Liofilchem® MacConkey Agar, 90mm Plates

Selective and Differential Medium for Isolation and Identification of Enterobacteriaceae and Other Gram-Negative Bacteria

Liofilchem® MacConkey Agar is a selective and differential culture medium formulated for the isolation and differentiation of Gram-negative enteric bacilli, particularly from clinical specimens, pharmaceuticals, food, water, and materials of sanitary interest. It is especially suited for the identification of lactose-fermenting and non-lactose-fermenting bacteria in compliance with the harmonized methods of the USP, EP, and JP.

Intended Use

• Selectively isolates Gram-negative bacilli from mixed microbial populations.
• Differentiates lactose fermenters (e.g., E. coli, Klebsiella spp.) from non-lactose fermenters (e.g., Salmonella, Shigella, Proteus spp.).
• Widely used in clinical diagnostics, pharmaceutical quality control, and environmental microbiology.

Typical Composition (per Liter)

*Agar concentration adjusted for optimal gel strength.

Method Principle

• Peptones and digests supply nitrogen, amino acids, and vitamins.
• Lactose is the fermentable sugar used for differentiating enteric bacteria.
• Bile salts and crystal violet selectively inhibit Gram-positive organisms.
• Neutral red serves as a pH indicator:
  • Lactose fermenters → pink to red colonies
  • Non-lactose fermenters → colorless colonies

Expected Cultural Characteristics

Applications

• Detection of E. coli in non-sterile pharmaceutical products per USP/EP/JP harmonized methods
• Differentiation of enteric bacilli in clinical stool or urine samples
• Testing of food, wastewater, or environmental swabs
• Used as a subculture medium following enrichment in Tryptic Soy Broth and MacConkey Broth

Test Procedure

1. Inoculate the specimen by streaking directly or from enrichment onto the agar surface.
2. Incubate at 35 ± 2°C for 18–24 hours in aerobic conditions.
3. For harmonized pharmacopeial testing:
   • Pre-enrich sample in TSB, then MacConkey Broth, followed by plating on MacConkey Agar.

Available Product Formats

Storage and Shelf Life

Liofilchem® MacConkey Agar is a reliable and compliant medium for detecting Enterobacteriaceae and other Gram-negative organisms, providing clear colony differentiation based on lactose fermentation. Available in plates, bottles, and dehydrated formats, it is ideal for use in clinical, pharmaceutical, and environmental microbiology laboratories.