A, Colony lysed (Positive). Negative Result: Suspension remains turbid. Gently wash the solution over the colony with dislodging the colony from the medium. Evaporation may cause the reagent to become more concentrated, therefore affecting the test. When testing using the plate method, care must be taken not to dislodge the colony being tested, thus leading to false-positive results. This test is used to differentiate Streptococcus pneumoniae, which is soluble in bile and bile salts, from alpha- hemolytic Streptococcus which are insoluble.. Catalogue No. 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. 2 Could you please provide me with information of E. faecalis? 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. Bile salts lower the surface tension between the bacterial cell membrane and the medium, thus accelerating the organism’s natural autolytic process. Streptococcus pneumoniae is bile soluble whereas all other alpha-hemolytic streptococci are bile resistant. 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. The working mechanism of the test is not clearly understood; however one theory is that the bile salts facilitate lysis of pneumococcal cells by activating the autolytic enzyme. UK Standards for Microbiology Investigations. 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. Examine for lysis of colony (Disappearance of the colony). Bile salts lower the surface tension of the medium-membrane interface and under these condition, Streptococcus pneumonia is susceptible to disruption by enzyme action thus enhancing the organism’s natural autolysis process. Your email address will not be published. On one-half of the slide, 1 drop of blood was mixed with 1 drop of 2% sodium deoxycholate. Prepare 10% bile salt solution for plate method: Dissolve 10 gram of sodium desoxycholate in 100 ml distilled water. Bile-esculin test is widely used to differentiate Enterococci and Non-enterococcus group D streptococci, which are bile tolerant and can hydrolyze esculin to esculetin, from non-group D viridans group streptococci, which grow poorly on bile. Negative: Intact colony or no change in the integrity of the colony within 30 min. Group A strep b. colonies remain intact. Positive: Colony disintegration or flattening of the colony within 30 minutes, leaving an alpha-hemolytic where colony may be located. It is a low cost, rapid test with good sensitivity and specificity (>90%). Bile Solubility Test is the test which differentiate Streptococcus pneumoniae (positive- soluble) from alpha-hemolytic streptococci (negative- insoluble).Streptococcus pneumoniae is bile soluble whereas all other alpha-hemolytic streptococci are bile resistant.. Bile Solubility Test. Negative: cocci are seen in both test smear and control smear. 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. Pp. Save my name and email in this browser for the next time I comment. Examine each tube by Gram-staining or Methylene blue wet mount for lysis of the cell. Blood (10%, vol/vol) was inoculated into one bottle each of tryptic soy broth and Thiol broth under vacuum with C02 and 0.025% sodium polyanetholsulfonate. Observe again for clearing. teo obispo. 2% sodium deoxycholate (bile salt) solution, 10% sodium deoxycholate (bile salt) solution. When testing using the plate method, care must be taken not to dislodge the colony being tested, therefore leading to false positive results. Bile solubility and latex may not be as reliable when testing alpha-hemolytic colonies without colony morphology typical S. pneumoniae. 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