Mannitol Salt Agar
Also known as：MSA · MS Agar · Chapman Agar · Mannitol Salt Phenol Red Agar · Chapman Medium
For the selective isolation and differentiation of Staphylococcus aureus from food, pharmaceutical products, and other materials, in accordance with the harmonized pharmacopoeias.
- Category
- Dehydrated Culture Media
- Dissolve per litre
- 111.03 g
- Pack sizes
- 500 g · 5 kg · 25 kg
- Certifications
- ISO 22000
Data updated：2026-11-06
Brand cross-reference：BD Difco Mannitol Salt Agar · Oxoid Mannitol Salt Agar · Merck Mannitol Salt Phenol-red Agar（USP <62>、FDA BAM） Brand cross-reference
Overview
Mannitol Salt Agar (MSA) is the classic selective and differential medium for staphylococci. Its 7.5% salt suppresses most bacteria so only salt-tolerant staphylococci grow; Staphylococcus aureus ferments mannitol and turns phenol red yellow, distinguishing it from non-fermenting S. epidermidis. Used to screen food, cosmetics and clinical samples for S. aureus.
Principle
Mannitol Salt Agar is based on the observation by Chapman that a high concentration of sodium chloride is tolerated by staphylococci but inhibits most other bacteria.¹ Pancreatic digest of casein, peptic digest of animal tissue, and beef extract supply nitrogen, amino acids, vitamins, and growth factors. Sodium chloride at 7.5% provides the selectivity of the medium. Mannitol is the fermentable carbohydrate, and phenol red serves as the pH indicator. Staphylococcus aureus ferments mannitol, producing acid that turns the colonies and the surrounding medium yellow, whereas most coagulase-negative staphylococci do not ferment mannitol and form small red to pink colonies with no change in the medium. The medium is specified in the harmonized pharmacopoeias for the detection of Staphylococcus aureus in non-sterile products.²
How selective media fit into the testing workflow
Pathogen testing normally runs in three stages: a pre-enrichment medium such as Buffered Peptone Water repairs injured cells and raises numbers, a selective enrichment then suppresses competing flora, and finally a selective differential agar isolates the target colonies. Selective agents are typically bile salts, dyes, or antibiotics; differential agents make target colonies develop a characteristic colour or morphology. Choose the combination specified by the method you follow.
Directions
Suspend 111 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
Cultural response
| Test organism | ATCC | Growth |
|---|---|---|
| Staphylococcus aureus | 6538 | good-luxuriant |
| Staphylococcus aureus | 25923 | good-luxuriant |
| Staphylococcus epidermidis | 12228 | good |
| Escherichia coli | 8739 | inhibited |
Product highlights
- Food-grade raw materials, produced in an ISO 22000 certified facility
- Manufactured to the standard formulation, 111.03 g per litre
- Performance verified against standard control strains before release (Staphylococcus aureus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli)
- Available in 500 g / 5 kg / 25 kg, from laboratory to industrial scale
- COA, specification sheet, and technical data sheet available; samples on request
- Manufactured in Taiwan with reliable supply
Food grade versus laboratory grade
Most culture media suppliers use laboratory-grade raw materials, which are held to lower standards for heavy metal residues, microbial contamination control, and traceability. That is adequate for pure research but not for applications with stricter raw-material requirements. STBIO manufactures with food-grade raw materials throughout, in a facility certified to ISO 22000 food safety management.
- Food microbiology laboratories working to ISO 17025 or equivalent requirements
- Biotech manufacturers exporting fermentation products and needing full raw-material traceability
- Organisations with ESG or compliance audit requirements across their supply chain
- Companies sourcing both Halal and non-Halal products who need one consistent material grade
Frequently asked questions
01Can selective media be autoclaved?
Not always. Some media containing dyes or selective inhibitors lose their selectivity if overheated and should only be heated until fully dissolved, without autoclaving. Follow the preparation instructions for this product, and contact us if you are unsure.
02How much powder per litre?
Use 111.03 g per litre of deionised water; preparation and sterilisation conditions are given on the specification sheet.
03Which organisms is it suitable for?
Pathogens, Gram-positive, S. aureus, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli. See the cultural response table and the specification sheet.
04What are the equivalent brand products and standard methods?
Cross-reference: BD Difco Mannitol Salt Agar, Oxoid Mannitol Salt Agar, Merck Mannitol Salt Phenol-red Agar. Standard methods: USP <62>, FDA BAM. Formulations may differ slightly between makers; refer to the specification sheet.
05Can it be used for food-grade applications?
Yes. It is made from food-grade raw materials in an ISO 22000 certified facility and is suitable for culturing starters for fermented products that are consumed directly.
06How is this product prepared?
Suspend 111 g of powder in 1 L of purified water. Heat with continuous stirring and bring to the boil for 1 minute. Sterilize by autoclaving at 121°C for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates. Test the finished medium for performance using stable, standard control cultures.
07Is there a Halal certified version of this product?
Yes. This is the standard version; a Halal certified version is also produced from food-grade raw materials with Halal documentation, for compliant sourcing in Malaysia, Indonesia, and the Middle East.
08How do I request a bulk quotation, and can you provide a COA?
Yes. This product is available in 500 g, 5 kg, 25 kg. Tell us your application and volume when requesting a quotation; we reply within one working day and can supply the COA, specification sheet, and technical data sheet.
Used in these applications
References
- 1. Chapman G. H., 1945. The significance of sodium chloride in studies of staphylococci. J. Bacteriol., 50:201-203.
- 2. United States Pharmacopeia, current edition. Chapter <62> Microbiological Examination of Nonsterile Products: Tests for Specified Microorganisms, USP-NF, Rockville, MD.