File:Group A streptococcus20.jpeg

This 1977 photograph depicted two Petri dishes each filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP). The plate on the left had been stabbed and streaked with an inoculum containing Streptococcus mitis, alpha-hemolytic bacteria, a member of the Viridans group, while the right plate was stabbed with an inoculum containing Group A Streptococcus pyogenes (GAS), a typical beta-hemolytic bacteria. The inoculation was performed using a wire loop, which had been dipped into a primary culture medium. The BAPs were incubated in a carbon dioxide enriched atmosphere at 35oC for 24 hours. There is no magnification of this image.