Encapsulated empyema refers to the localized accumulation of pus within the pleural cavity, most commonly caused by pathogens such asStreptococcus pneumoniae andStaphylococcus aureus. However, cases caused by the oral anaerobePorphyromonas gingivalis are relatively rare. This article reports the case of a 56-year-old male patient who presented with intermittent cough and expectoration of yellow purulent sputum for 1 year, which worsened and was accompanied by dyspnea one day prior to admission. Chest CT revealed bilateral lung infection and right-sided hydropneumothorax with encapsulated effusion. The pleural fluid appeared chocolate-colored and turbid, with routine biochemical analysis consistent with empyema. Targeted next-generation sequencing for pathogens detected a significant number ofPorphyromonas gingivalis sequences in the pleural fluid. Combined with the patient's history of gingival bleeding, a diagnosis of right-sided encapsulated empyema caused byPorphyromonas gingivalis was made. The patient was treated with meropenem as targeted anti-infective therapy, along with thoracic drainage and thoracoscopic adhesiolysis. Following treatment, the patient's clinical symptoms and imaging findings showed marked improvement. Combined with a literature review, this article summarizes the clinical features, diagnostic approach, and treatment strategies for this rare infection to enhance clinical awareness.

1. NeuhofH,CoplemanB.Encapsulated empyema[J].Am J Surg,1941,54(1):39‑49.

2. HassanM,CargillT,HarrissE,et al.The microbiology of pleural infection in adults: a systematic review[J].Eur Respir J,2019,54(3):1900542.

3. DyrhovdenR,EaganTM,FløttenØ,et al.Pleural empyema caused by streptococcus intermedius and fusobacterium nucleatum: a distinct entity of pleural infections[J].Clin Infect Dis,2023,77(10):1361‑1371.

4. DyrhovdenR,NygaardRM,PatelR,et al.The bacterial aetiology of pleural empyema. A descriptive and comparative metagenomic study[J].Clin Microbiol Infect,2019,25(8):981‑986.

5. HowKY,SongKP,ChanKG.Porphyromonas gingivalis: an overview of periodontopathic pathogen below the gum line[J].Front Microbiol,2016,7:53.

6. MysakJ,PodzimekS,SommerovaP,et al.Porphyromonas gingivalis: major periodontopathic pathogen overview[J].J Immunol Res,2014,2014:476068.

7. ScannapiecoFA.Role of oral bacteria in respiratory infection[J].J Periodontol,1999,70(7):793‑802.

8. ZhangY,ZhuY,WanH.Case report:multiple abscesses caused by Porphyromonas gingivalis diagnosed by metagenomic next‑generation sequencing[J].Front Med (Lausanne),2023,9:1089863.

9. TanakaA,KogamiM,NagatomoY,et al.Subcutaneous abscess due to empyema necessitans caused by Porphyromonas gingivalis in a patient with periodontitis[J].IDCases,2022,27:e01458.

10. RasheedA,KhawchareonpornT,MuengtaweepongsaS,et al.An unusual presentation of subdural empyema caused by porphyromonas gingivalis[J].Ann Indian Acad Neurol,2013,16(4):723‑725.

11. HuangG,ZhouX,ZhangZ,et al.Acute Porphyromonas gingivalis subdural abscess with brain abscess in the left temporal lobe: a case report and review of literature[J].Infect Drug Resist,2023,16:6487‑6491.

12. CaiDH,FangXL.Pyopneumothorax caused by trichomonas tenax and porphyromonas endodontalis coinfection in a patient with previous cerebral infarction: a case report and literature review[J].Infect Drug Resist,2022,15:6101‑6108.

13. ShaJ,ShaoJ,LuS,et al.Pyopneumothorax with bronchopleural fistula due to pulmonary infection caused by Porphyromonas gingivalis in a patient with periodontitis[J].Clin Respir J,2023,17(9):962‑965.

14. 梁新乐,白智远.牙龈卟啉单胞菌合并咽峡炎链球菌致包裹性脓胸1例[J].中国临床案例成果数据库,2025,7(1):E1303.LiangXL,BaiZY.One case of encapsulated empyema caused by Porphyromonas gingivalis combined with Streptococcus pharyngitis[J].Chinese Medical Case Repository,2025,7 (1):E1303.

