MacConkey Broth

Selectively and differentially isolate enteric gram-negative bacilli using Thermo Scientific™ Remel™ MacConkey Broth. MacConkey Broth is a modification of the original bile salt broth first described by MacConkey in 1900, which contained litmus as an indicator and sodium taurocholate to inhibit gram-positive organisms¹. In further testing, MacConkey recommended replacing litmus with neutral red². In 1953, Childs and Allen replaced neutral red with bromcresol purple, a less inhibitory indicator³.

Selectively and differentially isolate enteric gram-negative bacilli using MacConkey Broth. This medium is used for presumptive identification of coliforms. Coliforms are organisms that are present in the environment and in the feces of all warm-blooded animals and humans.

Their presence in drinking water indicates that disease-causing organisms (pathogens) could be in the water system.

• Selective: Oxgall is a selective agent which inhibits gram-positive organisms.
• Ease of differentiation: Lactose and bromcresol purple indicator enable the differentiation of lactose fermenting gram-negative bacilli.
• Conforms to USP and EP: It is formulated and tested in conformance with harmonized United States Pharmacopeia (USP)/European Pharmacopeia (EP) guidelines⁴.

This medium contains gelatin peptone that provides amino acids and essential nutrients for bacterial growth. Lactose is a carbon source for energy. Oxgall is a selective agent which inhibits gram-positive organisms. Lactose and bromcresol purple indicator enable the differentiation of lactose fermenting gram-negative bacilli.

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