1 / 14

Biochemical Test 2nd part

NEXT UPLODE CONTINUED!

Prabhakar5
Download Presentation

Biochemical Test 2nd part

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biochemical Tests-II Moderator- Dr. Meenakshi Sharma Associate Professor Presented By- Prabhakar Singh Patel M.Sc. Medical Microbiology

  2. Some of the widely used biochemical tests are: • Catalase test • Coagulase test • Oxidase test • Bile esculin hydrolysis • Indole test • MR test • VP test • Urease test • Citrate test • TSI test • Nitrate test • PPA test • OF test • Sugar fermentation test • Decarboxylase test • CAMP • PYR test • DNase test

  3. TSI (Triple Sugar Iron) Test • It is widely used for identification of gram negative bacteria. • It is a composite solid agar medium in a tube having a butt and a slant. • It contains: • Three sugars- glucose, sucrose and lactose in a ratio of 1:10:10. • Phenol red as an indicator of acid production. • Ferric salts as an indicator of H2S production.

  4. Interpretation TSI detects three properties of bacteria Fermentation of sugars (acid production) Non fermenters K/K; red color (alkaline). Glucose fermenter K/A; red/yellow only glucose is fermented. All sugar fermenter A/A; yellow color (acidic). Gas production; bubbles in the butt. H2s production; blackening of the medium.

  5. Nitrate Reduction Test It is used to determine the ability of organism to produce enzyme nitrate reductase, which reduces nitrate into nitrite or free nitrogen gas. All Enterobacteriaceae gives positive result, so with this test one can differentiate Enterobacteriaceae from Gram -ve non- enteric bacteria.

  6. PPA (Phenyl Pyruvic Acid) Test This test is used to determine the ability of an organism to produce an enzyme deaminase This enzyme removes the amine group from the amino acid phenylalanine and produces phenyl pyruvic acid (PPA). PPA reacts with few drops of 10% ferric chloride solution to produce green colour. This is a specific test done for the Proteus, Morganella, and Providencia. PPA gives negative test for all members of Enterobacteriaceae.

  7. OF (Oxidation - Fermentation) Test The Oxidation Fermentation (OF) test was developed by Hugh and Leifson in 1953. They developed OF media to differentiate between oxidative and fermentative bacteria. Oxidative- that produces acid from carbohydrates under aerobic conditions only. Fermentative- that produces acid under both aerobic and anaerobic conditions.

  8. Sugar Fermentation Test It detects an ability of an organism to ferment a specific carbohydrate incorporated in a medium producing acid with or without gas. Basal medium containing single carbohydrate source such as glucose, sucrose, lactose or other carbohydrates is used for this purpose. A pH indicator ( Andrade/phenol red)- will detect the decreased pH due to acid production. Gas production is detected by using an inverted Durham’s tube. Ex:- Neisseria, Corynebacterium, etc.

  9. Decarboxylase Test Neg- Pos- It is used to detect the presence of substrate specific decarboxylase enzyme in the bacteria that breakdown amino acids, such as lysine, arginine, and ornithine to produce alkaline by products which changes the color of the indicator to purple . Cresol red and bromocresol purple are used as an indicators. If positive media changes to purple color.

  10. CAMP (Christie-Atkins-Munch-Peterson) Test CAMP factor is a phospholipase produced by group B Streptococcus that causes synergistic hemolysis with beta hemolysis produced by S. aureus. When GBS is streaked on blood agar plate perpendicular to S.aureus, an enhanced arrowhead – shaped hemolysis is produced at their junction , pointing towards S. aureus streak line.

  11. PYR (Pyrrolidonyl Arylamidase) Test Used for the presumptive identification of group A Streptococci (S. pyogenes). Differentiation of Enterococci from group D beta hemolytic Streptococci. Identification of E.coli from other indole positive, lactose positive, gram negative rods. Broth method – PYR broth inoculation with 5 colonies of pure culture then incubation for 4 hrs. After addition of 2-3 drops of PYR reagent and observe red color within 1-2 min. Disc method – wet PYR test disc in strip with 10 micro lit. D.W. and smear 5-10 colonies of test strain on surface of disc, incubate disc 2 min at RT. Add 1 drop of N,N-dimethylaminocinnamaldehyde and observe for red color within 1-2 min.

  12. DNase Test Its used to determine the ability of an organism to produce DNase enzyme, which hydrolyse DNA and utilize it as a source of carbon and energy for growth. Methyl green form a complex with intact DNA to form the green color of medium. DNase activity depolymerizes the DNA, breakdown the methyl green – DNA complex, which results in the formation of colorless zones around colonies of the test organism.

  13. THANK YOU

More Related