Actinomyces meyeri pleural infection that was difficult to treat due to delayed culture: A case report and literature review of 28 cases

Polymicrobial infections with specific Actinomyces and related organisms, using the current taxonomy

Actinomyces organisms reside on mucosal surfaces of the oropharynx and the genitourinary tract. Polymicrobial infections with Actinomyces organisms are increasingly being reported in the literature. Since these infections differ from classical actinomycosis, lacking of specific clinical and imaging findings, slow-growing Actinomyces organisms can be regarded as contaminants or insignificant findings. In addition, only limited knowledge is available about novel Actinomyces species and their clinical relevance. The recent reclassifications have resulted in the transfer of several Actinomyces species to novel genera Bowdeniella, Gleimia, Pauljensenia, Schaalia, or Winkia. The spectrum of diseases associated with specific members of Actinomyces and these related genera varies. In human infections, the most common species are Actinomyces israelii, Schaalia meyeri, and Schaalia odontolytica, which are typical inhabitants of the mouth, and Gleimia europaea, Schaalia turicensis, and Winkia neuii. In this narrative review, the purpose was to gather information on the emerging role of specific organisms within the Actinomyces and related genera in polymicrobial infections. These include Actinomyces graevenitzii in pulmonary infections, S. meyeri in brain abscesses and infections in the lower respiratory tract, S. turicensis in skin-related infections, G. europaea in necrotizing fasciitis and skin abscesses, and W. neuii in infected tissues around prostheses and devices. Increased understanding of the role of Actinomyces and related species in polymicrobial infections could provide improved outcomes for patient care. Key messages Due to the reclassification of the genus, many former Actinomyces species belong to novel genera Bowdeniella, Gleimia, Pauljensenia, Schaalia, or Winkia.Some of the species play emerging roles in specific infection types in humans.Increasing awareness of their clinical relevance as an established or a putative pathogen in polymicrobial infections brings about improved outcomes for patient care.

A Case of Thoracic Empyema Caused by Actinomyces naeslundii

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.

Pulmonary Actinomyces graevenitzii Infection: Case Report and Review of the Literature

Background

Pulmonary actinomycosis (PA), a chronic indolent infection, is a diagnostic challenge. Actinomyces graevenitzii is a relatively rare Actinomyces species isolated from various clinical samples.

Case Presentation

A 47-year-old patient presented with a 3-month history of mucopurulent expectoration and dyspnea and a 3-day history of fever up to 39.0°C. He had dental caries and a history of alcoholism. Computed tomography (CT) images of the chest revealed a consolidation shadow in the right upper and middle lobes, with necrosis containing foci of air. Actinomyces graevenitzii was isolated from bronchoalveolar lavage fluid (BALF) culture and was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. He received treatment with intravenous piperacillin-sulbactam for 10 days and oral amoxicillin-clavulanate for 7 months. His clinical condition had considerably improved. The consolidation shadow was gradually absorbed.

Conclusion

Early diagnosis and treatment of pulmonary actinomycosis are crucial. Bronchoscopy plays a key role in the diagnostic process, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) is an accurate tool for Actinomyces identification.