Triple Sugar Iron Agar 500g Himedia

HiMedia's Triple Sugar Iron Agar (TSI) is a differential medium for identifying Gram-negative enteric bacteria, containing glucose, lactose, and sucrose, along with a pH indicator (phenol red) and sodium thiosulphate for H2S detection; it differentiates bacteria by observing sugar fermentation (yellow/red slant/butt) and hydrogen sulfide production (blackening). The slant's top is red (alkaline) from peptone use, while the butt turns yellow (acidic) from sugar fermentation (glucose first, then lactose/sucrose), showing different patterns like K/A (alkaline slant/acid butt for glucose fermenters) or A/A (acid/acid for lactose/sucrose fermenters). Key Components & Function

• Sugars: Glucose (low conc.), Lactose, Sucrose (high conc.).
• pH Indicator: Phenol Red (red at alkaline pH, yellow at acidic).
• Sulfur Source: Sodium Thiosulphate (substrate for H2S).
• H2S Indicator: Ferric Salts (react with H2S to form black ferrous sulfide). 

Cultural Characteristics (Appearance)

• Powder: Light yellow to pink, free-flowing.
• Prepared Medium: Pinkish-red, clear to slightly opalescent slant. 

Interpreting Results (Slant/Butt) 

• K/A (Red/Yellow): Glucose fermented, lactose/sucrose not (or minimally).
• A/A (Yellow/Yellow): Glucose, lactose, and/or sucrose fermented.
• K/K (Red/Red): No sugar fermented, only peptones used.
• Gas: Bubbles or cracks in the medium.
• H2S: Black precipitate in the butt. 

Common Uses

• Differentiating Salmonella and Proteus species (often with Urea Agar).
• Biochemical confirmation of enteric pathogens.