Direct Amplification and Sequencing of the 16S Ribosomal RNA Gene in Heart Valve Tissue to Identify the Etiology of Corynebacterium diphtheriae Endocarditis

Abstract

We report the diagnosis of Corynebacterium diphtheriae endocarditis based exclusively on direct 16s ribosomal RNA (rRNA) gene PCR amplification and sequencing in a middle-aged male with a history of substance abuse and psychiatric disease. He presented with hypotension and acute kidney injury and was admitted for medical management. Subsequent to admission, he developed fevers and altered mental status. Blood cultures were negative and cerebrospinal fluid culture grew 1+ Staphylococcus warneri, which was believed to be a contaminant. Transesophageal echocardiography revealed a subvalular vegetation below the mitral valve. The mitral valve was resected and replaced with a bioprosthesis. The specimen was split for histopathology, conventional smears and cultures, and 16S rRNA gene PCR followed by sequencing. The only methodology that yielded the etiologic agent was direct PCR and sequencing.