Case report: Infective endocarditis caused by Streptococcus sinensis: The first case in mainland China and literature review

Abstract

Streptococcus sinensis was originally described as a causative agent for infective endocarditis in three Chinese patients from Hong Kong in 2002. Subsequently, several cases were reported outside Hong Kong, indicating that it is an emerging pathogen worldwide. We isolated a closely related strain in a young patient diagnosed with infective endocarditis in mainland China. In this paper, we reviewed the course of infection and provided a comprehensive comparison of its clinical characteristics with the reported cases.

Keywords: 16S rRNA sequence; Streptococcus sinensis; case report; emerging pathogen; infective endocarditis.

Figure 1

The TEE results of the mitral valve and WBC levels. TTE revealed (A) flocculent hypoechoic vegetations of the aortic valve (the red arrow) and (B) a moderate regurgitation bundle on the left ventricular outflow tract side during diastole of the aortic valve. (C) The histochemical analysis of the valve tissue revealed local myxoid and hyaline degeneration, missing endothelial cells, necrotic attached substances (the blue arrow), and neutrophil aggregation (the black arrows). Scale bars approximate 50 μm in length. The (D) WBC count and cell proportions and (E) CRP throughout the course. TTE, transthoracic echocardiography; LA, left atrium; LV, left ventricle; RA, right atrium; RVOT, right ventricular outflow tract; AO, aorta; PA, pulmonary artery; WBC, white blood cell; CRP, C-reactive protein.

Figure 2

The timeline of the case presentation. The patient was discharged with a monthly follow-up 26 days after his admission. BT, body temperature; ESR, erythrocyte sedimentation rate; BCs, blood cultures; IE, infective endocarditis; PCT, procalcitonin.

Figure 3

The phylogenetic tree based on the 16S rRNA gene sequences showing the relationship of isolated strain BC1012612 (the black arrow) and members within the genus Streptococcus. The tree was reconstructed by the neighbor-joining method, and Enterococcus faecalis JCM5803T was used as an outgroup. Bootstrap values (>50%) based on 1,000 replicates are shown at branch nodes. T, type strain.