MacConkey Agar (Dehydrated) | CM0007B

MacConkey Agar (Dehydrated) | CM0007B

Detect, isolate and enumerate coliforms and intestinal pathogens in water, dairy products and biological specimens with Thermo Scientific™ Oxoid™ MacConkey Agar (Dehydrated). This differential medium gives a number of diagnostic indications such as bile tolerance, colony morphology and chromogenesis. MacConkey Agar corresponds to the medium recommended by the World Health Organizaton¹, the Department of Health² for the bacterial examination of water.

Use MacConkey Agar for the cultivation of pathogens which may be present in a variety of specimens.

• Easy-to-read: easy to differentiate Escherichia coli (red non-mucoid colonies) from Staphylococcus spp. (pale pink opaque colonies) and Pseudomonas aeruginosa (green-brown) colonies.
• Recommended by World Health Organizaton¹, the Department of Health².

Typical Formula*
Peptone  20.0
Lactose   10.0
Bile salts  5.0
Sodium chloride  5.0
Neutral red  0.075
Agar  12.0
* adjusted as required to meet performance standards

Directions
Suspend 52g in 1 litre of distilled water. Bring to the boil to dissolve completely. Sterilize by autoclaving at
121°C for 15 minutes. Cool to 50°C. Mix well and pour into sterile Petri dishes.
Physical Characteristics
Straw/pink, free-flowing powder
Colour on reconstitution - dark red
Moisture level - less than 7%
pH 7.4 ± 0.2 at 25°C
Clarity - clear
Gel strength - firm, comparable to 12.0g/litre of agar

Microbiological Tests Using Optimum Inoculum Dilution
Control Medium: Tryptone Soya Agar
Reactions after incubation at 37°C for 18-24 hours
Medium is challenged with 10-100 colony-forming units
Salmonella typhimurium ATCC® 14028 1-3mm straw colonies
Salmonella nottingham NCTC 7832 1-3mm straw colonies
Shigella flexneri ATCC® 12022 1-4mm straw colonies
Klebsiella pneumoniae ATCC® 29665 1-3mm red/pink, mucoid colonies
Pseudomonas aeruginosa ATCC® 27853 1-3mm straw colonies
Escherichia coli ATCC® 25922 1-2mm pink/red colonies
Proteus mirabilis ATCC® 29906 1-2mm straw colonies, no swarming
Enterococcus faecalis ATCC® 29212 0.5-1mm red colonies
Staphylococcus aureus ATCC® 25923 0.5-1mm pink colonies
A satisfactory result is represented by recovery of positive strains equal to or greater than 70% of the control
medium.