Product Overview
This Mannitol Salt Agar Plate is a ready-to-use, selective and differential medium designed for the isolation and presumptive identification of Staphylococcus aureus from clinical, environmental, and food samples. The medium is based on the classical Chapman formulation, which relies on a high salt concentration (7.5% NaCl) to inhibit most non-staphylococcal organisms while allowing staphylococci to grow.
The differential property comes from D-mannitol and the pH indicator phenol red. Staphylococcus aureus ferments mannitol, producing acid that lowers the pH and causes the medium and colonies to turn yellow. Most coagulase-negative staphylococci (such as Staphylococcus epidermidis) do not ferment mannitol and produce pink to red colonies, allowing presumptive differentiation.
The 90mm format is suitable for streaking, swabbing, or air settle plate applications, and the triple vacuum packaging allows safe transfer into controlled environments.
Intended Use
- Selective isolation and presumptive identification of Staphylococcus aureus.
- Environmental monitoring in pharmaceutical, cosmetic, and food facilities.
- Hygiene monitoring of surfaces and personnel.
- Microbiological examination of raw materials and finished products.
- Educational and research laboratory use.
Composition (per Liter)
- Pancreatic Digest of Casein (Tryptone): 5.0 g
- Peptic Digest of Animal Tissue: 5.0 g
- Beef Extract: 1.0 g
- Sodium Chloride: 75.0 g
- D-Mannitol: 10.0 g
- Phenol Red: 0.025 g
- Agar: 15.0 g
- Final pH: 7.4 ± 0.2 at 25°C
Performance Characteristics
- Appearance: Red, smooth surface, free from cracks, visible impurities, and bubbles.
- Physicochemical: pH compliant; gel strength 500–650 g/cm².
- Sterility: No growth after incubation at 30–35°C for 2 days; no significant medium dehydration.
- Growth Promotion: Validated for robust growth with typical colony size and morphology for Staphylococcus aureus and Staphylococcus epidermidis; Escherichia coli is inhibited.
Interpretation of Results
- Yellow colonies with yellow halo: Presumptive Staphylococcus aureus (mannitol fermentation).
- Pink to red colonies with no color change: Presumptive coagulase-negative staphylococci (e.g., S. epidermidis).
- No growth or very poor growth: Indicative of inhibition of non-staphylococcal organisms.
Packaging and Storage
- Format: 90mm × 10 plates per pack.
- Fill Volume: 20–25 mL per plate.
- Packaging: Three-layer vacuum packaging for controlled environment transfer.
- Shelf Life: 30 days from date of manufacture.
- Storage: Store at 2–8°C, protected from light. Do not freeze.
