Actinomyces graevenitzii Detected in a Case of Endobronchial Actinomycosis Caused by Foreign Body Aspiration: A Case Report

Pulmonary actinomycosis is a chronic respiratory infection caused by Actinomyces. Actinomyces graevenitzii is a rare species of Actinomyces with rare cases of infections. Herein, we report a case of endobronchial actinomycosis due to foreign-body aspiration in which A. graevenitzii was identified. The patient was a 48-year-old woman with a prior history of childhood asthma. She presented with a three-month history of hemoptysis, green sputum, and cough. Plain computed tomography of the chest revealed an elongated foreign body at the left inferior lobar bronchus, with infiltrative opacities extending from the foreign body to the peripheral regions and bronchial mucus plugs. Further inquiry revealed that she had choked while eating fish five years prior, followed by a persistent dry cough. She attributed this to her childhood asthma history. The foreign body retrieved during bronchoscopy showed histological features consistent with those of a bone. Thin, filamentous gram-positive bacilli were detected in the endobronchial lavage fluid and identified as A. graevenitzii by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Symptoms resolved after bronchoscopy. These findings indicate that A. graevenitzii can cause endobronchial actinomycosis following foreign-body aspiration and support the value of MALDI-TOF/MS for identifying the causative organism in endobronchial actinomycosis. The widespread adoption of MALDI-TOF/MS will facilitate the identification of previously difficult-to-identify Actinomyces, further improving understanding of their clinical characteristics and potentially informing treatment strategies.