Staphylococcus lugdunensis Endocarditis: Lower Mortality in the Contemporary Era?

BACKGROUND: Staphylococcus lugdunensis is a virulent coagulase-negative Staphylococcus that is a rare cause of infective endocarditis (IE) associated with high mortality. A linear growth of IE has occurred over the past several years in Saskatchewan, with overlapping epidemics of human immunodeficiency virus (HIV)/hepatitis C virus driven by injection drug use (IDU). We hypothesized that given the unique challenges faced by our population with IDU and inequitable healthcare access, our cases of S. lugdunensis IE might differ from those in the published literature. METHODS: We retrospectively reviewed the cases of S. lugdunensis endocarditis admitted at our tertiary care hospitals in Saskatoon over a 6-year period and analyzed their baseline characteristics, antimicrobial susceptibility data, management, and outcome data, where available, for each patient. RESULTS: Of the 24 blood cultures positive for S. lugdunensis, as identified by our laboratory, we verified 6 cases of definite IE, and 2 cases of probable IE, applying the modified Duke’s criteria. A total of 5 of 8 cases involved native valves, with only 1 infection of the bioprosthetic mitral valve, seen in patient with IDU. A total of 5 of 8 cases involved the left-sided valves, with 1 of 8 involving the tricuspid valve. Only 1 death was recorded. CONCLUSIONS: The male predominance and primarily left-sided valve infection we noted in our review were similar to results in the published literature. We noted a lower rate of surgical intervention and mortality than previously observed, which merits further study. We did not find coinfection with HIV and/or hepatitis C virus as an epidemiologic risk factor, likely owing to the low rate of IDU in our study.