Case Presentation: A 31-year-old woman with a history of rheumatic heart disease and a murmur presented with two months of intermittent subjective fevers, diffuse malaise and inability to walk. Physical exam revealed a systolic 2/6 murmur heard best at the apex, 3 out of 5 strength with right knee extension and flexion and 3 out of 5 strength with right shoulder abduction. Laboratory studies were significant for a WBC of 13, an ESR of 99 and a CRP of 108. Blood cultures grew Staphylococcus lugdunensis and transthoracic echocardiogram revealed a mobile thickening on the left anterior leaflet. Because of her right sided weakness, CT spine was done revealing a right external iliac artery septic embolus, MRI brain showed septic emboli and evidence of cerebritis and meningitis. Due the MRI findings, CT angiogram of the head was done showing a mycotic aneurysm. Her symptoms slowly improved with nafcillin, but on day 9 of hospitalization, the patient had an episode of transient dysarthria and MRI brain confirmed another septic emoblus. She subsequently underwent urgent surgical mitral valve repair. The patient’s post-operative course was uncomplicated and she was discharged home a week later on 6 weeks of IV nafcillin.
Discussion: Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CoNS) that was first described in 1988 and is most commonly known as a skin colonizer. It is unique among CoNS because the majority of cases are community acquired with an unknown portal of entry and its virulence is similar to Staph Aureus. It causes an aggressive, often fatal native valve infective endocarditis (IE). In one case review of S. lugdunensis IE, researchers found a 42 % mortality rate and more than 30% of patients had septic emboli. This is in comparison to other CoNS IE patients where mortality rates are approximately 20% and septic emboli rates are approximately 5%.
Further differentiating S. lugdunensis from other CoNS IE is the fact that medical treatment with antibiotics may not be sufficient and in one systematic review, medical treatment alone was an independent risk factor for mortality with an odds ratio of 4.79 (1.16-19.78). In most cases reviewed in this study, the patients with better outcomes were those where early cardiac surgery was performed.
Conclusions: We classically think of CoNS infections as being of low virulence but S. lugdunensis is an aggressive cause of native valve IE with high rates of morbidity and mortality. Clinicians should be aggressive in diagnosing and treating patients with CoNS bacteremia and signs of endocarditis because of the risk for virulent bacteria such as S. lugdunensis. They should be especially suspicious of S. lugdunensis when patients have septic emboli and should ask the lab to speciate the CoNS. Further, early cardiac surgery should be considered in patients with S. lugdunensis infective endocarditis given its high risk for complications including death.