Liofilchem® Oxacillin OX, Antimicrobial Susceptibility Discs

Liofilchem® Oxacillin (OX) Antimicrobial Susceptibility Discs, available in 1 µg and 5 µg strengths, are premium, ready-to-use filter paper discs impregnated with oxacillin, a narrow-spectrum beta-lactam antibiotic in the penicillinase-resistant penicillin class. These discs are used for in vitro susceptibility testing of Staphylococcus spp., particularly for detecting methicillin resistance (MRSA) in Staphylococcus aureus and Staphylococcus epidermidis using the Kirby-Bauer disk diffusion method.

Produced under strict ISO 9001 and ISO 13485 standards, Liofilchem® oxacillin discs ensure consistent potency, accurate zone measurement, and compliance with international AST standards (CLSI/EUCAST).

Key Features

• Two dosage formats:
  • 1 µg disc: Optimized for high-sensitivity detection of methicillin-resistant Staphylococcus aureus (MRSA) using Mueller-Hinton agar with 2% NaCl.
  • 5 µg disc: Applied in broader screening of Staphylococcus spp., particularly in veterinary and surveillance labs.
• Standardized for MRSA detection:
  Essential in clinical diagnostics for confirming resistance to penicillinase-resistant β-lactams.
• CLSI/EUCAST validated:
  Compatible with international zone size interpretation criteria.
• Stable & sterile:
  Sealed packaging with desiccant ensures long-term stability and sterility of each disc.
• Color-coded & labeled:
  For efficient identification during susceptibility workflows.

Applications and Use Cases

1. Clinical Microbiology

• Detection of methicillin resistance in Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS).
• Distinguish between beta-lactam susceptible and resistant Staphylococcus spp. in bloodstream, wound, and respiratory samples.

2. Infection Control and Epidemiology

• Routine MRSA screening in hospitals and long-term care facilities.
• Public health surveillance of oxacillin resistance in clinical isolates.

3. Veterinary Diagnostics

• Testing of Staphylococcus pseudintermedius and other animal-origin isolates for oxacillin resistance.

4. Pharmaceutical and Research Applications

• Validation of oxacillin susceptibility profiles for new antimicrobial formulations or resistance mechanism studies.

Use Instructions

1. Preparation of Media:
   • Use Mueller-Hinton Agar supplemented with 2% NaCl (for optimal expression of resistance).
   • For borderline isolates, consider incubation with CO₂ for enhanced detection.
2. Inoculum:
   • Adjust bacterial suspension to 0.5 McFarland turbidity standard.
3. Inoculation:
   • Swab uniformly over agar surface.
4. Disc Application:
   • Apply 1 µg or 5 µg Oxacillin disc using sterile forceps or a disc dispenser.
5. Incubation:
   • 35 ± 2 °C for 24 hours in ambient air or CO₂ as specified.
6. Result Interpretation:
   • Measure inhibition zones and interpret according to CLSI M100 or EUCAST breakpoint tables.
   • Confirm borderline resistance with cefoxitin disc or mecA gene PCR, if necessary.

Technical Specifications

Quality Control

Each batch is QC-tested with control strains to ensure disc performance:

Liofilchem® Oxacillin OX Discs (1 µg, 5 µg) are an essential diagnostic tool for accurate and reliable detection of oxacillin resistance in Staphylococcus spp., especially MRSA. With optimized formulations for both clinical and veterinary applications, these discs ensure reproducible results across laboratories. Trusted by microbiologists worldwide, they are indispensable for effective infection control and resistance surveillance.