcohol, marijuana, and e-cigarette abuse. He developed cardiac tamponade but received rapid and appropriate in-hospital therapeutic support, with clinical recovery within a few weeks. Alcohol and smoking may have facilitated bacterial translocation from the oropharynx to the bloodstream and then to the pericardium. S. anginosus was identified only by molecular research.