Streptococci are gram-positive bacteria. Among the beta-hemolytic streptococci, Streptococcus pyogenes (Group A streptococci, GAS) and Streptococcus agalactiae (Group B streptococci, GBS) are major human pathogens. GAS causes over 600 million cases of infections each year, ranging from mild pharyngitis to severe streptococcal toxic shock-like syndrome (STSS), and GBS causes neonatal invasive infections including sepsis, pneumonia, and meningitis.
