What media is used in the confirmed test for total coliform bacteria?

• A. BGB
• B. LTB
• C. nutrient agar
• D. none of the above

Answer: (A)

For confirming total coliforms, a selective, differential solid medium is used to verify lactose fermentation by coliforms while inhibiting others. The standard confirmed test employs Brilliant Green Bile (BGB) agar. This medium contains bile salts and a brilliant green dye that suppress many non-coliform bacteria and make lactose-fermenting coliforms stand out. Coliforms that ferment lactose produce visible growth with gas production on this medium, confirming their presence. In contrast, Lauryl Tryptose Broth is used in the presumptive stage to detect gas in liquid medium, nutrient agar is non-selective and doesn’t differentiate coliforms, and “none of the above” isn’t correct since BGB is the medium used.