Brewer’s Yeast as a cause of infective endocarditis

Background: Molecular tests are increasingly used in culture negative endocarditis and may be helpful adjuncts to diagnosis; here we report the case of Saccharomyces cerevisiae mitral valve endocarditis in an immunocompetent patient.

Case History: A previously well 63 year old man presented with a ten day history of fever, nights sweats and progressive shortness of breath. On arrival, he was in acute respiratory distress, in pulmonary oedema and had a pansystolic murmur. A transoesophageal echocardiogram showed severe mitral regurgitation and a mass on the posterior leaflet of the mitral valve. He was treated for a presumed native valve endocarditis with Amoxicillin, Flucloxacillin and Gentamicin. He had a minimally invasive mitral valve repair; a vegetation was noted. All initial cultures and serologies were negative. He improved and was discharged on ceftriaxone and doxycycline on OPAT. Results three weeks post-surgery showed a Beta D Glucan of >500pg/mL (cut off 80) and an 18S PCR on the valve positive for Saccharomyces cerevisiae. No histology was available from the vegetation and fungal cultures were negative. He was much improved at that point and received 6 weeks of voriconazole to treat invasive infection; his Beta D Glucan fell to less than 30 and he was well on follow-up.

Conclusion: Saccharomyces cerevisae is an unusual cause of an endocarditis in an immunocompetent patient. This case illustrates the importance of considering non-bacterial causes of endocarditis in such cases and the utility of molecular diagnostics as adjuncts to traditional culture techniques.