Smoldering Threat: Pacemaker-associated Infective Endocarditis Caused by Cutibacterium Acnes in a Young Patient with Congenital AV-Block

All articles of this category (opens in new window) Background: Cardiac implantable electronic device (CIED) infections are increasingly recognized as a serious complication, particularly in younger patients with congenital heart disease. While Staphylococcus species are the most common pathogens, low-virulence organisms such as Cutibacterium acnes are emerging in device-related endocarditis. Their indolent course and subtle clinical presentation often delay diagnosis and treatment, posing a challenge for clinicians. Methods: We present the case of a 29-year-old male with congenital third-degree atrioventricular block and an endocardial dual-chamber pacemaker. He was admitted with persistent fever, fatigue, and a large left-sided pleural effusion. Initial blood cultures were negative. Transesophageal echocardiography revealed vegetations adherent to the pacemaker leads and severe tricuspid regurgitation. Cultures from extracted device components later grew C. acnes, confirming the diagnosis. Results: The patient underwent complete device removal, removal of vegetations from the tricuspid valve, and tricuspid valve repair and received 6 weeks of targeted intravenous antibiotic therapy. Clinical symptoms resolved rapidly following lead extraction. Conclusion: This case illustrates the diagnostic challenges posed by C. acnes, which may be dismissed as a contaminant due to its slow growth and skin commensal status. However, its pathogenic role in CIED infections is increasingly recognized, especially in patients with long-standing implants and nonspecific symptoms. Early imaging and microbiological evaluation, including prolonged culture incubation, are essential for timely diagnosis. Clinicians should maintain a high index of suspicion for C. acnes in device-related infections, particularly when standard cultures are negative and symptoms persist. Beyond individual cases, this highlights a broader need for increased awareness of low-virulence organisms in the context of implantable devices. Diagnostic algorithms may need to evolve to incorporate extended culture protocols and molecular techniques. Furthermore, interdisciplinary collaboration between cardiology, infectious disease, and microbiology teams is crucial for optimizing outcomes in such complex presentations. Publication History Article published online: 17 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany