BACKGROUND: Infective endocarditis is prevalent worldwide and the modified Duke criteria have been used universally to diagnose this condition. However, making the correct diagnosis is rather difficult because the clinical presentation and findings of blood tests are non-specific.

CASE REPORT: A 70-year-old female complaining of dyspnea for 5 days with acute mitral regurgitation was transferred to our hospital. She had acute heart and respiratory failure and disseminated intravascular coagulation. Although infective endocarditis was suspected, repeated blood cultures and transesophageal echocardiography could not reveal any findings of infective endocarditis. Because the etiology of her condition was not determined by various examinations, mitral annuloplasty was required to treat her mitral regurgitation, and was performed for definitive diagnosis and treatment revealing the presence of vegetation on the mitral valve. Enterococcus faecalis was detected by cultures of the mitral valve and blood after the surgery.

CONCLUSIONS: It can be very difficult to diagnose infective endocarditis correctly, especially when a case fails to fulfill the modified Duke criteria. In such a case, only cardiac surgery might enable us to make an accurate diagnosis and save a patient’s life.

Keywords: Disseminated Intravascular Coagulation, Endocarditis, Enterococcus faecalis, Mitral Valve Annuloplasty, Mitral Valve Insufficiency