<prompt> All are medically impoant streptococci exceptStreptococcus pyogenesStreptococcus agalactiaeStreptococcus equisimilusStreptococcus salivarius  <response>: Streptococcus viridans is a miscellany of streptococci, normally resident in the mouth and upper respiratory tract. Based on sugar fermentation, cell wall composition and production of dextrans and levans, they have been classified into: S. mitis S. mutans S. salivarius S. sanguis Reference: Textbook of Microbiology; Anathanarayan and paniker;s; 9th edition; Page no: 218 