Bile-Solubility Test- Scope, Principle, Procedure, Results and Interpretation
.bmp)
Scope Bile- soluble test has been used to differentiate the S treptococcus pneumoniae from other alpha-hemolytic streptococci based on ability to lysis in the presence of bile salt. S treptococcus pneumoniae is bile soluble whereas all other alpha-hemolytic streptococci are bile insoluble. Principle Bile salts, specifically sodium deoxycholate and sodium taurocholate, have the capability to lyse Streptococcus pneumoniae selectively when added to actively growing bacteria in agar or broth media. S. pneumoniae produces autolytic enzymes (autolysins) that account for the central depression or umbilication characteristic of older pneumococcal colonies on agar media. The addition of bile salts activates the autolysins and accelerates the natural lytic reaction observed with cultures or pneumococci. The bile-solubility test can be performed either with a broth culture of the organism or with colonies growing on agar media. The turbidity of a broth susp...