An Uncommon Culprit: Leclercia Adecarboxylata Causing Native Mitral Valve Infective Endocarditis in an Immunocompromised Host

Leclercia adecarboxylata is an uncommon pathogen causing infective endocarditis, with limited number of infections reported in the literature. A literature review showed only three cases of infective endocarditis caused by L. adecarboxylata had been reported up to 2022, highlighting the organism’s rarity as a cause of endocarditis in clinical practice. We report a unique case of native mitral valve infective endocarditis in a 69-year-old woman with long-standing diabetes mellitus and hypertrophic non-obstructive cardiomyopathy. Although initial blood cultures yielded methicillin-sensitive Staphylococcus epidermidis, definitive diagnosis was established intraoperatively when purulent material and excised mitral valve tissue grew pan-sensitive Leclercia adecarboxylata, fulfilling a major criterion of the 2023 Duke–ISCVID infective endocarditis guidelines. This case illustrates the emerging role of uncommon pathogens in infective endocarditis and reinforces the diagnostic significance of valve tissue cultures and intraoperative evidence in modern clinical practice.