Distribution of streptococcal groups causing infective endocarditis: a descriptive study

The purpose of this study was to describe the distribution of streptococci causing infective endocarditis (IE). A total of 296 patients with definite IE admitted from July 2007 to December 2014 were identified, with microbial identification done by a combination of blood culture, valve culture, and valve polymerase chain reaction (PCR). The overall distribution of streptococci was 76% viridans (n = 224), 17% pyogenic (50), 6% nutritionally variant (17), and 2% anaerobic (5). Sixty-three (21%) viridans group streptococci were not identified further. The distribution of the remaining 161 viridans group streptococci was Streptococcus mitis group 61%, S. bovis group 15%, S. mutans group 13%, S. anginosus group 9%, and S. salivarius group 1%. Of the 50 pyogenic streptococci, 78% were S. agalactiae and 16% were S. dysgalactiae. PCR was significantly more sensitive than culture in identifying streptococci in excised heart valves. •Viridans group streptococci account for three-fourths of all cases of streptococcal endocarditis, 60% of these being mitis group streptococci.•Pyogenic streptococci are the cause in almost one-fifth of streptococcal endocarditis, with almost 80% of these being S. agalactiae.•PCR is significantly more sensitive than culture in identifying streptococci in heart valves.