Lysis depends on the presence of an intracellular autolytic enzyme, an amidase, which is produced by Streptococcus pneumonia and is activated by bile salts. Normal autolysis of S. pneumoniae may be inhibited by a high concentration of bile salts being used. The bile solubility test is based on the observation that Streptococcus pneumoniae visibly lyse when 2% or 10% sodium desoxycholate (bile salts) is applied to the colony under specific condition of time and temperature, but other Streptococci do not lyse. Leave both tubes for 10-15 minutes at 35-37°C. Dissolve 2 gram of sodium deoxycholate into 100 ml sterile distilled water. The slide was air-dried at ambient temperature. On one-half of the slide, 1 drop of blood was mixed with 1 drop of 2% sodium deoxycholate. Prepare a suspension of the organism by adding few colonies from freshly isolated bacterial growth (18-24 hour) in a test tube containing 1-2 ml of sterile saline. Place a drop 10% sodium desoxycholate to the side of a young well-isolated colony (18-24hrs) growing on 5% sheep blood agar. S. pneumoniae has an autolytic enzyme which can be demonstrated by allowing a broth culture to age in the incubator; at 24 hours the broth is turbid; after a few days the medium will become clear. UK Standards for Microbiology Investigations. Could you please provide me with information of E. faecalis? Your email address will not be published. pp. Bile solubility test is a biochemical test used for the differentiation and confirmation of Streptococcus pneumoniae from other alpha-hemolytic Streptococci.. Reply. Shake or vortex to form a uniform suspension. Positive: Streptococcus pneumoniae ATCC 49619, Negative: Enterococcus faecalis ATCC 29212, Tags: Bile Solubility, Bile Solubility Test, Bile Solubility Test Limitation, Direct plate method of Bile Solubility Test, Direct slide blood culture method of Bile Solubility Test, Principle of Bile Solubility Test, Procedure of Bile Solubility Test, Quality Control of Bile Solubility Test, Result Interpretation of Bile Solubility Test, Test tube method of Bile Solubility Test, Your email address will not be published. The rapid identification of microorganisms recovered in blood can provide information about the source of the infectious process and guide the specific therapeutic management of the septic patient. If negative, continue to incubate up to 3 hours. Do not use if bile reagent is not clear and very light amber. Bile Solubility Test is the test which differentiate Streptococcus pneumoniae (positive- soluble) from alpha-hemolytic streptococci (negative- insoluble). Autolysin of S. pneumoniae is responsible for central depression or … 5. 199. The bile (sodium deoxycholate) solubility test distinguishes Streptococcus pneumoniae from all other alpha-hemolytic streptococci. Positive Result: No cocci are seen in the test smear and control smear shows intact bacteria. Incubate the plate at 35-37°C for 15-30 minutes or until the drop has evaporated. The test should not be performed on old cultures, as the active enzyme may be lost. Dalynn Biologicals. Principle of Bile Solubility Test. RB60. Observe the tubes for clearing of turbidity after 10-15 minutes. (bile insoluble) from S. pneumoniae (bile soluble) Latex agglutination card test for Lancefield serotyping of beta hemolytic strains 63-64. Gently wash the solution over the colony with dislodging the colony from the medium. When testing using the plate method, care must be taken not to dislodge the colony being tested, therefore leading to false positive results. Bile salts lower the surface tension between the bacterial cell membrane and the medium, thus accelerating the organism’s natural autolytic process. NOTE: Store at 15-30°C. The numbers of organisms present in the blood treated with sodium deoxycholate and in the untreated blood were compared. Bile salts will not induce clearing of a killed culture or one that is too acid. bile solubility = neg PYR = + SXT = R optochin = R hippurate = +/-6.5% salt = + bile esculin = + bacitracin = R a. Direct plate method of Bile Solubility Test, Direct slide blood culture method of Bile Solubility Test, Result Interpretation of Bile Solubility Test, PYR ( L-Pyrrolidonyl-β-Naphthylamide) Test- Principle, Uses, Procedure, Result Interpretaion, Examples and Limitation, HAEMAGGLUTINATION ASSAY – VIRAL QUANTITATION. Bile Solubility Test. District Laboratory Practice in Tropical Countries, Part 2, 2nd Edition. Bile solubility test is not reliable with old cultures since they have lost their active enzyme, resulting in a false-negative test. 2 Negative: Intact colony or no change in the integrity of the colony within 30 min. Modification of the Bile Solubility Test for Rapid Identification of. Bile solubility is used only to differentiate. Positive: Colony disintegration or flattening of the colony within 30 minutes, leaving an alpha-hemolytic where colony may be located. 3 Adjust the suspension to that of 0.5-1 McFarland standard. If the direct plate is difficult to interpret, the test should be repeated using the tube or slide method. Patrick R. Murray. The bile solubility test has been used as an essential test for the differentiation of S. pneumoniae as it allows the distinction between the two species S. pneumoniae and Streptococcus pseudopneumoniae, which is a challenging task. 0 Examine for lysis of colony (Disappearance of the colony). Evaporation may cause the reagent to become more concentrated, therefore affecting the test. Group A strep b. Storage of the reagent at cool temperature can cause it to thicken. 1 Dispense 2 drops of 2% sodium desoxycholate into the tube labelled TEST. Alpha or beta hemolytic on blood agar, depending on species (gamma reclassified as Enterococcus) Bile solubility test (sodium deoxycholate) to distinguish alpha hemolytic species: Viridans group Strep. When testing using the plate method, care must be taken not to dislodge the colony being tested, thus leading to false-positive results. Partially soluble strains that have optochin zones of inhibition of less than 14mm are not considered pneumococci. Incubate the culture plate at 35-37°C for 30 minutes. Prepare 10% bile salt solution for plate method: Dissolve 10 gram of sodium desoxycholate in 100 ml distilled water. Examine for lysis of colony ( Disappearance of the colony with dislodging colony... 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