INDOLE TEST for identification of bacteria.pptx

INDOLE TEST for identification of bacteria.pptx

• 1.
  INDOLE TEST Presented by- Dr.Ananya Verma PG Resident Microbiology Department MGMMC, Indore
• 2.
  INDEX • Purpose • Principle •Media and reagents • Procedure • Result • Interpretation • Precautions
• 3.
  Purpose • To aidin differentiation between genera: E.coli from Klebsiella, enterobacter species. Cardiobacterium hominis from Eikenella, Kingella species. • To aid in differentiation between species:  Proteus mirabilis (indole negative) from Proteus vulgaris (indole positive).  Klebsiella pneumoniae (indole negative) from Klebsiella oxytoca (indole positive).  Citrobacter freundii (indole negative) from Citrobacter koseri (indole positive).
• 4.
  Principle • This testdemonstrate the ability of certain bacteria to decompose the amino acid tryptophane to indole, which accumulates in the medium.
• 5.
  Kovacs’Indole Reagent • p-Dimethylaminobenzaldehyde10 g • Con. Hydrochloric Acid 20 ml • Pure amyl/ isoamyl Alcohol 150 ml Ehrlich’s Indole Reagent • p-Dimethylaminobenzaldehyde 1 g • Con. Hydrochloric Acid 20 ml • Ethyl Alcohol 95 ml Add 1ml xylene to 24 h incubated broth tube before adding Ehrlich’s reagent.
• 6.
  Procedure • Take asterilized test tubes containing 4 ml of peptone broth. • Inoculate the tube aseptically by taking the growth from 18 to 24 hrs culture. • Incubate the tube at 37°C for 24-28 hours. • Add 0.5 ml of Kovac’s reagent to the broth culture. • Observe for the presence or absence of ring.
• 7.
  Quality Control • PositiveControl: Escherichia coli ATCC 25922 • Negative Control: Psuedomonas aeruginosa ATCC 27853
• 8.
  Result
• 9.
  Interpretation • Positive: Formationof a pink to red color (“cherry-red ring”) at the interface of the medium within seconds. • Examples: Escherichia coli, Klebsiella oxytoca, Proteus vulgaris, Plesiomonas shigelloides,Pasteurella multocida, Enterococcus faecalis, and Vibrio sp. • Negative: No color change even after the addition of appropriate reagent. • Examples: Enterobacter aerogeness, Klebsiella pneumoniae., Neisseria sp., Proteus mirabilis, Pseudomonas sp.,Salmonella sp., Serratia sp., Yersinia sp.
• 10.
  Precautions • Some organismsforms indole but break it down rapidly False negative (Clostridium sp.) • Peptone medium must be free from glucose (glucose fermenting bacteria) Increase acidity Decrease tryptophnase activity
• 11.
  • Cultures testedfor indole production must be incubated aerobically Decrease oxygen tension Decrease indole production • Xylene should be added to test medium before Ehrlich’s reagent. (Indole is soluble in organic compound, xylene helps to extract indole) • Store both reagents in refrigerator.
• 12.
  THANK YOU...