Pleural Empyema Caused by Streptococcus Constellatus in an Immunocompetent Young Adult: A Case Report

Objective: Members of the Streptococcus anginosus group (SAG) are associated with deep-seated and purulent infections. Pleural empyema caused by Streptococcus constellatus is rare and is more commonly reported in immunocompromised individuals. This report describes a case of S. constellatus-associated pleural empyema in a young adult without identifiable predisposing risk factors.Methods: A 35-year-old male with no history of comorbid disease or immunosuppression presented with progressive dyspnea and pleuritic chest pain. Laboratory investigations revealed leukocytosis and elevated inflammatory markers. Thoracic computed tomography demonstrated loculated pleural fluid collections in the right hemithorax. Initial management consisted of tube thoracostomy. Due to insufficient drainage and incomplete lung expansion, video-assisted thoracoscopic surgery (VATS) was performed. Pleural fluid samples were obtained for microbiological analysis.Results: Intraoperatively, dense fibrinous septations and abundant purulent material were observed, and loculations were disrupted to achieve adequate drainage and pleural cavity irrigation. Pleural fluid culture yielded Streptococcus constellatus, while blood cultures were negative. Antibiotic therapy was adjusted according to the antibiogram results. During follow-up, marked clinical and radiological improvement was observed without the development of systemic sepsis.Conclusions: Although uncommon, S. constellatus can cause invasive and organized-phase empyema even in immunocompetent individuals. In cases of loculated or treatment-resistant pleural infection, SAG members should be considered as potential pathogens, and management should include timely surgical intervention combined with culture-guided targeted antimicrobial therapy.