Prosthetic valve endocarditis due to non-toxigenic Corynebacterium diphtheriae: A case report.
Ahmed Fakhfakh, Sana Ferjani, Lamia Kanzari et al.
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Case in brief
A 61-year-old woman with a mechanical mitral valve on chronic acenocoumarol presented with fever, malaise, and abdominal pain. Imaging showed splenic infarctions and vegetations on the prosthetic valve; blood cultures grew Corynebacterium diphtheriae. Mass spectrometry identified the organism, and whole-genome sequencing confirmed a non-toxigenic strain lacking the tox gene. Cerebral angiography showed right internal carotid artery occlusion without initial parenchymal lesions. Despite intravenous vancomycin and supportive care, she developed coma and hemodynamic and respiratory failure; imaging showed massive intracerebral hemorrhage with intraventricular extension and herniation. She died.
What made this case unusual
The infection was caused by non-toxigenic C. diphtheriae, yet was associated with prosthetic-valve infection, systemic embolization, and fatal intracranial hemorrhage.
Diagnostic / clinical pearl
C. diphtheriae recovered from blood in a patient with prosthetic-valve endocarditis warrants prompt identification and genomic characterization; absence of the tox gene does not exclude severe invasive disease.
Why it matters
The case illustrates the difficult balance around anticoagulation in mechanical-valve endocarditis complicated by embolic and hemorrhagic neurological events.