A woman with infectious endocarditis caused by Abiotrophia defectiva.

A 74-year-old woman with recurrent fever and multiple joint pain was admitted to Hokkaido University Hospital. Trans-esophageal echocardiogram revealed bacterial vegetation and destruction of the aortic valve. Although few bacteria grew in regular blood agar, Gram-positive coccobacillus was specifically grown in chocolate blood agar and Brucella agar, and it was identified to be Abiotrophia defectiva. Infectious endocarditis caused by Abiotrophia defectiva was diagnosed, she was treated with diuretics, penicillin G and gentamicin, and she immediately improved. Infectious diseases caused by Abiotrophia defectiva are extremely rare, and identification of this pathogen is important, as its bacterial characteristics require proper attention.