Staphylococcus lugdunensis: a rare but destructive cause of coagulase-negative staphylococcus infective endocarditis

Background: Staphylococcus lugdunensis is a coagulase-negative organism that causes a rare but destructive form of infective endocarditis (IE). We sought to evaluate the clinical and echocardiographic profile of S. lugdunensis IE at our institution and compare it to that of Staphylococcus aureus IE.

Methods: Utilizing microbiology isolates, we retrospectively reviewed cases of S. lugdunensis bacteraemia admitted to our institution between 2002 and 2011 and included cases that met the modified Duke's criteria and those with device infection. We used univariate analysis to compare the clinical and echocardiographic features and outcomes of these patients with 76 cases of S. aureus IE.

Results: We identified 15 cases of S. lugdunensis IE (10 native, two prosthetic, three device only), amongst whom five cases had underlying structural valvular heart disease. Echocardiography revealed bulky vegetations in 12, abscesses in three, perforation in four, and valve dehiscence in one case. Overall, 7/12 (58%) of valvular IE involved left-sided valves; six of these underwent successful surgical intervention. S. lugdunensis IE resulted in marked valvular destruction similar to S. aureus IE but was more likely to affect patients with prior structural valvular heart disease (42 vs. 7%, p=0.004).

Conclusions: Unlike other coagulase-negative staphylococci, S. lugdunensis causes a rare but destructive form of IE that can involve structurally normal native valves. Echocardiographic imaging is characterized by bulky vegetations and profound valvular destruction similar to that seen with S. aureus IE, thus isolation of this organism in the blood should not be disregarded as a contaminant. Confirmation of left-sided valvular endocarditis warrants surgical intervention.