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C. acnes Vascular Graft Infection — SCE Infectious Diseases MCQ

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ModerateHealthcare-Associated InfectionsC. acnes Vascular Graft InfectionSCE Infectious Diseases

A 55-year-old man with an aortic root replacement develops late prosthetic graft infection 3 years after surgery. CT shows peri-graft fluid collection. Blood cultures grow Cutibacterium acnes after 12 days of incubation. What is the significance of this slow-growing organism in this context?

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Correct answer: D — C. acnes is a genuine pathogen in prosthetic cardiovascular graft infections — its isolation after prolonged culture from a clinically relevant site should NEVER be dismissed as contamination

E. acnes is increasingly recognised as a cause of prosthetic cardiovascular graft infections, prosthetic valve endocarditis, and PJI. Its slow growth (requiring 7–14+ days of culture) means it is frequently missed by standard 5-day automated blood culture systems. In the context of prosthetic material with compatible clinical features, C. acnes isolation should be considered pathogenic. Treatment requires prolonged IV Benzylpenicillin/Amoxicillin (C. acnes is penicillin-susceptible) for 6+ weeks. Surgical graft replacement may be needed.

Reference: ESC 2023 – Vascular graft infection; BSAC 2023 – C. acnes