Pulmonary actinomycosis with polymicrobial co-infection presenting as pulmonary abscess：a case report

Background: Pulmonary actinomycosis is very rare. It is often misdiagnosed as lung cancer, tuberculosis, pulmonary aspergillosis or pulmonary abscess. Predisposing factors are immunosuppressive conditions, poor oral hygiene and chronic lung disease. Co-infection with different strains of actinomycetes, aspergillus and bacteria is rarely reported, which is a major cause of treatment failure. Case presentation： We reported a case of 63-year old woman with 3-month history of cough, expectoration and occasional hemoptysis. Pulmonary actinomycosis with polymicrobial co-infection including actinomyces mucous, actinomyces graevenitzii, aspergillus, klebsiella pneumoniae and streptococcus constellations in left inferior lobe was confirmed by etiological culture. Combined antibiotic therapy and bronchoalveolar lavage were administrated successfully. The clinical symptoms and radiologic abnormalities had improved significantly. Conclusions: : Pulmonary actinomycosis is often misdiagnosed because of the nonspecific clinical manifestations and laboratory tests.Bronchoscopy plays a key role in the diagnostic and therapeutic pathways. Co-infection make the treatment more difficult. This case improves our understanding of the diagnosis and comprehensive therapeutic strategies for pulmonary actinomycosis with polymicrobial co-infection in the elderly.