Assuming an alpha hemolytic reaction (not well seen in the image), viridans streptococcus and S.

Assuming an alpha hemolytic reaction (not well seen in the image), viridans streptococcus and S. pneumoniae are the two possible responses. However, these colonies are far too mucoid for viridans streptococci; therefore, S. pneumoniae is the most likely choice. Also, the colonies are much too large and the hemolytic reaction is wrong for S. pyogenes or S. agalactiae.

A patient was admitted to the hospital recently with an obvious infection. A sputum specimen was submitted and the microbiologist inoculated it to sheep blood agar. Based on the colony morphology and the alpha hemolysis seen in the image to the right, the most likely identification is: