Propionibacterium acnesas a cause of lung abscess in a cardiac transplant recipient

A 29-year-old man was admitted with fevers, cough, left-sided chest pain and lethargy for 1 week. He had a cardiac transplant 10 years prior and was on immunosuppressive drugs. He was found to have a pulmonary lesion and went on to develop a lung abscess. Propionibacterium acnes was identified on matrix-assisted laser desorption ionisation mass spectrometry-time of flight and 16s rRNA gene sequencing after drainage. He was curatively treated with co-trimoxazole and co-amoxiclav. He divulged a longstanding history of seborrhoeic dermatitis with frequent flares leading to large volumes of squames collecting on his bed sheets. We hypothesise this was a possible route of entry: inhalation of the Propionibacterium. This case highlights how a common commensal bacterium, P. acnes, was able to cause pathology in an immunosuppressed patient. This is the only case of a patient with transplantation developing a P. acnes pulmonary infection and the only case of P. acnes causing these clinical features to be reported in the literature.