Staphylococcus caprae native mitral valve infective endocarditis

T'Ng Choong Kwok,Oliver Koch,Ewan Olson,Jennifer Poyner,Peter Henriksen

doi:10.1099/jmmcr.0.005065

Abstract

Introduction:Staphylococcus caprae is a rare cause of infective endocarditis. Here, we report a case involving the native mitral valve in the absence of an implantable cardiac electronic device.Case presentation:A 76-year-old man presented with a 2 week history of confusion and pyrexia. His past medical history included an open reduction and internal fixation of a humeral fracture 17 years previously, which remained non-united despite further revision 4 years later. There was no history of immunocompromise or farm-animal contact. Two sets of blood culture bottles, more than 12 h apart, were positive for S. caprae. Trans-thoracic echocardiography revealed a 1×1.2 cm vegetation on the mitral valve, with moderate mitral regurgitation. Due to ongoing confusion, he had a magnetic resonance imaging brain scan, which showed a subacute small vessel infarct consistent with a thromboembolic source. A humeral SPECT-CT (single-photon emission computerized tomography-computerized tomography) scan showed no clear evidence of acute osteomyelitis. Surgical vegetectomy and mitral-valve repair were considered to reduce the risk of further systemic embolism and progressive valve infection. However, the potential risks of surgery to this patient led to a decision to pursue a cure with antibiotic therapy alone. He remained well 3 months after discharge, with repeat echocardiography demonstrating a reduction in the size of the vegetation (0.9 cm).Conclusion:Management of this infection was challenging due to its rarity and its unclear progression, complicated by the dilemma surrounding surgical intervention in a patient with a complex medical background.

Highlights

Staphylococcus caprae is a rare cause of infective endocarditis
Native valve endocarditis is rare in its own right, but much rarer when caused by coagulase-negative staphylococci (7.8 %) (Chu et al, 2008) in the absence of an implantable cardiac electronic device (ICED) and history of intravenous (i.v.) drug use
Staphylococcus caprae is a coagulase-negative staphylococcus originally isolated in goats, but increasingly identified in nosocomial and community-acquired infections, especially human bone and joint infections (Shuttleworth et al, 1997; Seng et al, 2014)

Summary

Introduction

Native valve endocarditis is rare in its own right, but much rarer when caused by coagulase-negative staphylococci (7.8 %) (Chu et al, 2008) in the absence of an implantable cardiac electronic device (ICED) and history of intravenous (i.v.) drug use. The possibility or removing metalwork from his humerus was considered, but the risks of fracture site instability, non-union and subsequent loss of function in his arm were considered too great His continued improvement on antibiotic therapy, together with uncertainty surrounding occult infection in his left humeral metalwork, led to a decision to pursue antibiotic therapy. He was managed conservatively with i.v. flucloxacillin, and a repeat trans-thoracic echocardiogram post-completion of i.v. antibiotics identified a reduction in vegetation size to 0.9Â0.7 cm. He remained well and apyrexial at a 3 month clinic follow-up, with no further episodes of embolization

Conclusion

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Discussion