Rare case of Histoplasma capsulatum endocarditis in a patient with a prosthetic valve

BACKGROUND: Diagnosis of fungal endocarditis can be challenging, especially among cases with negative blood culture results. Of fungal endocarditis cases, Histoplasma capsulatum constitutes an even smaller proportion with ∼58 prior cases reported. Due to the rarity of histoplasmosis endocarditis and thus limited data, there is no current diagnostic guideline for testing within culture negative infective endocarditis. CASE SUMMARY: Our patient was a 58-year-old female presenting with worsening dyspnoea, hypotension, and near-syncope. In this case report, we depict the clinical presentation and diagnosis of H. capsulatum endocarditis in a female patient with a prosthetic aortic valve and negative blood cultures. We further demonstrate the rising risk of fungal endocarditis with use of external devices. DISCUSSION: Despite the rarity of fungal endocarditis, there has been a recent upward trend in infections given the rising use of external devices, greater number of immunocompromised patients, and rising rates of intravenous drug use. Recently, more cases of fungal endocarditis have been occurring in patients with prosthetic valves compared to native. Although H. capsulatum constitutes a smaller proportion of fungal endocarditis cases, patients with appropriate risk factors and those who have been exposed to at-risk areas such as the Ohio and Mississippi River valleys, may benefit from further evaluation.