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Liofilchem® Imipenem+EDTA IMI+ED Antimicrobial Susceptibility Discs
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Specifications:
| Application | Clinical microbiology |
| Storage Temperature | -20°C |
| Product Type | Antibiotic Disc |
| Product Brand | Liofilchem |
| Product Grade | Microbiology grade |
The Liofilchem® Imipenem+EDTA IMI+ED Antimicrobial Susceptibility Discs are diagnostic tools designed for the phenotypic detection of metallo-β-lactamase (MBL) production in Gram-negative bacteria. These discs combine imipenem (a carbapenem antibiotic) and EDTA (a chelating agent), allowing the differentiation of MBL-mediated resistance from other carbapenem resistance mechanisms.
Key Features
- Selective Detection of MBL Activity:
- Effective in identifying resistance due to MBL production by chelating divalent cations required for MBL enzymatic activity.
- Dual-Action Testing:
- Synergistic action of imipenem and EDTA distinguishes MBL-producing strains from other carbapenem-resistant organisms.
- Global Compliance:
- Conforms to international standards, including CLSI and EUCAST guidelines for antimicrobial susceptibility testing.
- Versatile Application:
- Applicable to a wide range of Gram-negative pathogens, including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter spp..
- Simple Laboratory Workflow:
- Compatible with disc diffusion methods on Mueller-Hinton Agar for routine diagnostic use.
Applications
| Pathogen Group | Target Species | Mechanism Detected |
|---|---|---|
| Enterobacterales | Escherichia coli, Klebsiella spp. | Metallo-β-lactamase (MBL) production |
| Non-Fermenters | Pseudomonas aeruginosa, Acinetobacter spp. | MBL-mediated carbapenem resistance |
| Others | Proteus mirabilis, Serratia spp. | Differentiation from efflux or porin loss |
Technical Specifications
| Feature | Details |
|---|---|
| Active Ingredients | Imipenem (10 µg), EDTA (500 µg) |
| Disc Diameter | 6 mm |
| Recommended Media | Mueller-Hinton Agar |
| Incubation Conditions | 35–37°C for 16–20 hours |
| Shelf Life | Refer to package labeling |
| Storage Conditions | -20°C for long-term; 2–8°C for short-term |
| Zone Interpretation | Measured in mm, compared with CLSI/EUCAST standards |
Testing Procedure
- Preparation:
- Prepare a bacterial suspension equivalent to 0.5 McFarland Standard.
- Inoculate the suspension evenly on Mueller-Hinton Agar plates.
- Disc Placement:
- Place an IMI+ED disc alongside a standalone imipenem disc (control) at least 25 mm apart.
- Incubation:
- Incubate plates at 35–37°C for 16–20 hours.
- Interpretation:
- Measure inhibition zones around the discs.
- Compare the zone diameters of IMI+ED and imipenem-only discs.
Result Interpretation
| Observation | Interpretation |
|---|---|
| Zone diameter for IMI+ED > IMI alone | Positive for MBL production |
| Reduced zone sizes for both discs | Non-MBL carbapenem resistance (e.g., efflux pump) |
| Normal susceptibility zones | No carbapenem resistance detected |
Quality Control Data
| Control Strain | Expected Zone Diameter |
|---|---|
| Escherichia coli ATCC® 25922 | ≥23 mm (No synergy observed) |
| Pseudomonas aeruginosa ATCC® 27853 | No zone enhancement |
| Klebsiella pneumoniae (MBL positive) | Zone diameter for IMI+ED > IMI alone |
| Proteus mirabilis | Resistant, no synergy |
Advantages
| Feature | Benefit |
|---|---|
| High Specificity | Reliable identification of MBL-producing strains. |
| Cost-effective Detection | Simple and economical phenotypic testing method. |
| Ease of Use | Compatible with routine laboratory workflows. |
| Broad Applicability | Covers both Enterobacterales and non-fermenters. |
Comparison with Other Methods
| Parameter | IMI+ED Discs | Molecular Methods |
|---|---|---|
| Cost | Affordable | Expensive |
| Time to Results | 16–20 hours | Varies (24–48 hours typical) |
| Ease of Use | Simple disc diffusion method | Requires specialized equipment |
| Scope | MBL detection only | Detects multiple resistance genes |
References
- CLSI (Clinical and Laboratory Standards Institute): M100 Performance Standards for Antimicrobial Susceptibility Testing.
- EUCAST (European Committee on Antimicrobial Susceptibility Testing): Guidelines for phenotypic detection of MBL.
- Scientific Literature:
- "Detection of Carbapenem Resistance in Enterobacteriaceae," Journal of Clinical Microbiology.
- "Phenotypic Methods for Identifying MBL Production in Pseudomonas aeruginosa," International Journal of Infectious Diseases.
Conclusion
The Liofilchem® Imipenem+EDTA IMI+ED Antimicrobial Susceptibility Discs are reliable and cost-effective tools for identifying metallo-β-lactamase-producing organisms. With their high specificity, compatibility with standard laboratory workflows, and adherence to global testing guidelines, they are indispensable for antimicrobial resistance surveillance and clinical diagnostics.