15. BertelsenRJ,BarrionuevoAMP,ShigdelR,et al.Association of oral bacteria with oral hygiene habits and self‑reported gingival bleeding[J].J Clin Periodontol,2022,49(8):768‑781.

16. de JonghCA,de VriesTJ,BikkerFJ,et al.Mechanisms of Porphyromonas gingivalis to translocate over the oral mucosa and other tissue barriers[J].J Oral Microbiol,2023,15(1):2205291.

17. De JonghCA,BikkerFJ,De VriesTJ,et al.Porphyromonas gingivalis interaction with Candida albicans allows for aerobic escape, virulence and adherence[J].Biofilm,2024,7:100172.

18. AsaiN,SuematsuH,HagiharaM,et al.The etiology and bacteriology of healthcare‑associated empyema are quite different from those of community‑acquired empyema[J].J Infect Chemother,2017,23(10):661‑667.

19. FisherMC.Lung abscess and other anaerobic pulmonary infections[J].Semin Pediatr Infect Dis,1998,9(3):199‑204.

20. LightRW.Parapneumonic effusions and empyema[J].Proc Am Thorac Soc,2006,3(1):75‑80.

21. BartlettJG.Anaerobic bacterial infection of the lung[J].Anaerobe,2012,18(2):235‑239.

22. LiuY,WangR,YuanY,et al.Comparison of targeted next‑generation sequencing and traditional microbial culture in the diagnosis of pulmonary infections[J].Diagn Microbiol Infect Dis,2024,110(4):116534.

23. DongY,ChenQ,TianB,et al.Advancing microbe detection for lower respiratory tract infection diagnosis and management with metagenomic next‑generation sequencing[J].Infect Drug Resist,2023,16:677‑694.

24. RodinoKG,SimnerPJ.Status check: next‑generation sequencing for infectious‑disease diagnostics[J].J Clin Invest,2026,134(4):e178003.

25. 中国医学装备协会检验医学分会.靶向二代测序在感染性疾病诊疗中的规范化应用专家共识2025[J].中华检验医学杂志,2025,48(4):469‑477.Branch of Laboratory Medicine, China Association of Medical Equipment.Expert consensus on standardized application of targeted next-generation sequencing in the diagnosis and treatment of infectious diseases (2025)[J].Chinese Journal of Laboratory Medicine,2025,48(4):469-477.

26. QinL,LiangM,SongJ,et al.Utilizing targeted next‑generation sequencing for rapid, accurate, and cost‑effective pathogen detection in lower respiratory tract infections[J].Infect Drug Resist,2025,18:329‑340.

27. PsallidasI,CorcoranJP,RahmanNM.Management of parapneumonic effusions and empyema[J].Semin Respir Crit Care Med,2014,35(6):715‑722.

28. KanekoA,IwabuchiH,SatoJ,et al.Antimicrobial susceptibility surveillance of bacterial isolates recovered in Japan from odontogenic infections in 2018[J].J Infect Chemother,2025,31(7):102731.

29. DahlenG,PreusHR.Low antibiotic resistance among anaerobic gram‑negative bacteria in periodontitis 5 years following metronidazole therapy[J].Anaerobe,2017,43:94‑98.

30. GauzitR,CastanB,BonnetE,et al.Anti‑infectious treatment duration: the SPILF and GPIP french guidelines and recommendations[J].Infect Dis Now,2021,51 (2):114‑139.

31. DaviesHE,DaviesRJO,DaviesCWH.Management of pleural infection in adults: british thoracic society pleural disease guideline 2010[J].Thorax,2010,65(Suppl 2): ii41‑ii53.

32. ShenKR,BribriescoA,CrabtreeT,et al.The American Association for Thoracic Surgery consensus guidelines for the management of empyema[J].J Thorac Cardiovasc Surg,2017,153(6):e129‑e146.

33. SemenkovichTR,OlsenMA,PuriV,et al.Current state of empyema management[J].Ann Thorac Surg,2018,105(6):1589‑1596.

34. AvnerBS,GinosyanA,LeJ,et al.Analysis of antibiotic use and clinical outcomes in adults with known and suspected pleural empyema[J].BMC Infect Dis,2022,22(1):783.