MARTIN LEWIS AGAR

Technical Data #1357a / 2013.05.07

Martin Lewis Agar is a selective and enriched medium for the isolation and cultivation of Neisseria sp. from mixed flora. Hemoglobin, Bio-X and dextrose are replacing lysed heated blood to give to the culture media enough nutrients agents to permit luxuriant growth of fastidious microorganisms. Antibiotics inhibit normal flora growth as yeasts, gram-positive and gram-negative bacteria. Trimethoprim lactate prevents Proteus swarming.

 


 

FORMULA
in grams per liter purified filtered water

Casein Peptone

7,5

Meat Peptone

7,5

Corn Starch

1,0

Potassium Phosphate, dibasic

4,0

Potassium Phosphate, monobasic

1,0

Sodium Chloride

5,0

Agar

10,0

Hemoglobin

10,0

Dextrose

1,5

Enrichment Bio-X

10 ml

Antibiotics V.C.A.T

10 ml

pH 7,2 +/- 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 36 g of dehydrated media in 500 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. Add 500 ml of sterile 2% Hemoglobin (8662), 10 ml of Bio-X Enrichment (8601) and 10 ml of V.C.A.T. (8620). Mix gently and 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 with 5% CO2 for 48 hours.


QUALITY CONTROL

Results after 48hrs at 35C w/ CO2

Organisms

ATCC

Growth

Neisseria gonorrheae

43069

+

Neisseria gonorrheae

clinical

+

Neisseria meningitidis

13090

+

Neisseria sicca

9913

-

Staphylococcus epidermidis

12228

- or partial

Escherichia coli

25922

- or partial

Candida albicans

60193

- or partial

Proteus mirabilis

43071

- or partial

On Martin Lewis Agar, Neisseria gonorrheae colonies are small, colorless to grayish. Neisseria meningitidis are larger, bluish-gray.


LIMITATIONS OF METHOD
Some strains of Neisseria gonorrheae may be inhibited by vancomycin and some by trimethoprim lactate. An enriched general purpose enriched medium as Chocolate Agar should be inoculated at the same moment. This medium is only a part of the identification. Other tests may be required.


REFERENCES

  1. 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.
  2. N.C.C.L.S. 1990 Quality Assurance for Commercially Prepared Microbiological Culture Media. Approved Standard. Vol.10, No.14. NCCLS Document M22-A.
  3. Mac Faddin, Jean F., 1985 Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria. Vol.1. Baltimore, MD.: Williams & Wilkins.
  4. Martin, J.E., T.E. Billings, J.F. Hackney, J.D. Thayer 1967 Primary isolation of N. gonorrheae with a new commercial medium. Public Health Rep. 82:361-363.
  5. Thayer, J.D., Improved medium selective for cultivation of N. gonorrheae and N. meningitidis. Pub. Health. Rep. 81:559-562


CATALOGUE NUMBERS

Dehydrated media 500 g QB-39-1906
Hemoglobin 500 g QB-39-2114
     
Prepared media    
Plates, 100x15 mm 10/pkg 1357
Mono-Plates, 100x15 mm 10/pkg 1357M
Bi-plate: Choco/Martin Lewis, 100x15 mm 10/pkg 1457
     
Bio-X Enrichment, 10 ml 10/pkg 8601
Hemoglobin, 2% sterile 500 ml 8662

 


 

 

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