An Unusual Culprit: Staphylococcus capitis Native Mitral Valve Endocarditis Following Scalp Surgery.

Staphylococcus capitis is a coagulase-negative Staphylococcus (CoNS) that colonizes the skin, particularly the scalp, and is often dismissed as a blood culture contaminant in the absence of prosthetic material. Reports of invasive adult infections, particularly native valve endocarditis (NVE), are rare. We describe the case of a man in his 50s, previously healthy and with no known cardiac pathology, who presented with a three-week history of night sweats, myalgia, chest discomfort, and severe neck pain. Clinical examination revealed a pansystolic murmur, and five sets of blood cultures were positive for S. capitis. Echocardiography demonstrated large mitral valve vegetations with leaflet perforation and severe regurgitation. MRI revealed cervical discitis. The clinical course was complicated by antibiotic-associated hepatic cholestasis, rash, and thrombocytopenia, necessitating multiple antimicrobial switches. Ultimately, the patient underwent successful mechanical mitral valve replacement and completed a prolonged antibiotic course. Although S. capitis is frequently dismissed as a contaminant, this case highlights its potential to cause severe invasive disease, including NVE and discitis, even in immunocompetent adults without prosthetic devices or comorbidities. The unusual flucloxacillin susceptibility of the isolate further underscores the variability of antimicrobial resistance patterns in S. capitis. Clinicians should maintain a high index of suspicion when S. capitis is repeatedly isolated from blood cultures, and prompt echocardiography is essential to prevent diagnostic delay and adverse outcomes.