Liofilchem™ MTS™ Ertapenem/Ertapenem+Cloxacillin ETP/ECX 0.125-8/0.032-2, MIC Test strips

Liofilchem™ MTS™ Ertapenem/Ertapenem+Cloxacillin (ETP/ECX) MIC Test Strips are antimicrobial susceptibility test strips designed to detect and differentiate carbapenem resistance in Enterobacteriaceae and other Gram-negative pathogens. These test strips combine Ertapenem, a carbapenem antibiotic, and Cloxacillin, an agent that targets beta-lactamase enzymes, to provide an efficient method for identifying resistance mechanisms, particularly AmpC beta-lactamases and carbapenemases.

The test strips provide MIC values (minimum inhibitory concentration) that help clinicians and microbiologists assess the effectiveness of Ertapenem against Gram-negative pathogens and determine the presence of beta-lactamase-mediated resistance.

Product Features

• Combination Testing: The strip combines two agents:
  • Ertapenem (carbapenem) to test the general resistance to beta-lactam antibiotics.
  • Cloxacillin to inhibit the activity of beta-lactamases, especially AmpC and carbapenemases.
• Wide MIC Range: The strips are designed to test against a range of concentrations:
  • Ertapenem (0.125-8 µg/mL)
  • Cloxacillin (0.032-2 µg/mL)
• Accurate Resistance Profiling: The MIC values allow for precise identification of resistant strains, helping to determine if carbapenem resistance is due to AmpC or carbapenemase production.
• Sensitivity and Selectivity: These strips have high sensitivity for detecting carbapenem-resistant strains and provide specific information about beta-lactamase activity.

Test Procedure

1. Preparation:
   • Prepare an inoculum from a freshly cultured bacterial isolate. The inoculum should be equivalent to a 0.5 McFarland standard.
   • Swab the inoculum evenly over an agar plate (e.g., Mueller-Hinton Agar) using a sterile swab. Ensure uniform distribution for accurate results.
2. Application of the Strips:
   • Place the ETP/ECX MIC test strips on the inoculated agar plate.
   • The strips should be placed approximately 10-15 mm apart to avoid interference.
   • Ensure the strips are placed with their flat side down on the plate to avoid contamination.
3. Incubation:
   • Incubate the plate aerobically at 35–37°C for 16-20 hours.
   • It is recommended to incubate for 18 hours for optimal results, though it may vary depending on the pathogen.
4. Reading the Results:
   • After incubation, measure the diameter of the inhibition zone around the MIC test strip.
   • The zone of inhibition indicates bacterial susceptibility, while the MIC is determined based on the concentration of the antibiotic where bacterial growth is inhibited.
   • Compare the zone size to the standard CLSI or EUCAST guidelines to determine resistance or susceptibility.
   The breakpoint interpretation will differ depending on the species and the antimicrobial susceptibility testing standards (e.g., CLSI, EUCAST).
5. Resistance Detection:
   • An increase in the zone of inhibition when Cloxacillin is used indicates the presence of beta-lactamase activity, which could be due to AmpC beta-lactamases or carbapenemases.
   • If no zone enlargement occurs with the combination of Ertapenem and Cloxacillin, this suggests that carbapenem resistance is not due to beta-lactamase inhibition but might be due to other mechanisms like efflux pumps or porin channel mutations.

Reference Data

These reference breakpoints are based on EUCAST or CLSI guidelines and are provided as general guidelines. Please refer to local guidelines for region-specific interpretation.

Control Strains:

Storage Conditions

• Long-term Storage: Store the MIC strips at -20°C to maintain the stability and efficacy of the test.
• Short-term Storage: Store the strips at 2-8°C for short-term use.
• Expiry: The strips should be used before the expiry date printed on the label.
• Keep the strips in their original packaging to prevent exposure to moisture, heat, and light.

Shelf Life:

• Shelf life is typically 24 months when stored correctly in the original packaging at recommended temperatures.

Key Advantages

• Rapid and Efficient: Provides results within 18-20 hours, allowing quick decisions regarding treatment options.
• Dual-Agent Testing: The combination of Ertapenem and Cloxacillin makes this method particularly useful for detecting carbapenem-resistant strains, including those resistant due to AmpC beta-lactamases and carbapenemases.
• Cost-Effective: More affordable and simpler than molecular testing, making it ideal for routine testing in clinical microbiology laboratories.
• Versatile: Can be used with a variety of Gram-negative bacterial pathogens, including common nosocomial pathogens like Escherichia coli, Klebsiella pneumoniae, and Enterobacter spp..

Conclusion

Liofilchem™ MTS™ Ertapenem/Ertapenem+Cloxacillin (ETP/ECX) 0.125-8/0.032-2, MIC Test Strips offer a reliable and cost-effective solution for detecting carbapenem resistance in clinical isolates. These test strips combine Ertapenem and Cloxacillin to evaluate resistance mechanisms, particularly beta-lactamase activity. By using these test strips, microbiology labs can quickly identify AmpC-producing and carbapenem-resistant organisms, enabling better antimicrobial stewardship and more informed treatment choices.

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