CTX-M Rapid Test – EZER™ β-lactamase Detection

What is in the CTX-M Rapid Test?

The EZER™ CTX-M Rapid Test kit contains:

• 20 lateral flow cassettes

• 20 extraction tubes with buffer

• 1 instruction leaflet

The test cassette includes two lines:

• T line (Test) – Indicates CTX-M enzyme presence

• C line (Control) – Confirms test validity

Only 3 drops of prepared extract are needed per test. The result appears within 15 minutes. A red or purple line at the T position (even faint) indicates a CTX-M-positive result.

Role of CTX-M β-lactamases in Resistance

CTX-M enzymes are part of the extended-spectrum β-lactamases (ESBLs), which hydrolyze third-generation cephalosporins such as cefotaxime and ceftriaxone. These enzymes have become globally dominant due to horizontal gene transfer and clonal expansion.

CTX-M enzymes are particularly prevalent in:

• E. coli (especially ST131)

• Klebsiella pneumoniae

• Other Enterobacterales

Among over 170 known CTX-M variants, CTX-M-15 and CTX-M-14 are the most clinically relevant. Rapid detection allows for timely infection control and prevention of nosocomial transmission, while avoiding unnecessary carbapenem use.

About the EZER™ CTX-M Rapid Test

Manufactured by Genesis Biotech, the EZER™ test uses a colloidal gold-based lateral flow system with high-affinity monoclonal antibodies specific to CTX-M β-lactamases.

Performance Summary:

• Sensitivity: 100%

• Specificity: 100%

• Accuracy: 100%

• Detection limit: 250 pg/mL (recombinant enzymes)

Cross-reactivity:

No false positives were observed with over 50 resistance mechanisms, including:

• KPC, NDM, OXA variants

• SHV, TEM, AmpC

• MCR, aac, aad, sul, qnr, tet, van, mecA genes

Validated with 178 bacterial isolates and benchmarked against NG-Test® CTX-M Multi, it demonstrated complete concordance.

Principle and Workflow

The test operates on a simple lateral flow format:

Sample Preparation:

1. Pick 3 bacterial colonies (from blood or MacConkey agar)

2. Suspend in extraction buffer

3. Vortex to homogenize

Test Execution:

1. Add 3 drops (80 μL) of the extract to the cassette

2. Wait exactly 15 minutes

3. Interpret the result:

   • Positive: Red/purple bands at T and C

   • Negative: Band at C only

   • Invalid: No C band – repeat test

The assay is designed for professional in vitro use with Enterobacterales only.

Clinical Application

The EZER™ CTX-M β-lactamases Rapid Test is intended for:

• Clinical microbiology labs performing ESBL screening

• Hospital infection control departments

• Public health surveillance and epidemiology labs

• Outbreak investigations involving multidrug-resistant organisms (MDROs)

Its portability and speed make it especially useful in resource-limited settings where molecular diagnostics may not be available. By identifying CTX-M-positive isolates early, clinicians can avoid broad-spectrum misuse and enforce appropriate isolation measures.

The test supports stewardship by distinguishing CTX-M-targeted resistance from other β-lactam mechanisms, reducing reliance on carbapenems and preserving last-resort therapies.