Cat. no. C6120 CRITERION™ MacConkey Agar without Crystal Violet 104gm
Cat. no. C6121 CRITERION™ MacConkey Agar without Crystal Violet 500gm
Cat. no. C6122 CRITERION™ MacConkey Agar without Crystal Violet 2kg
Cat. no. C6123 CRITERION™ MacConkey Agar without Crystal Violet 10kg
Cat. no. C6124 CRITERION™ MacConkey Agar without Crystal Violet 50kg


Hardy Diagnostics CRITERION™ MacConkey Agar without Crystal Violet is recommended for the detection of coliforms and enteric pathogens in water, waste water, and foods, as well as for differentiating Mycobacterium spp.

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.


CRITERION™ MacConkey Agar without Crystal Violet is a modification of the formula originally developed by MacConkey in 1905.(11) The modified medium contains a higher concentration of bile salts and does not contain crystal violet. The exclusion of crystal violet renders the medium less selective than the original formula and permits growth of staphylococci, enterococci, mycobacteria, and the Enterobacteriaceae.

The selective/differential characteristics of the medium make it useful in determining the fecal contamination of food and water. Lactose-fermenting microorganisms produce pink to red colored colonies while non-lactose-fermenters appear colorless.

The medium is especially useful in differentiating Mycobacterium fortuitum-chelonae complex from other rapidly growing acid-fast bacilli.(1-3) Common saprophytic species of acid-fast bacilli are inhibited on the medium while the potentially pathogenic rapid growers of the Mycobacterium fortuitum-chelonae complex grow within 5-11 days and usually produce a color change in the medium.


Gram weight per liter: 52.0gm/L
Pancreatic Digest of Casein 10.0gm
Peptic Digest of Animal Tissue 10.0gm
Lactose 10.0gm
Bile Salts No. 3 5.0gm
Sodium Chloride 5.0gm
Neutral Red 30.0mg
Agar 12.0gm

Final pH 7.4+/- 0.2 at 25ºC.

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


Store the sealed bottle(s) containing dehydrated culture medium at 2-30ºC. 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 it is not free-flowing or if the color has changed from its original beige.

Store the prepared culture media at 2-8ºC.



1. Suspend 52.0gm of the dehydrated culture media in 1 liter of distilled or deionized water.

2. Heat to boiling and mix to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

4. Dispense into sterile containers as desired.


For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. G99.


Most gram-positive microorganisms, with the exception of fecal streptococci and some staphylococci, are inhibited on MacConkey Agar without Crystal Violet.

Approximately 25% of M. smegmatis strains grown on MacConkey Agar without Crystal Violet.(5) The 3-day arylsulfatase test may be performed to aid in the differentiation of M. smegmatis (arylsulfatase-negative) from mycobacteria belonging to the M. fortuitum-chelonae complex (arylsulfatase-positive).(5)

M. fortuitum may or may not produce a color change in the medium, however the extent of growth is more important than the development of a color change.


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


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Escherichia coli
ATCC ® 25922
A 24hr 35°C Aerobic Growth; pink to red colonies
Proteus mirabilis
ATCC ® 12453
A 24hr 35°C Aerobic Growth; clear colonies
Enterococcus faecalis
ATCC ® 29212
A 24hr 35°C Aerobic Growth; clear colonies

User Quality Control


CRITERION™ MacConkey Agar without Crystal Violet powder should appear homogeneous, free-flowing, and beige in color. The prepared media should appear clear, and reddish-orange in color.


1. Gordon, R.E. and Mihm, J.M 1959.. J. Gen. Microbiol.; 21:736-748.

2. Kubica, G.P. 1973. Amer. Rev. Resp. Dis.; 107:9-21.

3. Kubica, G.P. and Vitvitsky, J. 1974. Trudeau Institute, Inc. Saranac Lake, N.Y., Applied Microbiology; 917-919.

4. Kent, P.T. and Kubica, G.P. 1985. Public Health Mycobacteriology, U.S. Dept. of Health and Human Services, Public Health Service, Center for Disease Control, Atlanta, GA.

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

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

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

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

9. 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.

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

11. MacConkey, A.T. 1905. J. Hyg.; 5:333.

ATCC is a registered trademark of the American Type Culture Collection.