A case report of fulminant primary purulent pericarditis due to Streptococcus pyogenes presenting with cardiac tamponade in a seemingly immunocompetent adult.

BACKGROUND: Primary purulent pericarditis due to Streptococcus pyogenes is exceedingly rare in adults, with fewer than 10 cases reported in the literature to date. Most reported cases have occurred in the setting of an immunocompromised state, thoracic procedures, or identifiable infectious foci. CASE SUMMARY: A 63-year-old immunocompetent man experiencing homelessness with a past medical history of alcohol-use disorder and plaque psoriasis presented in acute hypoxemic respiratory failure. Transthoracic echocardiography revealed a large fibrinous pericardial effusion with tamponade physiology. Emergent pericardiocentesis yielded 600 ml of purulent fluid, and cultures grew S. pyogenes. Despite appropriate antimicrobial therapy, recurrent pericardial effusion developed, necessitating creation of a pericardial window. Extensive infectious and immunologic evaluation did not identify an underlying immunodeficiency or primary source. The hospital course was complicated by secondary infections, progressive multi-organ failure, septic shock, and death on hospital Day 61. DISCUSSION: Purulent pericarditis secondary to S. pyogenes remains an extremely rare diagnosis with a high mortality rate. This aggressive case is striking, given the absence of a clear infectious nidus and the need for early recognition and definitive source control. This case report emphasizes multiple aetiologies of purulent pericarditis, regardless of perceived source, especially those of undomiciled status or facing ongoing social inequities.