Liofilchem® Cloxacillin CX, Antimicrobial Susceptibility Discs, 5 µg

Liofilchem® Cloxacillin CX Discs (5 µg) are high-quality antimicrobial susceptibility testing (AST) discs designed for use in the Kirby-Bauer disk diffusion method on Mueller-Hinton agar. Each disc contains precisely 5 µg of Cloxacillin, a narrow-spectrum, beta-lactam antibiotic of the penicillinase-resistant penicillin class. Cloxacillin is used primarily to evaluate resistance in Staphylococcus spp., including Staphylococcus aureus and Staphylococcus epidermidis, especially in the detection of methicillin resistance (MRSA). These discs are manufactured under ISO 9001 and ISO 13485 quality systems, ensuring accuracy and consistency in clinical and research microbiology laboratories.

Key Features

• Accurate dosage: Each disc is impregnated with 5 µg of Cloxacillin for standardized AST performance.
• Penicillinase-resistant: Effective against beta-lactamase-producing Staphylococcus strains.
• MRSA screening support: Used as an alternative to oxacillin in methicillin resistance detection protocols.
• Compliant with global standards: Validated against CLSI and EUCAST guidelines.
• Sterile and stable: Supplied in sealed cartridges or canisters with desiccant for extended shelf life.
• Color-coded labeling: For easy identification and efficient workflow integration.

Applications and Use Cases

1. Clinical Microbiology

Used in diagnostic laboratories to:

• Assess susceptibility of:
  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Coagulase-negative staphylococci (CoNS)
• Detect resistance mediated by:
  • Penicillinase (β-lactamase)
  • mecA gene (MRSA)
• Support treatment decisions for:
  • Skin and soft tissue infections
  • Post-operative wound infections
  • Bacteremia and endocarditis

2. MRSA Detection

• Cloxacillin (5 µg) discs may be used as a surrogate for Oxacillin in disk diffusion methods to infer methicillin resistance.
• Helps guide infection control and antibiotic stewardship strategies.

3. Research and Development

• Monitor prevalence and mechanisms of beta-lactam resistance in Staphylococcus spp.
• Study phenotypic correlation with genotypic resistance markers (e.g., mecA/mecC).
• Evaluate performance of beta-lactamase inhibitors in combination with penicillinase-resistant antibiotics.

Use Instructions

1. Prepare Mueller-Hinton agar plates according to standard protocols.
2. Standardize the bacterial inoculum to 0.5 McFarland turbidity.
3. Inoculate the agar surface uniformly using a sterile swab.
4. Apply one Cloxacillin disc (5 µg) using sterile forceps or a disc dispenser.
5. Incubate plates at 35 ± 2 °C for 16–18 hours.
6. Measure the diameter of the inhibition zone in millimeters.
7. Interpret the results using CLSI or EUCAST breakpoints, particularly for Staphylococcus species.

Storage and Shelf Life

• Storage Conditions: 2–8 °C (refrigerated), protected from moisture and light.
• Shelf Life: 2–3 years from the date of manufacture when stored unopened and under recommended conditions.

Liofilchem® Cloxacillin CX Discs (5 µg) are vital diagnostic tools for assessing resistance in Staphylococcus spp., especially for detecting beta-lactamase production and inferring methicillin resistance. They are suitable for routine use in clinical laboratories, research institutes, and antimicrobial resistance surveillance programs. With validated performance, robust manufacturing quality, and international compliance, these discs are a reliable choice for targeted susceptibility testing of Gram-positive cocci.