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

Background: 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. Case Description: 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 Conclusions: 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.