Mannitol Salt Agar

Mannitol Salt Agar

$22.00 – $190.00

100 g, 500g, 2 kg
Number of sizes: 3
Type: Powder

Dehydrated Powder

No sub-products available for this product.

SKU: MSA-G Category:

Description

Intended Use and Principle of Procedure
This medium conforms with specifications of The United States Pharmacopeia (USP). Mannitol Salt Agar is used for the selective isolation and enumeration of staphylococci from clinical and nonclinical materials.

 

Mannitol Salt Agar is a nutritive medium due to its content of peptones and beef extract, which supply essential growth factors, such as nitrogen, carbon, sulfur and trace nutrients. The 7.5% concentration of sodium chloride results in the partial or complete inhibition of bacterial organisms other than staphylococci. Mannitol fermentation, as indicated by a change in the phenol red indicator, aids in the differentiation of staphylococcal species.

 

Summary and Explanation
Koch, in 1942, reported that only staphylococci grow on agar media containing 7.5% sodium chloride.1 Chapman further studied this phenomenon in greater detail and concluded that the addition of 7.5% sodium chloride to phenol red mannitol agar results in an improved medium for the isolation of plasmacoagulating staphylococci.2 This medium is listed as one of several recommended for the enumeration of gram-positive bacteria in cosmetics3 and is recommended in the USP for use in the performance of Microbial Limit Tests.

 

Formulae
 

Proteose Peptone No. 3 10.0g
Beef Extract 1.0g
D-Mannitol. 10.0g
Sodium Chloride 75.0g
Agar 15.0g
Phenol Red 25.0mg

 

Procedure
Use standard procedures to obtain isolated colonies from specimens. Incubate plates for 24-48 hours at 35 ± 2°C in an aerobic atmosphere.

 

Directions for Preparation from Dehydrated Product
1. Suspend 111 g of the powder in 1 L of purified water. Mix thoroughly.

2. Heat with frequent agitation and boil for 1 minute to completely dissolve the powder.

3. Autoclave at 121°C for 15 minutes.

4. Test samples of the finished product for performance using stable, typical control cultures.

 

Identification Specification and Cultural Response
 

Dehydrated Appearance: Light pink, free-flowing, homogeneous.
 

 

Prepared Appearance:

 

 

Solution:

  

 

Pinkish red, slightly opalescent.

 

11.1% solution, soluble in purified water upon boiling. Solution is red, slightly opalescent.
 

pH:

 

 7.4 ± 0.2
Cultural Response: 

 

 Prepare the medium per label directions. Inoculate and incubate at 35 ± 2°C for 18-24 hours or up to 48 hours. A yellow zone around the colony indicates mannitol has been fermented.
Reaction 11.1%
Solution 25°C

 

 

Microorganism ATCC CFU Recovery
Enterobacter aerogenes 13048 103 Marked to complete inhibition
Escherichia coli 25922 102 Marked to complete inhibition
Proteus mirabilis 12453 102 Partial inhibition
Staphylococcus aureus 25923 102-2×102 Good
Staphylococcus epidermidi 12228 102-2×102 Good

 

Expected Results
Typical colonial morphology on Mannitol Salt Agar is as follows:

Staphylococcus aureus …………………… Small to large with yellow zones

Staphylococci other than S. aureus…….. Small to large with red zones

Streptococci ………………………………….. No growth to trace growth

Micrococci ……………………………………. Large, white to orange

Gram-negative bacteria …………………… No growth to trace growth

 

References
1. Koch. 1942. Zentralbl. Bakteriol. Parasitenkd. Abt. I Orig. 149:122.

2. Chapman. 1945. J. Bacteriol. 50:201.

3. Hitchens, Tran and McCarron. 1995. FDA bacteriological analytical manual, 8th ed. AOAC International, Gaithersburg, Md.

4. United States Pharmacopeial Convention, Inc. 2001. The United States pharmacopeia 25/The national formulary 20 – 2002. United States Pharmacopeial Convention, Inc., Rockville, Md.

Additional information

Size

100g, 500g, 2kg

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