MANNITOL SALT AGAR

Technical Data #1858a / 2013.06.15

Mannitol Salt Agar is a selective and differential solid medium used for the isolation of pathogenic staphylococci. Addition of sodium chloride, ten times the usual concentration, inhibits most organisms but staphylococci. Mannitol fermentation by Staphylococcus aureus results in opaque colonies surrounded by a yellow zone.

 


 

FORMULA
in grams per liter purified filtered water

Casein Peptone

5,0

Meat Peptone

5,0

Beef Extract

1,0

D-Mannitol

10,0

Sodium Chloride

75,0

Phenol Red

0,025

Agar

15,0

pH 7.4 +/- 0,2 25 C

This approximate formula may be adjusted and/or enriched to obtain best results.


PRECAUTIONS
This medium is for IN VITRO diagnostic use only.


STORAGE
Store prepared media at 2-8 C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25 C.


SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.


DIRECTIONS
Suspend 111 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterilize at 121 C for 15 minutes. Cool to 45-50 C and mix gently. Dispense into sterile Petri dishes.


PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

  1. Directly, inoculate plate as soon as possible with specimen and streak for isolation.
  2. Incubate at 35 C for up to 48 hours.
  3. Examine after 24 and 48 hours.


QUALITY CONTROL

Results after 48 hrs at 35C

Organisms

ATCC

Growth

Colour

Staphylococcus aureus

25923

+

yellow

Staphyloccoccus epidermidis

12228

+

red

Proteus mirabilis

12453

- or partial

colorless

Colonies of S. aureus will appear on Mannitol Salt Agar as large, opaque surrounded by yellow zone in medium. Enterococci may grow and ferment mannitol but colonies appear as pinpoint.


LIMITATIONS OF METHOD
This medium is only a part of the identification. Other tests may be required.


REFERENCES

  1. N.C.C.L.S. Quality Assurance for Commercially prepared Microbiological Culture Media. N.C.C.L.S. Publication M-22-A Approved Standard 1990 Vol. 10 No.14.
  2. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American society for Microbiology.
  3. Mac Faddin, Jean F., Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria Vol.1 1985 Baltimore, MD. Williams & Wilkins.
  4. Chapman, G.H. 1945 The significance of sodium chloride in studies of staphylococci. J. Bacteriol. 50:201-203.


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-2906
     
Prepared media    
Plates, 100x15 mm 10/pkg 1858
Mono-Plates, 100x15 mm 10/pkg 1858M

 


 

 

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