Finding of Anaerococcus hydrogenalis in blood using cell-free DNA technique in a patient with infective endocarditis.

Introduction: The annual incidence of infective endocarditis (IE) is 3-9 cases per 100000 in developed countries and most cases are due to staphylococci and streptococci. IE due to Gram-positive anaerobic cocci (GPAC) is very rare.

Case report: We present a case of a 38-year-old female with Anaerococcus hydrogenalis bacteremia and infective endocarditis of the native mitral valve. She presented with fever, chills, and abdominal pain. A computed tomographic scan of the abdomen showed splenic abscesses. Blood cultures and broad-range PCR from the splenic abscess sample were negative. Transthoracic echocardiography showed a mobile filamentous structure on the atrial side of the anterior mitral leaflet which was suggestive for infective endocarditis. Karius test (cell-free microbial DNA testing) showed Gram-positive anaerobic cocci Anaerococcus hydrogenalis. She was successfully treated with antibiotics.

Conclusions: In cases of infection with fastidious organisms like GPACs, the use of next-generation sequencing (NGS) can allow the correct identification of culprit pathogens and streamlined treatment.