Then, add 5 drops of 10% sodium deoxycholate to one of the tubes (labeled ‘test’) and 5 drops of sterile normal saline was added to other tube (labeled’ control’).Prepare a heavy suspension of the organism (equivalent to 1 McFarland standard) from growth on agar media in 0.5 ml of phosphate buffered saline, pH 7.0.mitis strain ATCC 49456 as a negative control Quality control strains for positive control S.1 McFarland standard or McFarland Densitometer.Test organism (α -haemolytic streptococci).The turbidity of a broth suspension visibly clears on addition of bile salts if the organism is soluble. The addition of bile salts activates the autolysins and accelerates the natural lytic reactions observed with cultures of pneumococci. pneumoniae produces autolytic enzymes that account for the central depression or umbilication characteristic of older pneumococcal colonies on agar media. pneumoniae when added to actively growing bacteria in agar or broth media. Principle of Bile Solubility Testīile salts, specifically sodium deoxycholate and sodium taurocholate, have the capacity to selectively lyse S. Bile solubility test uses for identification of Streptococcus pneumoniae.
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