The Deadly Contaminant: A Case of Staphylococcus lugdunensis Endocarditis

The incidence of infective endocarditis (IE) has been on the rise since it was first reported a century ago, and the associated mortality remains unchanged despite advances in medical and surgical management. To diagnose IE, the modified Duke criteria are used, which rely on isolating the causative organism. However, this can be challenging if the micro-organism is considered a contaminant. Staphylococcus lugdunensis (SL) is one such organism. In this case, an elderly female presented with intermittent chest pain, palpitation, and diaphoresis, for which she underwent left heart catheterization. Her hospital course was complicated by persistent fever and night sweats, leading to blood cultures isolating methicillin sensitivity. It was initially reported as a contaminant. However, an extensive workup was unremarkable, and a transthoracic echocardiogram was done, which revealed tricuspid vegetations with moderate regurgitation. The patient was treated with cefazolin, repeat cardiac imaging at the end of treatment revealed no vegetation, and the patient remained asymptomatic. Despite being associated with fulminant IE with higher mortality than Staphylococcus aureus (S. aureus), which requires surgical management in most cases, SL is still often reported as a contaminant. Isolation of SL should warrant further investigation beyond mere contaminants, and prompt treatment should be initiated in the appropriate clinical scenario to avoid poor outcomes.