Corynebacterium propinquum as the first cause of infective endocarditis in childhood.

We here present a 7-year-old girl with ventricular septum defect and ventriculoatrial communication, who developed infective endocarditis (IE) due to Corynebacterium propinquum in the tricuspid valve. The patient was admitted because of an 8-day history of fever. Transthoracic echocardiogram showed non-pedunculated vegetation on the septal leaflet of the tricuspid valve. Gram-positive coryneform bacteria grew from three consecutive sets of blood cultures taken on admission. C. propinquum was confirmed by 3 microbiological approaches; (i) biochemical testing using API Coryne panels, (ii) a sequence-based method using the 16S rRNA gene and partial rpoB sequencing, and (iii) matrix-assisted laser desorption ionization-time of flight mass spectrometry. The isolates were susceptible to a wide variety of β-lactams and vancomycin. The patient was successfully treated with antimicrobial agents without surgical intervention. There have only been available of clinical details of two adult cases of invasive C. propinquum infections; one of which was presented as IE, and the other was pleuritis in a patient with lung cancer. To the best of our knowledge, this is the first report to describe C. propinquum as a cause of IE as well as that of invasive infections in a pediatric population. Multiple methods that reliably differentiated related species helped us to establish this rare organism. Our report expanded the clinical spectrum of C. propinquum infections.