2. INTRO
• Phenylethyl Alcohol agar
• Pseudomonas Isolation Agar
• Salmonella – Shigella Agar
• Tellurite Glycine Agar
• TCBS agar
• Xylose Lysine Deoxycholate Agar
15-09-2020Dr.SS - Media and Principle (Part -3)
3. PHENYLETHYL ALCOHOL AGAR
• Used to isolate staphylococci and streptococci from culture
mixtures
• Selective medium – Permits the growth of gram positive
organism
15-09-2020Dr.SS - Media and Principle (Part -3)
4. PHENYL ETHYL ALCOHOL AGAR
• Pancreatic digest of casein - 15g
• Papaic digest of soybean meal - 5g
• Sodium chloride – 5g
• ℬ -phenylethyl alcohol – 2.5g
• Sterile defibrinated sheep blood– 50ml
• Agar – 15g
• pH 7.5 +/- 0.2 at 25ºC
• Nitrogen, carbon, vitamins and minerals
• Interfering with DNA synthesis in gram negative organisms
• Gram positive anaerobes
15-09-2020Dr.SS - Media and Principle (Part -3)
5. PSEUDOMONAS ISOLATION AGAR
• Selective and differential medium
• Isolate nonfermenting gram negative bacteria in clinical
samples, especially Pseudomonas species
15-09-2020Dr.SS - Media and Principle (Part -3)
6. PSEUDOMONAS ISOLATION AGAR
• Peptic digest of gelatin– 20g
• Potassium sulfate -10g
• Magnesium chloride -1.4g
• Iragasan – 25mg
• Glycerol – 20ml
• Agar – 13.6g
• pH -7.2 +/_ 0.3 at 25ºC
• Carbon , nitrogen and essential nutrients
• Pycocyanin production enhancer
• Inhibit the growth of Gram positive and gram negative
bacteria other than Pseudomonas
15-09-2020Dr.SS - Media and Principle (Part -3)
7. SALMONELLA – SHIGELLA AGAR
selective medium to isolate and Salmonella and Shigella
species
Undefined, differential and selective medium
15-09-2020Dr.SS - Media and Principle (Part -3)
9. TELLURITE GLYCINE AGAR
Undefined, selective and differential medium
Isolation of coagulase positive staphylococci
15-09-2020Dr.SS - Media and Principle (Part -3)
10. TELLURITE GLYCINE AGAR
Casein enzyme hydrolysate – 10g
Yeast extract -5g
Mannitol – 5g
Dipotassium phosphate – 5g
Lithium chloride -5g
Glycine – 10g
Agar -16g
pH -7.2 +/_ 0.2 at 25ºC
1%Potassium tellurite – 1ml
• Nitrogen source, vitamin B complex
• Fermentable carbohydrate
• Inhibitors of coagulase negative Staphylococci
• Differential agent
coagulase positive Staphylococci
Reduce tellurite. Black colonies
15-09-2020Dr.SS - Media and Principle (Part -3)
11. THIOSULFATE CITRATE BILE SUCROSE (TCBS) AGAR
Undefined, selective and differential medium
Isolation of Vibrio species
15-09-2020Dr.SS - Media and Principle (Part -3)
12. THIOSULFATE CITRATE BILE SUCROSE (TCBS) AGAR
Sucrose -20g
Dipeptone – 10g
Sodium citrate -10g
Sodium thiosulfate – 10g
Sodium chloride -1og
Yeast extract -5g
Oxbile (oxgall) -5g
Sodium cholate -3g
Ferric citrate -1g
Bromothymolblue – 0.04g
Thymolblue -0.04g
Agar – 15 g
pH 8.6 +/_ 0.2 at 25ºC
• Fermentable carbohydrate
• Electron acceptor for sulfate reducers
• Inhibit the growth of gram positive bacteria
• Sulfur reduction
• Organism. Reduce thiosulfate
H2s + Ferric ions black colonies
15-09-2020Dr.SS - Media and Principle (Part -3)
13. XYLOSE LYSINE DESOXYCHOLATE (XLD) AGAR
Selective and differential medium
Isolation and identification of Shigella and Providencia
15-09-2020Dr.SS - Media and Principle (Part -3)
14. XYLOSE LYSINE DESOXYCHOLATE (XLD) AGAR
lactose -7.5g
sucrose – 7.5g
Sodium thiosulfate -6.8g
L-Lysine – 5g
Sodium chloride -5g
xylose -3.75g
Yeast extract -3g
Sodium desoxycholate -2.5g
Ferric ammonium citrate -0.8g
Phenol red– 0.08g
Agar – 15 g
pH 7.4 +/_ 0.2 at 25ºC
• Decarboxylation
• Fermentable carbohydrate
• Indicate the presence of H2S
• pH indicator
15-09-2020Dr.SS - Media and Principle (Part -3)
15. REFERENCE
• A photography Atlas for the microbiology laboratory, 4th edition – Michael. J. Leboffe, Burton E. Pierce
15-09-2020Dr.SS - Media and Principle (Part -3)
16. QUESTIONS TO THINK
• What is the role of bile salts in the medium
• Find out the role of irgasan in Pseudomonas isolation agar
• How to differentiate lactose fermenting or non fermenting organisms in the
medium
• Which component in the medium is indicate the presence of H2S
• Can you formulate the new medium of your own now?
15-09-2020Dr.SS - Media and Principle (Part -3)
