Tryptic Soy Agar with 0.03% Congo Red (TSA w/CR) is a non-selective, differential medium used for the cultivation of a wide variety of non-fastidious microorganisms. Congo red is utilized to stain the cells of fungi and the outer membrane of Gram-negative bacteria. Additionally, studies have indicated virulent Shigella flexneri serotype 2a, grown in the presence of congo red at 37°C, showed increased levels of three proteins with MRS of 43K, 58K, and 63K proteins) in the Sarkosyl-soluble membrane fractions. The observed phenomenon is temperature dependent and is generally correlated with their virulence properties.• Product meets CLSI performance criteria.• TSA w/CR should be used by trained professionals within a laboratory setting. • For in vitro diagnostic (IVD) use.• Product is not intended for use in the diagnosis or treatment of disease or other human conditions.