Abstract
We encountered a case of infective endocarditis (IE) caused by Gemella sanguinis, which has not yet been reported in Japan. A 57-year-old woman consulted a local doctor because of recurring fever and respiratory discomfort and palpitation during exercise since early May 2012. Suspected of having IE, she was admitted to the cardiovascular medicine department of our hospital for extensive investigation and treatment. Examination of bacteria from a blood culture collected on the day of admission using a commercial biochemical identification kit led to the identification of Gemella haemolysans, while acid productions from mannitol and sorbitol and alanyl-phenylalanine-proline arylamidase activity showed anomalies. Analysis of the 16S rRNA nucleotide sequence and mass spectrometry led to the identification of G. sanguinis, which was different from the result of the biochemical identification. Although bacteria were not isolated from the surgically excised vegetation in the aortic valve, probably owing to the antimicrobial chemotherapy performed, analysis of the 16S rRNA nucleotide sequence of bacterial DNA from the vegetation led to the identification of G. sanguinis, which was consistent with the result of the blood culture test. The patient was continuously given penicillin G and gentamycin since her admission, and after a valve replacement operation, she showed improvement of symptoms and left the hospital in remission. While some cases of IE caused by G. sanguinis have been reported abroad, none has been reported in Japan. This species of bacteria is difficult to determine and is not listed in the databases of identification kits. Therefore, when Gemella is identified with an identification kit, further examination by genetic analysis and mass spectrometry should be considered, depending on the case. Drug susceptibility tests are also important because some cases of drug resistance have been reported.
