Mucoid: Bacterial colonies that appear moist and sticky (resembling mucus).
Bile Solubility: The bile solubility test is a qualitative procedure for determining the ability of bacterial cells to lyse in the presence of bile salts (sodium desoxycholate) under specific conditions of time and temperature. The test is primarily used to differentiate bile soluble Streptococcus pneumoniae from bile insoluble alpha-hemolytic streptococci.
Optochin: Sensitivity to optochin (ethylhydrocupreine hydrochloride) is a well established phenomenon for Streptococcus pneumoniae. A positive presumptive identification of S. pneumoniae is made when a well defined zone of inhibition results around a disk impregnated with optochin. Other alpha-hemolytic streptococci do not display this zone of inhibition when in the presence of optochin.
 Streptococcus pneumoniae:

  ▪ Colonies more mucoid, may have concave centers.

  ▪ Dissolve in 10 min with bile (sodium desoxycholate)

  ▪ Zone of inhibition around optochin (P) disk

BAP or SBA: An abbreviation for blood agar plate or sheep bloog agar. Blood agar contains mammalian blood (usually sheep, rabbit or hrose), typically at a concentration of 5-10%. Blood agar is an enriched media used to isolate bacteria and to detect hemolytic activity.

Alpha streptococci vs Streptococcus pneumoniae

on BAP

@ Ellen Jo Baron 2007
Viridans streptococci: 

  ▪ Pathogens only in blood cultures. 

  ▪ Colonies smaller & more dry.

  ▪ Will not dissolve with bile.  

  ▪ No zone around P disk.

 No zone around P disk
Optochin: Sensitivity to optochin (ethylhydrocupreine hydrochloride) is a well established phenomenon for Streptococcus pneumoniae. A positive presumptive identification of S. pneumoniae is made when a well defined zone of inhibition results around a disk impregnated with optochin. Other alpha-hemolytic streptococci do not display this zone of inhibition when in the presence of optochin.
 Optochin Sensitive
  After bile added