CRITERION™ A-1 MEDIUM

Cat. no. C7570 CRITERION™ A-1 Medium 63gm
Cat. no. C7571 CRITERION™ A-1 Medium 500gm
Cat. no. C7572 CRITERION™ A-1 Medium 2kg
Cat. no. C7573 CRITERION™ A-1 Medium 10kg
Cat. no. C7574 CRITERION™ A-1 Medium 50kg

INTENDED USE

Hardy Diagnostics CRITERION™ A-1 Medium is recommended for the detection of fecal coliforms in foods, treated wastewater, and seawater.

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.

SUMMARY

Enumeration of coliform organisms, specifically E. coli, has been used since the early 1900's to determine water purity. Rapid detection is of great importance from a public health standpoint. One of the limiting factors in using E. coli is the length of time required for complete identification. In 1972, Andrews and Presnell reported on the development of A-1 Medium, which was capable of E. coli recovery from estuarine water in 24 hours instead of 72 hours. E. coli was recovered in greater numbers and the broth did not require a preenrichment step.(1) They were able to confirm its productivity and determined that recovery was faster and the occurrence of false-positives was substantially reduced when compared to the APHA method.(2,3)

FORMULA

Gram weight per liter: 31.5gm/L
Pancreatic Digest of Casein 20.0gm
Lactose 5.0gm
Sodium Chloride 5.0gm
Salicin 0.5gm
Triton ® X-100 1.0ml

Final pH 6.9 +/- 0.2 at 25ºC.

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

STORAGE AND SHELF LIFE

Store the sealed bottle(s) containing dehydrated culture medium at 2-30 degrees C. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if the color has changed from its original light beige.

Store the prepared media at 2-30ºC. away from light.

PRECAUTIONS

METHOD OF PREPARATION FOR DEHYDRATED CULTURE MEDIA

1. Suspend 31.5gm of the dehydrated culture media in 1 liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat as necessary to dissolve completely.

3. Dispense into tubes containing inverted durham tubes.

4. Autoclave at 121ºC. for 10 minutes.

PROCEDURE AND INTERPRETATION OF RESULTS

For further information on procedures and interpretation of results, consult listed references.

LIMITATIONS

Some strains may fail to grow or grow poorly on this medium due to varying nutritional requirements.

Fecal coliform counts are usually greater than E. coli counts.

Interpretation of test procedure using A-1 Medium requires understanding of the microflora of the specimen.

MATERIALS REQUIRED BUT NOT PROVIDED

Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.

QUALITY CONTROL

Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Enterobacter aerogenes
ATCC ® 13048
A 24hr 35°C Aerobic Growth with gas production
Escherichia coli
ATCC ® 25922
A 24hr 35°C Aerobic Growth with gas production
Bacillus subtilis
ATCC ® 6633
B 24hr 35°C Aerobic Inhibited

User Quality Control

PHYSICAL APPEARANCE

CRITERION™ A-1 Medium powder should appear non-free-flowing, and light beige in color. The prepared media should appear clear, and light to medium amber in color. Flocculent precipitate may be present.

REFERENCES

1. Andrews, W.H. and M.W. Presnell. 1972. Rapid recovery of Escherichia coli from estuarine water. Appl. Microbiol.; 23:521-523.

2. Eaton, A.D., L.S. Clesceri, and A.E. Greenberg. 1995. Standard Methods for the Examination of Water and Wastewater, 19th ed. American Public Health Association Inc., Washington, D.C.

3. Andrews, W.H., C.D. Diggs, and C.R. Wilson. 1975. Evaluation of a medium for the rapid recovery of Escherichia coli from shellfish. Appl. Microbiol.; 29:130-131.

4. 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.

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

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

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

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


ATCC is a registered trademark of the American Type Culture Collection.
Triton is a registered trademark of Union Carbide Chemicals & Plastics Technology Corp.

050916gr