The Liofilchem® Meropenem+EDTA (MR+ED) Antimicrobial Susceptibility Discs are specifically designed for detecting metallo-beta-lactamase (MBL)-producing bacteria in Gram-negative organisms, including Enterobacterales, Pseudomonas aeruginosa, and Acinetobacter species. These discs utilize the synergistic effect of EDTA, a potent MBL inhibitor, in combination with meropenem, allowing accurate differentiation between carbapenem-resistant bacteria caused by MBL production and other mechanisms.
Key Features
- Dual Detection:
- Combines Meropenem (10 µg) and Meropenem+EDTA on separate discs for comparative analysis.
- Selective Inhibition:
- EDTA binds zinc ions essential for MBL enzyme activity, inhibiting MBL-producing bacteria and restoring susceptibility to meropenem.
- Reliable Differentiation:
- Significant increase in zone diameter with MR+ED indicates MBL production.
- High Sensitivity:
- Detects MBL activity with minimal false positives or negatives.
- Ease of Use:
- Compatible with the standard disc diffusion method on Mueller-Hinton agar.
Applications
| Application | Description |
|---|
| Clinical Diagnostics | Identifies carbapenem resistance due to MBL production in Gram-negative bacteria. |
| Antimicrobial Resistance Studies | Tracks the prevalence of MBL-producing pathogens in healthcare settings. |
| Pharmaceutical Research | Evaluates the efficacy of carbapenem antibiotics in combination therapies. |
Testing Procedure
- Preparation:
- Prepare a bacterial suspension to 0.5 McFarland standard.
- Spread the suspension uniformly on Mueller-Hinton agar plates.
- Application:
- Place the Meropenem (MR) and Meropenem+EDTA (MR+ED) discs on the agar surface using sterile forceps.
- Incubation:
- Incubate plates at 35–37°C for 16–20 hours under aerobic conditions.
- Interpretation:
- Measure and compare the zones of inhibition for both discs:
- A zone diameter increase of ≥7 mm with MR+ED compared to MR alone indicates MBL production.
Storage and Stability
| Condition | Temperature | Duration |
|---|
| Long-Term Storage | -20°C | Until expiration date |
| Short-Term Storage | 2–8°C | Up to 2 weeks |
| During Use | Room Temperature | Immediate use only |
Technical Specifications
| Feature | Details |
|---|
| Active Components | Meropenem (10 µg) and Meropenem+EDTA (10 µg + EDTA) |
| Test Method | Disc diffusion |
| Compatible Media | Mueller-Hinton agar |
| Incubation Conditions | 35–37°C for 16–20 hours |
| Target Pathogens | MBL-producing Gram-negative bacteria |
| Shelf Life | As per expiration date on packaging |
| Pack Sizes | 50 or 100 discs per pack |
Quality Control Data
| Control Organism | Expected Results |
|---|
| Escherichia coli ATCC® 25922 | MR: ≥23 mm; MR+ED: Similar |
| Pseudomonas aeruginosa ATCC® 27853 | MR: ≥18 mm; MR+ED: Similar |
| Klebsiella pneumoniae (MBL-positive strain) | MR: Small zone; MR+ED: Zone diameter increased by ≥7 mm |
| Staphylococcus aureus ATCC® 29213 | Not applicable (Gram-positive control) |
- Positive Controls: Confirm detection of MBL-producing strains.
- Negative Controls: Ensure no false-positive results in non-MBL producers.
Interpretation of Results
| Zone of Inhibition Comparison | Interpretation |
|---|
| MR zone = MR+ED zone | Absence of MBL production. |
| MR zone ≥7 mm smaller than MR+ED zone | Presence of MBL-producing bacteria. |
Comparison with Other Disc-Based Tests
| Test Disc | Recommended Use |
|---|
| Meropenem+EDTA (MR+ED) | Specific detection of MBL beta-lactamase producers. |
| Meropenem+Cloxacillin (MR+CL) | Detection of AmpC beta-lactamase producers. |
| Carbapenemase Combination Discs | General detection of carbapenemase-mediated resistance. |
Advantages
| Feature | Benefit |
|---|
| Dual Testing System | Identifies MBL resistance directly from primary testing. |
| High Sensitivity and Specificity | Reduces false-positive and false-negative results. |
| Ease of Use | Simplified setup minimizes errors and time. |
| Standards Compliance | Adheres to global antimicrobial susceptibility testing guidelines. |
Conclusion
The Liofilchem® Meropenem+EDTA (MR+ED) Antimicrobial Susceptibility Discs provide a reliable and sensitive method for identifying MBL-mediated carbapenem resistance in Gram-negative bacteria. Their precision and adherence to international testing standards make them an essential tool for antimicrobial resistance detection and monitoring programs.
https://www.labmartgh.com/shop/product/9178-liofilchem-r-meropenem-edta-mr-ed-antimicrobial-susceptibility-discs-28424
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