Pasteurella dagmatis prosthetic valve endocarditis with suspected mycotic aortic aneurysm: a case report

We report a case of prosthetic valve infective endocarditis caused by Pasteurella dagmatis in a 79-year-old man with a mechanical aortic valve and a known ascending aortic aneurysm. He presented with fever and malaise, and blood cultures grew P. dagmatis. Transoesophageal echocardiography demonstrated a prosthetic valve vegetation with a suspected aortic root abscess, while computed tomography confirmed a large ascending aortic aneurysm. The clinical course was complicated by conduction disturbances requiring permanent pacemaker implantation. The patient underwent urgent surgical intervention and made a good recovery, being discharged in a stable condition, but with persistent atrial fibrillation. This case highlights the rarity of P. dagmatis as a cause of IE and its potential for invasive complications. Although histopathological confirmation was not obtained, the infection may have contributed to progression of the pre-existing aneurysm, raising the possibility of a superimposed mycotic aneurysm.