Streptococcus straw green, also known as Streptococcus aureus and Streptococcus haemolyticus A, is a Gram-positive cocci, which is one of the important normal flora of the human body, distributed in the upper respiratory tract, gastrointestinal tract and female genital tract, with the most oral distribution. Recently, the genetically related classification was used to classify the bacteria into more than ten species, among which Streptococcus ligamentosus, Streptococcus haematobium, Streptococcus miller, Streptococcus salivarius and Streptococcus mutans can often lead to the occurrence of various infections. It is still the main causative agent of infective endocarditis.