A Case of Thoracic Empyema Caused by Actinomyces naeslundii

Our plain-English summary of A Case of Thoracic Empyema Caused by Actinomyces naeslundii, by Y. Matsubayashi, K. Mizuno, T. Yamashita, et al (The American Journal of Case Reports, 2024).

The study

• Authors: Y. Matsubayashi, K. Mizuno, T. Yamashita, K. Asai
• Journal: The American Journal of Case Reports
• Published: 2024;25:e943030
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

BACKGROUND Actinomycosis is a clinically significant but uncommon infectious disease caused by anaerobic commensals of Actinomyces species, and the incidence of thoracic empyema is rare. We report an extremely rare case of empyema caused by Actinomyces naeslundii (A. naeslundii). CASE REPORT A 39-year-old man presented to our hospital with fever and dyspnea. He had massive pleural effusion and was diagnosed with a left lower-lobe abscess and left thoracic empyema. Thoracic drainage was performed and Ampicillin/Sulbactam was administered for 3 weeks. Four years later, the patient presented with back pain, and chest X-ray showed increased left pleural effusion. After close examination, malignant pleural mesothelioma was suspected, and computed tomography-guided needle biopsy was performed, which yielded a viscous purulent pleural effusion with numerous greenish-yellow sulfur granules. A. naeslundii was identified through anaerobic culture. Thoracoscopic surgery of the empyema cavity was conducted, and Ampicillin/Sulbactam followed by Amoxicillin/Clavulanate was administered for approximately 6 months. No recurrence has been observed for 1 year since the surgical procedure. CONCLUSIONS Actinomyces empyema is a rare condition, and this case is the second reported occurrence of empyema caused by A. naeslundii. The visual identification of sulfur granules contributed to the diagnosis. Long-term antibiotic therapy plays a crucial role in treatment.

In plain English

This case report describes one patient in Japan, a 39-year-old man with a chest infection caused by the bacterium Actinomyces naeslundii. It does not discuss asbestos. The patient first had fever and shortness of breath and was diagnosed with a left lower-lobe lung abscess and left thoracic empyema, which is pus in the chest cavity. The chest was drained and antibiotics were given. The pleural fluid culture was negative. Four years later the patient had back pain and a mass with pleural thickening at the site of the old empyema, and malignant pleural mesothelioma was suspected. A first needle biopsy found no apparent malignant cells. A second biopsy drew thick pus containing greenish-yellow sulfur granules, and A. naeslundii grew in anaerobic culture. This established a diagnosis of empyema caused by this bacterium. After thoracoscopic surgery and about six months of oral antibiotics, no recurrence had been seen one year after surgery. The authors concluded that this was the second reported case of empyema caused by A. naeslundii and that long-term antibiotic therapy plays a crucial role in treatment.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report (single patient)
• Who was studied: One 39-year-old man treated at Hamamatsu Medical Center, Hamamatsu, Shizuoka, Japan
• Exposure: No asbestos exposure is reported. The case concerns infection with the bacterium Actinomyces naeslundii. The authors linked the patient's mild periodontal disease to the lung abscess that progressed to empyema.
• Main results:
  • At the first presentation, the patient was diagnosed with a left lower-lobe lung abscess and thoracic empyema and underwent drainage. The pleural fluid culture was negative.
  • Four years later, imaging showed a mass with pleural thickening at the site of the previous empyema cavity. Malignant pleural mesothelioma was suspected.
  • The first CT-guided needle biopsy showed granulation tissue with no apparent malignant cells.
  • A second CT-guided biopsy yielded viscous purulent pleural fluid containing greenish-yellow sulfur granules.
  • A. naeslundii was identified by anaerobic culture, establishing the diagnosis of thoracic empyema caused by A. naeslundii.
  • After thoracoscopic surgery, the patient received intravenous then oral antibiotics. The oral antibiotic (AMPC/CVA) was continued for about 6 months.
  • No evidence of recurrence had been observed 1 year after surgery.
• The authors' conclusion: The authors concluded that this case was the second reported instance of empyema caused by A. naeslundii. They wrote that seeing the sulfur granules contributed to the diagnosis, and that long-term antibiotic therapy plays a crucial role in treating actinomycosis.
• Limitations the authors state:
  • The authors state that the first episode may also have been A. naeslundii empyema, but the organism could not be confirmed at that time.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Empyema, Dyspnea, Pleural Effusion, Chest X-Ray, Pleural Mesothelioma, Needle Biopsy.

Related studies

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• Salvage therapy with topical antifungal for Aspergillus fumigatus empyema complicating extrapleural pneumonectomy — M. Purohit, A. Guleri, et al. (2012)
• Postoperative Empyema Due to Leclercia adecarboxylata Following Mesothelioma Surgery: A Case Report — J.F. Montenegro, M.Á. Diaz-Diaz, et al. (2025)
• Awake video-assisted pleural decortication for empyema thoracis — F. Tacconi, E. Pompeo, et al. (2010)
• A novel diagnostic method for distinguishing parapneumonic effusion and empyema from other diseases by using the pleural lactate dehydrogenase to adenosine deaminase ratio and carcinoembryonic antigen levels — T. Saraya, K. Ohkuma, et al. (2019)
• Video-Thoracoscopic Management of Postpneumonectomy Empyema — D. Galetta, L. Spaggiari (2018)

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