Commonly Used Selective and Differential Culture Media

• Eosin Methylene Blue Agar (EMBA)

  • Color: Dark Violet
  • Selective for: Gram negative enteric bacilli
  • Inhibitors: Eosin, Methylene blue
  • Differential Indicator: Eosin, MB
  • Product: Acid
  • pH: decrease
• Mc Conkey (MAC agar)

  • Color: Light pink
  • Selective for: Gram negative enteric bacilli
  • Inhibitor: Crystal violet, bile salt, citrate
  • Diff Indicator: neural red
  • Acid: red/dark pink
  • No acid: colorless
  • alkaline: yellow
• Salmonella-Shigella Agar (SSA)

  • Color: Light orange
  • Selective for: Salmonella and Shigella spp.
  • Inhibitor: briliant green, bile salt, citrate
  • Diff Ind: pH: neutral red H2s: ferric ammonium citrate
  • Acid: dark pink
  • No acid: colorless
  • H2s: Salmonella
  • No H2s: Shigella
• Hektoen Enteric Agar (HEA)

  • Color: dark green
  • Selective for: Gram negative enteric bacilli
  • Inhibitor: bile salt, citrate
  • Diff indicator (w/ lactose): bromthymol blue
  • Acid: Orange
  • No acid: Green
  • Alkaline: Blue
  • H2s: Ferric Ammonium Citrate (blackening)
  • Sulfur souce: Sodium thioulfate
• Bismuth Sulfate Agar (BSA)

  • Selective for: Salmonella spp. (Salm. typhi spp)
  • Inhibitor: Bismuth sulfate
  • CHO Indicator: Glucose
  • Product: Black Colonies with silver metallic sheen
• Thiosulfate Citrate Bilesalt Sucrose Agar

  • Color: Light green/ Olive green
  • Selective for: Vibrio spp.
  • Inhibitor: Thiosulfate, Citrate, Bilesalts
  • Differential: Sucrose
  • Indicator: Bromthymol blue
• Mannitol Salt Agar

  • Color: light/salmon pink
  • Selective: staphylococcus spp.
  • Inhibitor: high concentration of salts (7.5%)
  • Acid: Yellow
  • No Acid: Red/ Dark pink
• Lowenstein Jensen (LJ medium)

  • Color: Light green
  • Selective for: Mycobacterim spp.
  • Inhibitor: Malachite green
  • Incubation with light: photochromogen
  • Incubation without light: scotochromogen