Wilkins-Chalgren Media

Cat. no. G89 Wilkins-Chalgren Agar, 15x100mm Plate, 18ml 10 plates/bag

INTENDED USE

Hardy Diagnostics Wilkins-Chalgren Agar is recommended for the cultivation and isolation of anaerobic microorganisms and for the preparation of agar dilution tests. (3,5,10)

SUMMARY

Anaerobic bacteria of clinical significance are known to cause a variety of human infections, including endocarditis, meningitis, wound infections, and bacteremia. Their successful culture is dependent upon strict adherence to their atmospheric requirements, nutritional needs, and appropriate collection and culture constraints. (2,4,7,8) Wilkins-Chalgren Agar was established by Wilkins and Chalgren in the mid 1970s as a standard medium for use in determining the minimal inhibitory concentration (MIC) of antibiotics used for anaerobic bacteria by the agar dilution method. The medium was developed to support the growth of most clinically isolated anaerobic microorganisms, without the addition of blood. More recent editions of the CLSI (formerly NCCLS) standard reference method for antimicrobial susceptibility testing of anaerobic bacteria have replaced this medium with the Wadsworth method. (6)

Wilkins-Chalgren Agar contains yeast extract to supply essential vitamins, purines, and pyrimidines to enhance the growth of Prevotella melaninogenica , and sodium pyruvate to support the growth of Peptostreptococcus anaerobius and assacharolytic organisms such as Veillonella spp. Arginine is added to improve the growth of Eubacterium lentum . Dextrose is added as an energy source. Hemin and vitamin K support the growth of organisms in the Bacteroides fragilis group, along with Prevotella melaninogenica . Sodium chloride is an isotonic agent and agar is the solidifying agent. (2,4,7,8)

FORMULA

Ingredients per liter of deionized water:*

Enzymatic Digest of Casein 10.0gm
Enzymatic Digest of Gelatin 10.0gm
Yeast Extract 5.0gm
Sodium Chloride 5.0gm
Dextrose 1.0gm
L-Arginine 1.0gm
Sodium Pyruvate 1.0gm
Hemin 0.005gm
Vitamin K 0.0005gm
Agar 15.0gm

Final pH 7.1 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.

STORAGE AND SHELF LIFE

Storage: Upon receipt store at 2-8ºC. away from direct light. Media should not be used if there are any signs of deterioration (shrinking, cracking, or discoloration), contamination, or if the expiration date has passed. Product is light and temperature sensitive; protect from light, excessive heat, moisture, and freezing.

PRECAUTIONS

PROCEDURE

For a complete discussion on standard methods for testing anaerobic microorganisms, refer to the appropriate procedures as documented in the references. (3-6,8-10)

INTERPRETATION OF RESULTS

Refer to the Wadsworth-KTL Anaerobic Bacteriology Manual or other texts for more information on identification of anaerobes. (6)

LIMITATIONS

In vitro susceptibility does not necessarily imply in vivo effectiveness.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as loops, swabs, applicator sticks, other culture media, incinerators, and incubators, etc., as well as serological and biochemical reagents, are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Bacteroides fragilis
ATCC ® 25285**
A 40-48hr 35°C Anaerobic Growth
Bacteroides levii
ATCC ® 29147
A 40-48hr 35°C Anaerobic Growth
Clostridium perfringens
ATCC ® 13124**
A 40-48hr 35°C Anaerobic Growth

** Recommended QC strains for User Quality Control according to the CLSI document M22 when applicable.

USER QUALITY CONTROL

Physical Appearance

Wilkins-Chalgren Agar should appear clear with a slight opalescence, and light amber in color.

REFERENCES

1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

3. Hanson, C.W. and W.J. Martin. 1978. Modified Agar Dilution Method for Rapid Antibiotic Susceptibility Testing of Anaerobic Bacteria. Antimicro. Agents Chemother.; 13(3):383-388.

4. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

5. Jones, R.N., P.C. Fuchs, C. Thornsberry, and N. Rhodes. 1978. Antimicrobial Susceptibility Tests for Anaerobic Bacteria. Comparison of Wilkins-Chalgren Agar Reference Method and a Microdilution Method, and Determination of Stability of Antimicrobics Frozen in Broth. Current Microbio.; Vol. 1:81-83.

6. Jousimies-Somer, H.R., S.P. Citron, D. Baron, E.J. Wexler, and H.M. Finegold. 2002. Wadsworth-KTL Anaerobic Bacteriology Manual, 6th ed. Star Publishing Company, New York, N.Y.

7. Koneman, E.W., et al. Color Atlas and Textbook of Diagnostic Microbiology, J.B. Lippincott Company, Philadelphia, PA.

8. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

9. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.

10. Zabrinsky, R.J. and K.J. Hauser. 1977. Stability of Antibiotics in Wilkins-Chalgren Anaerobic Susceptibility Testing Medium After Prolonged Storage. Antimicro. Agents Chemother.; 12(3):440-441.


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041816gr