Severe empyema caused by mixed oral anaerobic bacterial infection: a case report

Empyema is a life-threatening pleural infection that can result from various bacterial sources. While oral anaerobic bacteria are recognized as potential pathogens, severe empyema caused by mixed oral anaerobic bacterial infection remains clinically rare. Recent advances in metagenomic next-generation sequencing (NGS) have improved the etiological diagnosis of complex infections. This case demonstrates the clinical significance of NGS technology and oral health in preventing systemic infections.

An 80-year-old male with poor oral hygiene and multiple dental caries presented with acute onset of left-sided chest pain, chills, and fever. Physical examination revealed diminished breath sounds over the left lung. Imaging studies confirmed left-sided empyema. Pleural fluid NGS identified mixed oral anaerobic bacteria including Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, and Finegoldia magna. The patient underwent thoracoscopic empyema debridement, with postoperative tissue pathology showing suppurative inflammation with fibrinous necrosis. Surgically excised tissue NGS additionally detected Finegoldia magna along with Epstein-Barr virus and human herpesvirus 6. Following targeted anti-infective therapy with meropenem and metronidazole, the patient recovered successfully.

This case highlights the critical role of NGS technology in identifying mixed oral anaerobic pathogens and guiding precision-targeted treatment of empyema. The atypical presentation of empyema caused by oral anaerobic bacteria warrants early surgical intervention combined with appropriate antimicrobial therapy. Our findings emphasize the importance of oral health maintenance in preventing life-threatening systemic infections and broaden our understanding of oral-systemic disease relationships.