Sign Up for a Free Account

This is an image preview.
Start a Free Account
to view the full image.

  • Nearly 3,000 illustrations, including video clips of neurologic disorders.

  • Every article is reviewed by our esteemed Editorial Board for accuracy and currency.

  • Full spectrum of neurology in 1,200 comprehensive articles.

  • Listen to MedLink on the go with Audio versions of each article.

Culture of Streptococcus pyogenes (Group A beta-hemolytic Streptococcus) bacteria on soy agar containing 5% defibrinated sheep's blood

Petri dish with Streptococcus pyogenes-inoculated trypticase soy agar containing 5% defibrinated sheep's blood that had been streaked and stabbed with a wire loop, which had been dipped into primary culture medium. The blood agar plate (BAP) was incubated in a normal atmosphere at 35°C for 24 hours. In this case, the culture dish grew colonies of Gram-positive, Group A beta-hemolytic streptococci ("GAS") bacteria. The characteristic color changes, including a light-colored halo surrounding each colony in which the red blood cells in the blood agar medium had been destroyed, or hemolyzed, indicated that these bacteria were indeed beta-hemolytic in nature. (Courtesy of the Centers for Disease Control and Prevention Public Health Image Library. Image 8170. Photograph by Dr. Richard R Facklam, CDC, 1977. Public domain.)

Related Article

Associated Disorders

  • Arthritis
  • Athetosis
  • Carditis
  • Chorea gravidarum
  • Obsessive-compulsive behavior
  • Rheumatic fever
  • Streptococcal pharyngitis