Bacteria under Microscope

Streptococcus pyogenes
Group A streptococcus

Streptococcus pyogenes   
                         microscopy, gram-positive cocci


Gram-positive cocci


Microscopic appearance:

Cocci in clusters, short chains, diplococci and single cocci


Clinical significance:

  • It is an infrequent, but usually pathogenic, part of the skin flora.
  • S. pyogenes is the cause of many important human diseases, ranging from mild superficial skin infections to life-threatening systemic diseases.
  • pharyngitis ("strep throat")
  • localized skin infection ("impetigo")
  • Erysipelas and cellulitis
  • Necrotizing fasciitis
  • Scarlet fever
  • Streptococcal toxic shock syndrome
  • Rheumatic fever
  • Acute postinfectious glomerulonephritis
    Text: Wikipedia

Colony morphology:

Streptococcus pyogenes identification
A Beta-hemolytic colonies of Streptococcus pyogenes on sheep blood agar. Cultivation 24 hours, aerobic atmosphere, 37°C.  
B Colonies of Streptococcus pyogenes (Group A streptococcus, abbreviated GABHS) on sheep blood agar. Beta-hemolysis around colonies. Cultivation 24 hours in an aerobic atmosphere, 37°C.  
C S.pyogenes on Columbia agar with 5% defibrinated sheep blood, 24 hours in an aerobic atmosphere, 37°C. Colonies are surroundend by a wide zone of beta-hemolysis.