Liofilchem® KPC + MBL + OXA-48 disc kit (acc. to EUCAST), 50 Tests

The Liofilchem® KPC&MBL&OXA-48 Disc Kit is a phenotypic confirmation test designed to detect carbapenemase-producing Enterobacteriaceae (CPE). Carbapenemase production is a major mechanism of carbapenem resistance, significantly impacting antibiotic treatment choices and infection control measures.

This disc diffusion-based test distinguishes between the three major classes of carbapenemases:

1. Klebsiella pneumoniae carbapenemases (KPC) – Ambler Class A β-lactamases.
2. Metallo-β-lactamases (MBL: VIM, IMP, NDM) – Ambler Class B.
3. OXA-48-like enzymes – Ambler Class D β-lactamases.

The kit uses meropenem (MRP) alone and in combination with inhibitors (EDTA, phenylboronic acid, cloxacillin) to identify the enzyme class responsible for carbapenem resistance. It follows the European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines for antimicrobial resistance surveillance.

Key Features & Benefits

✔ Reliable & Accurate – Differentiates KPC, MBL, and OXA-48-like enzymes in carbapenem-resistant Enterobacteriaceae (CRE).

✔ EUCAST Compliant – Follows international standards for resistance detection.

✔ Supports Infection Control – Aids in early detection of multidrug-resistant bacteria (MDR).

✔ Essential for Clinical Labs – Helps guide effective antibiotic therapy for resistant infections.

✔ Easy-to-Use – Uses disc diffusion method for quick and straightforward interpretation.

Background: Understanding Carbapenemases

1. What are Carbapenemases?

Carbapenemases are β-lactamase enzymes that hydrolyze penicillins, cephalosporins, and carbapenems. These enzymes confer resistance to carbapenems, which are often the last line of defense against multidrug-resistant bacterial infections.

Carbapenem resistance can occur due to:

• Production of carbapenemases (KPC, MBL, OXA-48).
• Overexpression of AmpC β-lactamases combined with porin loss.
• Efflux pump mechanisms reducing antibiotic entry into bacterial cells.

2. Why is Differentiation Important?

• KPC-producing strains can be treated with β-lactamase inhibitors.
• MBL strains require treatment with non-β-lactam antibiotics (e.g., aztreonam + avibactam).
• OXA-48-like enzymes may require temocillin testing for confirmation.

Correct identification of the resistance mechanism is essential for antimicrobial stewardship and infection control programs.

Principle of the KPC&MBL&OXA-48 Disc Test

The Liofilchem® KPC&MBL&OXA-48 Disc Kit detects carbapenemase activity by evaluating the synergy of meropenem (MRP) with specific inhibitors.

Mechanism of Action

1. Phenylboronic acid (BO) inhibits Class A carbapenemases (KPC).
2. EDTA (ED) inhibits Class B metallo-β-lactamases (MBL: VIM, IMP, NDM).
3. Cloxacillin (CL) inhibits AmpC β-lactamases, helping differentiate AmpC overexpression with porin loss from carbapenemase production.
4. Temocillin (TMO) 30 µg is used to confirm OXA-48-like carbapenemases, which do not show synergy with the above inhibitors.

Kit Contents & Specifications

The Liofilchem® KPC&MBL&OXA-48 Disc Kit includes:

✅ 5 x 50 disc cartridges (total 250 discs)

✅ Individually packaged blister packs with a desiccant to maintain stability

✅ Disc types & concentrations:

• Meropenem 10 μg (MRP) – 50 discs
• Meropenem + EDTA (MR+ED) – 50 discs
• Meropenem + Phenylboronic Acid (MR+BO) – 50 discs
• Meropenem + Cloxacillin (MR+CL) – 50 discs
• Temocillin 30 μg (TMO) – 50 discs

Test Procedure: Step-by-Step Guide

1. Sample Preparation

• Use a fresh, pure culture of the test organism.
• Prepare a bacterial suspension equivalent to 0.5 McFarland Standard.
• Use a sterile cotton swab to evenly inoculate a Mueller-Hinton agar plate.

2. Disc Application

• Apply the following discs:
  • MRP (Meropenem 10 µg alone)
  • MR+BO (Meropenem + Phenylboronic Acid)
  • MR+ED (Meropenem + EDTA)
  • MR+CL (Meropenem + Cloxacillin)
  • TMO (Temocillin 30 µg) (only if no synergy is observed).
• Ensure sufficient spacing between discs for accurate zone measurement.

3. Incubation

• Incubate the plate at 36 ± 1°C for 18-24 hours.

4. Interpretation of Results

After incubation, measure the zones of inhibition around each disc:

Quality Control Strains for KPC, MBL, and OXA-48 Testing

• Negative Control: Klebsiella pneumoniae ATCC® 700603
• MBL Positive Control: Klebsiella pneumoniae ATCC® BAA-2146
• KPC Positive Control: Klebsiella pneumoniae ATCC® BAA-1705
• OXA-48 Positive Control: Klebsiella pneumoniae NCTC 13442

Applications & Use Cases

1. Clinical Microbiology Laboratories

• Hospitals & diagnostic labs use the test to confirm carbapenemase production in multidrug-resistant Enterobacteriaceae.
• Helps prevent inappropriate use of β-lactam antibiotics in carbapenem-resistant infections.

2. Infection Control & Epidemiological Surveillance

• Identifies carbapenemase-producing bacteria for hospital infection control programs.
• Supports global antimicrobial resistance (AMR) surveillance programs.

3. Pharmaceutical Research & New Drug Development

• Used in pharmaceutical microbiology to test new antibiotic formulations against resistant bacteria.

Ordering Information

The Liofilchem® KPC&MBL&OXA-48 Disc Kit is a critical diagnostic tool for confirming carbapenemase production, ensuring effective infection control and antibiotic therapy decisions.