A case of empyema caused by Streptococcus pyogenes in an immunocompetent adult: a rare pulmonary manifestation.

Streptococcus pyogenes (Group A Streptococcus) is an aerobic, gram-positive bacterium responsible for various infections such as pharyngitis, cellulitis, erysipelas, and necrotizing fasciitis. Though it rarely affects the lower respiratory tract, it can, in uncommon cases, cause community-acquired pneumonia. This study presents a rare case of rapidly progressing pneumonia caused by S. pyogenes, complicated by empyema. A 52-year-old woman presented to the emergency department with symptoms of cough, yellow sputum, night sweats, and left-sided chest pain. Initial empirical treatment with piperacillin-tazobactam was escalated to meropenem and vancomycin due to increased inflammatory markers and positive blood cultures. Blood and sputum cultures identified S. pyogenes using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Susceptibility testing confirmed sensitivity to penicillin-class antibiotics, leading to targeted therapy with ceftriaxone, ampicillin-sulbactam, and later, oral amoxicillin-clavulanate. Despite appropriate antibiotics and tube thoracostomy, no significant clinical improvement was observed. Intrapleural fibrinolytic therapy was initiated, and a favorable response was achieved through the combination of antibiotics, drainage, and fibrinolytics. The patient was ultimately discharged in good condition. In conclusion, although S. pyogenes is an uncommon cause of community-acquired pneumonia, it should be considered in cases with rapid progression and empyema complications.