Ans- A Ref- SELECTIVE MEDIA Those culture media that permits the required bacterium to grow and selectively inhibit unwanted commensals and contaminants are termed selective media. When the same approach is employed for liquid culture medium, it is called enrichment broth. Any medium can be made selective by addition of some inhibitory substances or altering its property. Some selective media also behave as indicator media. Various techniques are employed to make a medium selective. These are: Addition of antibiotics Addition of chemicals Addition of dyes Altering the pH Combination of any of the above Selective media containing antibiotics: Name of the medium Selective for Antibiotics Thayer Martin Agar N.gonorrhoeae Vancomycin, Colistin, Nystatin PNF Medium b-hemolytic Streptococci Polymyxin B, Neomycin, Fusidic Acid Charcoal Blood Agar B.pertussis Cephalexin Modified New York City Medium N.gonorrhoeae Colistin, Lincomycin, Trimethoprim and Amphotericin B Knisely's Medium (PLET) B.anthracis Polymyxin B Kirchner Medium M.tuberculosis Polymyxin B, Carbenicillin, Trimethoprim and Amphotericin B Skirrow's Medium C.jejuni Vancomycin, Polymyxin B, Trimethoprim Selective Buffered Charcoal Yeast Extract Agar Legionella pneumophila Vancomycin, Polymyxin B Selective media containing chemicals Name of the medium Selective for Chemical Mannitol Salt Agar, Salt Milk Agar S.aureus 10% NaCl Potassium tellurite medium (Hoyle's, Tinsdale) C.diphtheriae 0.04% Potassium tellurite McConkey's Agar (low selective) Enterobacteriaceae Bile salt XLD Agar, DCA Salmonella, Shigella Bile salt Pseudosel Agar (Cetrimide Agar) P.aeruginosa Cetrimide Pseudomonas Isolation Agar P.aeruginosa Irgasan Monsur's Tellurite Taurocholate Gelatin Agar V.cholerae Potassium tellurite Bile Esculin Agar Enterococci Bile salt Selective media containing dyes Name of the medium Selective for Dye Crystal Violet Blood Agar S.pyogenes 0.0002% crystal violet Lowenstein Jensen Medium M.tuberculosis Malachite green Wilson & Blair's Brilliant Green Bismuth Suphite Agar S.typhi Brilliant green Selective media with altered pH Name of the medium Selective for pH TCBS Agar V.cholerae 8.6 Monsur's Tellurite Taurocholate Gelatin Agar V.cholerae 8.5