All are true about streptococcus except :

“Mucoid colonies are due to production of capsule of hyaluronic acid not due to M protein.” Harrison 17/e, p 882 Growth characteristic of Strep. pyogenes : On blood agar virulent stains forms matt or mucoid colonies while avirulent form glossy colonies. M, T, R are proteins found on outer part of cell wall and forms the basis of Griffith classification. – M protein - Acts as virulence factor and antibody against it are protective. – T and R protein - No relation to virulence Streptococci (Except enterococci) are usually susceptible to penicillin so option “d” is not completely wrong. As option “a” is completely wrong, that would be the answer.