2019 Volume 68 Issue 2 Pages 364-369
We herein report a case of infectious endocarditis in which Abiotrophia defectiva infection was detected by a blood culture test. The patient was a woman in her twenties, who visited a local physician due to recurring fever and cough. Pneumonia was suspected owing to an increased inflammatory response in a blood test and the presence of infiltrates detected by chest x-ray infiltrates. She was referred to our hospital and she returned home after receiving antibiotics; however, she had an emergency hospitalization due to a positive blood culture test. Echocardiography revealed severe mitral regurgitation with verrucous vegetation, and she was diagnosed as having infectious endocarditis. She received an emergent mitral valve replacement, and treatment with daptomycin and meropenem was started. Gram-positive coccobacilli were detected in her blood culture and streptococci were initially suspected as the infecting organisms. Nonetheless, nutritionally variant streptococci (NVS) were also suspected because no bacterial growth was observed in a subculture on sheep blood agar; therefore, infectious endocarditis was diagnosed. Bacterial colonies indicating α hemolysis were detected in an anaerobic subculture on Brucella HK agar. A. defectiva was identified using an automated microbial identification and antibiotic susceptibility testing system (Vitek2). Taken together, endocarditis caused by A. defectiva was finally diagnosed because it was detected in cultures of vegetation and oral bacteria. NVS are clinically important. Nonetheless, NVS do not grow in usual culture medium. Therefore, it is important to remain aware of the features of NVS as well as the culture medium being used at a particular lab.
