Contact us 
My Experiments 
Selective and Differential Medium for the Isolation of Enterobacteriaceae and Other Gram-Negative Bacilli
MacConkey Agar by Liofilchem® is a slightly selective and differential culture medium designed for the isolation, cultivation, and differentiation of Gram-negative enteric bacilli, particularly from clinical samples, pharmaceutical products, food, wastewater, and other materials of sanitary importance. The medium is formulated in accordance with USP/EP/JP harmonized methods for the detection of Escherichia coli in non-sterile pharmaceutical products.
This medium supports clear differentiation between lactose-fermenting organisms, which appear as pink colonies, and non-lactose fermenters, which produce colorless or transparent colonies. It is widely used in clinical and industrial microbiology as a frontline medium for identifying members of the Enterobacteriaceae family.
Intended Use
- Isolation and presumptive identification of Enterobacteriaceae and other Gram-negative organisms.
- Differentiation of lactose fermenters (e.g., E. coli, Klebsiella spp.) from non-fermenters (e.g., Salmonella, Shigella, Proteus spp.).
- Recommended in harmonized pharmacopeial methods (USP/EP/JP) for E. coli detection in non-sterile products.
Typical Composition (per Liter)
| Component | Concentration (g/L) |
|---|---|
| Pancreatic Digest of Gelatin | 17.0 |
| Peptone from Meat | 1.5 |
| Peptone from Casein | 1.5 |
| Lactose | 10.0 |
| Sodium Chloride | 5.0 |
| Bile Salts | 1.5 |
| Agar | 15.0* |
| Neutral Red (pH Indicator) | 0.03 |
| Crystal Violet (Selective Agent) | 0.001 |
| Final pH (at 25°C) | 7.1 ± 0.2 |
*Agar content adjusted based on gel strength to meet performance specifications.
Principle of the Method
- Lactose fermentation lowers pH, causing neutral red to stain colonies pink/red.
- Bile salts and crystal violet inhibit Gram-positive organisms, promoting Gram-negative selectivity.
- Peptones and digests provide essential nutrients for bacterial growth.
-
Differentiation is based on colony color:
- Lactose fermenters: Pink to red colonies, often with bile precipitation.
- Non-lactose fermenters: Colorless or translucent colonies.
Performance Characteristics
| Organism (ATCC®) | Colony Appearance |
|---|---|
| Escherichia coli ATCC® 8739 | Pink colonies with bile precipitate |
| Klebsiella pneumoniae ATCC® 13883 | Pink colonies |
| Salmonella Typhimurium ATCC® 14028 | Colorless colonies |
| Shigella flexneri ATCC® 12022 | Colorless colonies |
| Proteus mirabilis ATCC® 12453 | Colorless colonies |
| Enterococcus faecalis ATCC® 29212 | Small, opaque colonies (inhibited/poor growth) |
| Staphylococcus aureus ATCC® 25923 | Inhibited |
Productivity Ratio (PR) ≥ 0.5 indicates acceptable performance.
Test Procedure
- Inoculate the surface of the agar by streaking or spreading the specimen directly or from enrichment broth.
- Incubate aerobically at 35 ± 2°C for 18–24 hours.
- For E. coli detection in pharmaceuticals, follow USP/EP/JP harmonized methods with pre-enrichment in Tryptic Soy Broth and MacConkey Broth before plating.
Storage & Shelf Life
| Product Type | Storage Conditions | Shelf Life |
|---|---|---|
| Dehydrated Medium | 10–30°C (dry, sealed) | 4 years |
| Ready-to-Use Bottles | 10–25°C, protect from light | 2 years |
| Ready-to-Use Plates | 10–25°C, protect from light | 6 months |
Available Formats
| Format | Packaging | Ref. Code |
|---|---|---|
| 90 mm Ready-to-Use Plates (20) | 2 × 10 plates | 10029 |
| 90 mm Ready-to-Use Plates (100) | 10 × 10 plates | 10029* |
| 100 mL Bottles | 6 × 100 mL | 402240 |
| 200 mL Bottles | 6 × 200 mL | 412240 |
| 500 mL Bottles | 6 × 500 mL | 470090 |
| Dehydrated Medium (100 g) | 1 bottle | 620028 |
| Dehydrated Medium (500 g) | 1 bottle | 610028 |
| Dehydrated Medium (5 kg) | 1 drum | 6100285 |
🚫 Warnings and Precautions
- For in vitro diagnostic use (IVD) only
- For laboratory professional use
- Do not use if packaging is damaged or past expiry
- Always consult the SDS and follow proper biosafety procedures
- Not intended as a standalone diagnostic tool—confirmatory testing required
Liofilchem® MacConkey Agar is a trusted, pharmacopeia-compliant medium for the isolation and differentiation of Gram-negative enteric bacteria. Its reliable performance and compliance with international standards make it ideal for clinical diagnostics, pharmaceutical quality control, and food and environmental microbiology.
