Purulent Pericarditis Caused by Polymicrobial Periodontal Pathogens (Tannerella forsythia, Fusobacterium nucleatum, and Porphyromonas gingivalis): A Case Report and Literature Review

Background: Purulent pericarditis is a rare, life-threatening infection, most commonly caused by bacteria such as Staphylococcus aureus . We report an exceptional case of hematogenously disseminated infection probably originating from the oral cavity, highlighting a novel pathogen profile. Case Presentation: We report a 66-year-old male with no history of periodontal disease or oral procedures presented with purulent pericarditis and a concomitant subphrenic abscess. Metagenomic next-generation sequencing (mNGS) of pericardial fluid revealed a polymicrobial infection with three periodontal pathogens: Tannerella forsythia, Fusobacterium nucleatum , and Porphyromonas gingivalis . The patient was treated with pericardiocentesis, targeted antibiotics, and organ support, resulting in clinical stabilization. Conclusion: This case provides clinical evidence that a consortium of periodontal pathogens can disseminate hematogenously to cause severe metastatic infections in sterile sites, even in individuals without overt oral disease. It underscores the need to consider occult oral origins in infections of unknown source and illustrates the value of comprehensive molecular diagnostics in identifying fastidious organisms, although it remains undetermined whether both conditions were secondary to the same source.