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Streptococcus pneumoniae: alpha-hemolysis on blood agar
microscope picture gram-positive diplococci

Streptococcus pneumoniae

Streptococcus pneumoniae cultivated on blood agar aerobically, 5% CO2, overnight. Zones of alpha-hemolysis around colonies.

On blood agar, encapsulated pneumococci produce round, glistening colonies surrounded by a zone of alpha-hemolysis. The colonies often develop a dimpled, then a craterlike appearance (autolysis).
Gram-positive, non-motile, encapsulated, oval diplococci(lancet shape)