Liofilchem® Beta Lactamase Test Kit, 30 Tests

The Beta Lactamase Test is a rapid diagnostic tool designed to detect the presence of beta-lactamase enzymes in Gram-positive and Gram-negative microorganisms. This enzyme plays a critical role in conferring resistance to penicillins and cephalosporins. It is widely used for clinical and research purposes to evaluate antibiotic resistance profiles, aiding in the diagnosis of infections.

Composition:

• Nitrocefin: Chromogenic cephalosporin that reacts with beta-lactamase to change color from yellow to red.
• Phosphate Buffer: Maintains pH stability while preserving enzymatic activity.
• Dimethyl Sulphoxide (DMSO): Enhances solubility of nitrocefin in the strip matrix.

Intended Purpose:

• Detection: Identifies beta-lactamase production in microorganisms, including Staphylococcus aureus, Haemophilus influenzae, Neisseria gonorrhoeae, and Enterobacteriaceae.
• Applications: Useful in clinical microbiology labs to support decisions in antimicrobial therapy.

Kit Content:

• 30 Test Strips: Individually packaged strips containing nitrocefin.
• Instructions for Use (IFU): Detailed guidelines for testing and result interpretation.

Principle of Operation:

• The test utilizes nitrocefin, a chromogenic cephalosporin substrate. Beta-lactamase activity hydrolyzes the beta-lactam ring of nitrocefin, resulting in a distinct color change from yellow to pink/red.

Instructions for Use:

1. Preparation:
   • Retrieve the required number of test strips from the freezer and allow them to reach room temperature.
2. Inoculation:
   • Touch an isolated bacterial colony with a sterile inoculating loop.
   • Streak the colony onto the test area of the strip indicated by the arrows.
3. Placement:
   • Place the inoculated tip of the strip between the lid and base of an inverted Petri dish.
   • Ensure adequate moisture is present for the reaction.
4. Incubation:
   • Incubate at ambient temperature for up to 5 minutes.
   • If negative, extend observation to 15 minutes or up to 1 hour for slow-acting organisms like some staphylococci.

Result Interpretation:

• Positive Reaction: Pink/red color indicates beta-lactamase production.
• Negative Reaction: No color change; the strip remains yellow.

Quality Control:

Storage and Stability:

• Storage Conditions: Store at -20°C in its original packaging.
• Shelf Life: 1 year.

Performance Characteristics:

• High sensitivity and specificity for beta-lactamase activity.
• Detects enzymes from both Gram-positive and Gram-negative organisms.
• Reliable results within minutes to an hour, depending on bacterial strain.

Limitations:

• False Negatives: Some strains, like beta-lactamase-negative, ampicillin-resistant (BLNAR) H. influenzae, may not produce detectable enzymes.
• False Positives: Some organisms may produce insufficient beta-lactamase to induce a reaction unless pre-exposed to antibiotics like methicillin.
• Additional antimicrobial susceptibility testing is recommended for comprehensive analysis.

Warnings and Precautions:

1. For in vitro diagnostic use only.
2. Handle all specimens as potentially infectious.
3. Ensure proper moisture for accurate results.
4. Dispose of used materials according to national and local regulations.

Packaging:

References:

1. O'Callaghan C.H., et al. (1972). Antimicrob. Agents & Chemother. 1:283-288.
2. Shannon K. and Phillips I. (1980). J. Antimicrob. Chemother. 6:617-621.

This test is an essential tool in the identification of beta-lactamase-mediated antibiotic resistance, enabling precise therapeutic interventions.