Gemella spp. Prosthetic Valve Endocarditis Following Prior Multivalvular Infective Endocarditis in a TAVI Recipient

Abstract

Background : Infective endocarditis is a serious complication in prosthetic heart valves, including after transcatheter aortic valve implantation (TAVI). Although Staphylococcus aureus, streptococci and enterococci predominate, uncommon fastidious organisms may occur. Gemella spp. are rare invasive pathogens and have only exceptionally been reported in prosthetic valve endocarditis. We report an unusual case in a TAVI recipient with previous multivalvular infective endocarditis. Case Report : A 73-year-old man with previous TAVI, permanent pacemaker implantation, chronic atrial fibrillation and prior multivalvular infective endocarditis was admitted with suspected recurrence. The initial presentation was non-specific and later complicated by hypothermia and hyperlactataemia, prompting empirical broad-spectrum antibiotics. Laboratory tests showed normocytic anaemia and mild inflammation, while repeated in-hospital blood cultures remained negative. Initial transthoracic and transoesophageal echocardiography were inconclusive. FDG-PET/CT demonstrated multifocal hypermetabolic uptake around the aortic prosthesis, strongly suggestive of prosthetic valve infective endocarditis, with partial regression of previously noted mitral inflammatory uptake. Repeat echocardiography revealed a mobile lesion attached to the prosthesis. Brain MRI excluded embolic complications. Delayed pre-admission blood cultures grew Gemella spp. ; the isolate was identified only at genus level. Targeted intravenous amoxicillin therapy was initiated. Conclusion : Gemella infective endocarditis remains exceptionally rare but clinically significant, particularly in prosthetic valve infection. This case highlights the need to consider uncommon fastidious pathogens when suspected infective endocarditis is not confirmed by initial investigations and emphasises the complementary role of FDG-PET/CT in guiding diagnosis and management.