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Liofilchem® Imipenem+Cloxacillin IMI+CL 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+Cloxacillin IMI+CL Antimicrobial Susceptibility Discs are specialized tools designed for the detection of AmpC β-lactamase overproduction and carbapenem resistance in Gram-negative bacteria. The synergy between Imipenem (IMI) and Cloxacillin (CL) helps differentiate resistance mechanisms, specifically those caused by AmpC enzymes versus other carbapenem resistance mechanisms.
Key Features
- Combination Therapy Detection:
- Detects AmpC-mediated carbapenem resistance using the synergistic activity of Imipenem and Cloxacillin.
- Differentiation of Resistance Mechanisms:
- Helps identify resistance due to porin loss, efflux pumps, or AmpC hyperproduction.
- Global Standards Compliance:
- Designed for use according to CLSI and EUCAST guidelines.
- Ease of Use:
- Compatible with standard disc diffusion methods on Mueller-Hinton Agar.
- Enhanced Sensitivity:
- Provides accurate results for detecting low-level AmpC expression.
Applications
- Target Pathogens:
- Enterobacterales: Escherichia coli, Klebsiella spp., Proteus spp., Serratia spp.
- Non-fermenters: Pseudomonas aeruginosa, Acinetobacter baumannii.
- Resistance Mechanisms:
- AmpC β-lactamase overexpression.
- Porin loss or reduced permeability.
- Efflux pump-mediated resistance.
Technical Specifications
| Feature | Details |
|---|---|
| Active Ingredients | Imipenem 10 µg, Cloxacillin 500 µg |
| Disc Content | Combination of carbapenem and β-lactamase inhibitor |
| Disc Diameter | 6 mm |
| Recommended Media | Mueller-Hinton Agar |
| Incubation Conditions | 35–37°C for 16–20 hours |
| Shelf Life | As indicated on the packaging |
| Storage Conditions | -20°C for long-term; 2–8°C for short-term |
Testing Procedure
- Sample Preparation:
- Prepare a bacterial suspension equivalent to 0.5 McFarland Standard.
- Inoculation:
- Spread the suspension evenly over a Mueller-Hinton Agar plate using a sterile swab.
- Disc Placement:
- Place the IMI+CL disc and a standalone Imipenem disc at least 25 mm apart on the agar surface.
- Incubation:
- Incubate at 35–37°C for 16–20 hours.
- Result Interpretation:
- Measure and compare inhibition zones around the IMI+CL disc and the standalone Imipenem disc.
Interpretation of Results
| Observation | Interpretation |
|---|---|
| Zone diameter for IMI+CL > IMI alone | Synergy observed; AmpC-mediated resistance likely |
| Reduced zones for both discs | Likely porin loss or efflux pump activity |
| Normal susceptibility zones | No AmpC or other carbapenem resistance detected |
Quality Control Data
| Control Strain | Expected Results |
|---|---|
| Escherichia coli ATCC® 25922 | No zone enhancement |
| Pseudomonas aeruginosa ATCC® 27853 | No synergy observed |
| Klebsiella pneumoniae (AmpC-producing clinical isolate) | Zone diameter for IMI+CL > IMI alone |
Advantages
| Feature | Benefit |
|---|---|
| Enhanced Detection of AmpC | Reliable identification of AmpC hyperproducers. |
| Synergy Testing | Differentiates between AmpC and other resistance mechanisms. |
| Ease of Integration | Compatible with standard laboratory workflows. |
| Cost-effective | Simple and efficient method for resistance screening. |
References
- CLSI (Clinical and Laboratory Standards Institute): M100 Performance Standards for Antimicrobial Susceptibility Testing.
- EUCAST (European Committee on Antimicrobial Susceptibility Testing): Breakpoints for Carbapenem Susceptibility.
- Studies on Imipenem+Cloxacillin Synergy for detecting AmpC β-lactamase in Enterobacterales.
Conclusion
The Liofilchem® Imipenem+Cloxacillin IMI+CL Antimicrobial Susceptibility Discs provide a robust method for identifying AmpC-mediated resistance in clinical microbiology. Their high sensitivity, standardized application, and compatibility with established guidelines make them an essential tool in antimicrobial resistance surveillance.