The Liofilchem™ EMB Agar, Levine is a selective and differential medium designed for the isolation of gram-negative enteric bacteria, particularly coliforms, as per the United States Pharmacopeia (USP). It is commonly used for analyzing clinical specimens, food, and dairy products to detect and confirm the presence of coliforms.
Key Features
- Selective and Differential:
- Differentiates between lactose fermenters (e.g., coliforms) and non-fermenters (e.g., Salmonella spp. and Shigella spp.) based on colony color.
- Conforms to USP Standards:
- Ensures accuracy and reliability for pharmaceutical, food, and clinical applications.
- Inhibits Gram-Positive Growth:
- Methylene blue acts as a selective agent, partially inhibiting Gram-positive organisms.
- Convenient and Versatile:
- Suitable for use in microbiological analysis of food, dairy products, and clinical samples.
Typical Formula (g/L)
Component | Amount |
---|
Peptone | 10.0 |
Lactose | 10.0 |
Dipotassium Phosphate | 2.0 |
Eosin Y | 0.4 |
Methylene Blue | 0.065 |
Agar | 15.0 |
Final pH (at 25°C) | 7.2 ± 0.2 |
Applications
- Food Microbiology:
- Detection and confirmation of coliforms in dairy and processed food products.
- Clinical Microbiology:
- Isolation of gram-negative enteric bacteria from clinical specimens.
- Environmental Monitoring:
- Assessment of water and environmental samples for coliform contamination.
Preparation Instructions
- Suspend 37.5 g of EMB Agar powder in 1 liter of distilled water.
- Heat gently to dissolve completely.
- Autoclave at 121°C for 15 minutes.
- Cool to 45-50°C, mix thoroughly, and pour into sterile Petri dishes.
Technique
- Specimen Inoculation:
- Streak the medium with the specimen using standard microbiological procedures.
- Incubation:
- Incubate plates at 35 ± 2°C for 18–24 hours, protected from light.
- If no growth is observed after 24 hours, reincubate for another 24 hours.
Interpretation of Results
Colony Type | Interpretation |
---|
Blue-black colonies (with metallic sheen) | Lactose fermenters (e.g., Escherichia coli). |
Pink colonies | Slow lactose fermenters (e.g., Klebsiella pneumoniae). |
Colorless, transparent, or amber colonies | Non-fermenters (e.g., Salmonella spp., Shigella spp.). |
Pinpoint colonies | Gram-positive organisms (e.g., Streptococcus faecalis). |
Storage and Shelf Life
- Storage:
- Dehydrated powder: 10–30°C in original container.
- Prepared plates: 2–8°C, protected from light.
- Shelf Life:
- Dehydrated medium: 4 years from the date of manufacture.
Quality Control
Microorganism | ATCC | Growth | Colony Appearance |
---|
Escherichia coli | ATCC 25922 | Good | Green metallic sheen |
Klebsiella pneumoniae | ATCC 13883 | Good | Pink colonies |
Proteus mirabilis | ATCC 25933 | Good | Colorless colonies |
Pseudomonas aeruginosa | ATCC 27853 | Good | Colorless colonies |
Salmonella typhimurium | ATCC 14028 | Good | Colorless colonies |
Streptococcus faecalis | ATCC 19433 | Inhibited | --- |
Warnings and Precautions
- For in vitro diagnostic use only.
- Handle all specimens and media as potentially infectious.
- Follow standard aseptic techniques during handling.
- Dispose of waste according to local and national regulations.
Advantages
- Highly Selective: Inhibits Gram-positive bacteria, enhancing the isolation of gram-negative enteric organisms.
- Clear Differentiation: Visual differentiation of lactose fermenters and non-fermenters through colony color.
- Standards Compliant: Meets USP requirements, ensuring reliable results in clinical and food microbiology.
Packaging
Product | Quantity | Catalog Number |
---|
EMB Agar (Dehydrated) | 500g | 610019 |
EMB Agar (Dehydrated) | 100g | 620019 |
References
- Holf-Harris and Tongue (1916). J. Infect. Dis. 18:596.
- Levine (1918). J. Infect. Dis. 23:43.
- Marshall ed. (1993). Standard Methods for the Examination of Dairy Products, 16th ed.
- Downes and Ito ed. (2001). Compendium of Methods for the Microbiological Examination of Foods, 4th ed.
- USP 25/NF 20 (2002). United States Pharmacopeial Convention.
Why Choose Liofilchem EMB Agar?
- Proven Accuracy: Trusted for reliable isolation and differentiation of enteric bacteria.
- Broad Application: Suitable for food, clinical, and environmental microbiology.
- Ease of Use: Pre-measured powder simplifies preparation and ensures consistency.
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