Small colony variant E. faecalis as cause for bioprosthetic heart valve endocarditis

We describe a patient with an endocarditis of a biological heart valve prosthesis caused by a small colony variant Enterococcus faecalis . Human infections caused by a small colony variant (SCV) E. faecalis are rare and only five patients have been described in literature, four of which involved endocarditis. The SCV E. faecalis isolated from blood culture bottles resembled streptococci by Gram staining and exhibited atypical growth on standard agar plates with small white colonies after 48 hours of incubation. This case describes a rare case of E. faecalis associated with endocarditis with small colony growth, which can be difficult to recognize in medical microbiological laboratories using conventional techniques. These difficulties with identification can delay initiation of adequate treatment and may affect patient outcome.