Deoxycholate 10% is a diagnostic reagent used primarily for the identification of Streptococcus pneumoniae through the bile solubility test. Each bottle contains 25mL of a sterile aqueous solution of sodium deoxycholate, an anionic bile salt detergent. When added to a suspension of pneumococcal cells, the reagent activates the organism’s autolytic enzymes, resulting in rapid lysis of the bacterial cell wall. This reaction causes the previously turbid suspension to become clear, confirming the presence of S. pneumoniae. Other alpha hemolytic streptococci generally resist bile salt lysis and remain turbid under the same conditions. Because of its reliability and simplicity, the deoxycholate test is widely used in clinical microbiology laboratories for confirmatory identification of pneumococcal isolates.