CTA Sugar

Cystine Tryptic Agar
A media comprised of digested Casein, Sodium Cloride, L-Cystine, Sodium sulfite, Phenol Red, and agar. Also added to the media is a carbohydrate. The media can be produced with a large variety of sugars, or without sugar as a negative control. The media will become semi-solid from the presence of the agarose making it difficult to mix the organism in. Results are read from the area surrounding the stab line. The media is red to start out and will turn yellow as a positive result for fermentation of the specific sugar it's made with.

Source of Information
Data for this test was obtained at this location: https://catalog.hardydiagnostics.com/cp_prod/Content/hugo/CTAMedia.htm