Subacute prosthetic aortic endocarditis caused by Actinotignum schaalii: a rare but destructive pathogen - case report and literature review.

Abstract

<h4>Background</h4>Actinotignum schaalii is an emerging urogenital pathogen rarely reported as a cause of endocarditis.<h4>Case presentation</h4>A 54-year-old man developed recurrent embolic strokes seven and eight years post-Bentall procedure with mechanical aortic valve. Blood cultures grew Gram-positive bacilli, initially misidentified as Corynebacterium spp., later confirmed as Actinotignum schaalii. Cardiac CT revealed a 12 mm × 15 mm × 20 mm perivalvular abscess fistulizing into the sinus of Valsalva and prosthetic graft. 18 F-FDG PET/CT confirmed intense hypermetabolism around the prosthesis. Despite targeted amoxicillin therapy, intraoperative exploration revealed complete Bentall conduit dehiscence from extensive aorto-mitral trigone destruction. Reconstruction was deemed unfeasible, and the patient died following multidisciplinary decision to limit interventions. No urological source was identified.<h4>Conclusions</h4>Actinotignum schaalii can cause indolent prosthetic valve endocarditis with devastating perivalvular complications. Prolonged blood culture incubation is crucial for early diagnosis in patients with prosthetic material and unexplained embolic events.<h4>Clinical trial</h4>Not applicable.