A case report of Gemella sanguinis isolated from blood cultures of a patient with mitral valve prolapse

Gemella sanguinis is a gram-positive, facultatively anaerobic coccus bacterium that has rarely been reported as a cause of infective endocarditis. A 41-year-old male patient with mitral valve prolapse visited the outpatient clinic presenting with fever. Transthoracic echocardiography and transesophageal echocardiography revealed myxomatous change and vegetation of the mitral valve. We isolated G. sanguinis from the patient’s blood, cultured it in both aerobic and anaerobic blood culture bottles, and identified it using matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS; bioMérieux, France) and 16s rRNA sequencing. The isolated G. sanguinis was highly susceptible to penicillin and vancomycin and intermediately susceptible to erythromycin, clindamycin, and levofloxacin. Following the American Heart Association recommendations, this highly penicillin-sensitive isolate was eradicated with ceftriaxone and gentamicin, and the patient recovered and was discharged. To the best of our knowledge, this is the first reported case in Korea where G. sanguinis, the causative agent of endocarditis, was identified using MALDI-TOF MS and 16s rRNA sequencing and was treated with only antibiotics and without surgical valve replacement.