IFU
Selective and Differential Medium for the Isolation of Enterobacteriaceae and Other Gram-Negative Bacilli
MacConkey Agar by Liofilchem® is a slightly selective and differential culture medium designed for the isolation, cultivation, and differentiation of Gram-negative enteric bacilli, particularly from clinical samples, pharmaceutical products, food, wastewater, and other materials of sanitary importance. The medium is formulated in accordance with USP/EP/JP harmonized methods for the detection of Escherichia coli in non-sterile pharmaceutical products.
This medium supports clear differentiation between lactose-fermenting organisms, which appear as pink colonies, and non-lactose fermenters, which produce colorless or transparent colonies. It is widely used in clinical and industrial microbiology as a frontline medium for identifying members of the Enterobacteriaceae family.
Intended Use
- Isolation and presumptive identification of Enterobacteriaceae and other Gram-negative organisms.
- Differentiation of lactose fermenters (e.g., E. coli, Klebsiella spp.) from non-fermenters (e.g., Salmonella, Shigella, Proteus spp.).
- Recommended in harmonized pharmacopeial methods (USP/EP/JP) for E. coli detection in non-sterile products.
Typical Composition (per Liter)
| Component | Concentration (g/L) |
|---|---|
| Pancreatic Digest of Gelatin | 17.0 |
| Peptone from Meat | 1.5 |
| Peptone from Casein | 1.5 |
| Lactose | 10.0 |
| Sodium Chloride | 5.0 |
| Bile Salts | 1.5 |
| Agar | 15.0* |
| Neutral Red (pH Indicator) | 0.03 |
| Crystal Violet (Selective Agent) | 0.001 |
| Final pH (at 25°C) | 7.1 ± 0.2 |
*Agar content adjusted based on gel strength to meet performance specifications.
Principle of the Method
- Lactose fermentation lowers pH, causing neutral red to stain colonies pink/red.
- Bile salts and crystal violet inhibit Gram-positive organisms, promoting Gram-negative selectivity.
- Peptones and digests provide essential nutrients for bacterial growth.
-
Differentiation is based on colony color:
- Lactose fermenters: Pink to red colonies, often with bile precipitation.
- Non-lactose fermenters: Colorless or translucent colonies.
Performance Characteristics
| Organism (ATCC®) | Colony Appearance |
|---|---|
| Escherichia coli ATCC® 8739 | Pink colonies with bile precipitate |
| Klebsiella pneumoniae ATCC® 13883 | Pink colonies |
| Salmonella Typhimurium ATCC® 14028 | Colorless colonies |
| Shigella flexneri ATCC® 12022 | Colorless colonies |
| Proteus mirabilis ATCC® 12453 | Colorless colonies |
| Enterococcus faecalis ATCC® 29212 | Small, opaque colonies (inhibited/poor growth) |
| Staphylococcus aureus ATCC® 25923 | Inhibited |
Productivity Ratio (PR) ≥ 0.5 indicates acceptable performance.
Test Procedure
- Inoculate the surface of the agar by streaking or spreading the specimen directly or from enrichment broth.
- Incubate aerobically at 35 ± 2°C for 18–24 hours.
- For E. coli detection in pharmaceuticals, follow USP/EP/JP harmonized methods with pre-enrichment in Tryptic Soy Broth and MacConkey Broth before plating.
Storage & Shelf Life
| Product Type | Storage Conditions | Shelf Life |
|---|---|---|
| Dehydrated Medium | 10–30°C (dry, sealed) | 4 years |
| Ready-to-Use Bottles | 10–25°C, protect from light | 2 years |
| Ready-to-Use Plates | 10–25°C, protect from light | 6 months |
Available Formats
| Format | Packaging | Ref. Code |
|---|---|---|
| 90 mm Ready-to-Use Plates (20) | 2 × 10 plates | 10029 |
| 90 mm Ready-to-Use Plates (100) | 10 × 10 plates | 10029* |
| 100 mL Bottles | 6 × 100 mL | 402240 |
| 200 mL Bottles | 6 × 200 mL | 412240 |
| 500 mL Bottles | 6 × 500 mL | 470090 |
| Dehydrated Medium (100 g) | 1 bottle | 620028 |
| Dehydrated Medium (500 g) | 1 bottle | 610028 |
| Dehydrated Medium (5 kg) | 1 drum | 6100285 |
🚫 Warnings and Precautions
- For in vitro diagnostic use (IVD) only
- For laboratory professional use
- Do not use if packaging is damaged or past expiry
- Always consult the SDS and follow proper biosafety procedures
- Not intended as a standalone diagnostic tool—confirmatory testing required
Liofilchem® MacConkey Agar is a trusted, pharmacopeia-compliant medium for the isolation and differentiation of Gram-negative enteric bacteria. Its reliable performance and compliance with international standards make it ideal for clinical diagnostics, pharmaceutical quality control, and food and environmental microbiology.
IFU
Spécifications
| Pack Size | 6 x 100 mL, 6 x 500 mL, 6 x 200 mL |