Solubility in the presence of sodium deoxycholate is characteristic of which organism?

Solubility in the presence of sodium deoxycholate is characteristic of which organism?

• A. Enterococcus faecalis
• B. Streptococcus agalactiae
• C. Streptococcus mutans
• D. Streptococcus pneumoniae

Answer: (D)

Bile solubility distinguishes Streptococcus pneumoniae from other alpha-hemolytic streptococci. S. pneumoniae dissolves in the presence of sodium deoxycholate because bile salts activate autolysins in its cell wall, causing rapid lysis and clearing of the colonies. This property is why the organism is described as bile soluble. Other streptococci, such as the viridans group, do not lyse in bile salts and remain visible. Among the listed organisms, Enterococcus faecalis, Streptococcus agalactiae, and Streptococcus mutans are not bile soluble, so they do not show this dissolution effect.

Bile solubility distinguishes Streptococcus pneumoniae from other alpha-hemolytic streptococci. S. pneumoniae dissolves in the presence of sodium deoxycholate because bile salts activate autolysins in its cell wall, causing rapid lysis and clearing of the colonies. This property is why the organism is described as bile soluble. Other streptococci, such as the viridans group, do not lyse in bile salts and remain visible. Among the listed organisms, Enterococcus faecalis, Streptococcus agalactiae, and Streptococcus mutans are not bile soluble, so they do not show this dissolution effect.