MacConkey agar

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Mac·Con·key a·gar

medium containing peptone, lactose, bile salts, neutral red, and crystal violet, used to identify gram-negative bacilli and characterize them according to their status as lactose fermenters. Fermenters appear as pink colonies whereas nonfermenters are colorless.

MacConkey agar

A differential and selective growth medium used to isolate and identify gram-negative bacilli, often enteric pathogens, based on fermentation or lack of fermentation of a sugar added to the media. MA is peptone-based and contains bile salts and crystal violet (which inhibit the growth of gram-positive organisms), a sugar (usually lactose) and a pH indicator, allowing differentiation of lactose-fermenting (indicated by pink colonies, e.g., Escherichia coli) and non-lactose-fermenting (colourless colonies, e.g., Proteus mirabilis) bacteria.

Mac·Con·key agar

(mă-kongk'ē ā'gahr)
Medium containing peptone, lactose, bile salts, neutral red, and crystal violet; used to recover gram-negative bacilli and characterize them according to their ability to ferment lactose. Fermenters appear as red colonies, whereas nonfermenters are colorless.


Alfred Theodore, English bacteriologist, 1861-1931.
MacConkey agar - a medium used to identify gram-negative bacilli and characterize them according to their status as lactose fermenters. Synonym(s): MacConkey medium
MacConkey medium - Synonym(s): MacConkey agar


a dried hydrophilic, colloidal substance extracted from various species of red algae. When suspended in a liquid medium and heated to 212°F (100°C), the agar dissolves. When it is allowed to cool to 110°F (43°C) the medium becomes a solid gel. It is used in culture media for bacteria and other microorganisms, in making emulsions, and as a supporting medium for immunodiffusion and immunoelectrophoresis. Because of its bulk it is also used in medicines to promote peristalsis and relieve constipation.

birdseed agar
one containing Guizotia abyssinicia (Niger) seed and creatinine, used for growing Cryptococcus neoformans. Called also Niger agar.
bismuth sulfite agar
a special preparation used for isolation of salmonellae from food.
blood agar
a culture medium used for the growth of bacteria. Consists of agar and intact erythrocytes.
brain heart infusion agar
used for cultivating the yeast phase of dimorphic fungi.
brilliant green agar
used to cultivate salmonellae.
chocolate agar
an enriched agar for the growth of Hemophilus, some Actinobacillus, and Taylorella spp. A molten agar and blood mixture is held at 122°F (50°C) prior to pouring plates. The additional nutrients supplied are hemin and NAD.
agar diffusion test
see antimicrobial sensitivity test.
eosin-methylene blue (EMB) agar
used for the identification of Eschericha coli.
agar gel immunodiffusion test
see immunodiffusion tests.
MacConkey agar
contains bile salts, lactose and neutral red indicator for isolation of enterobacteria.
mannitol salt agar
selective for staphylococci.
milk agar
contains skim milk and used to demonstrate casein digestion.
Niger seed agar
see birdseed agar (above).
nutrient agar
the basic growth medium for bacteria, composed of beef extract and peptone.
potato dextrose agar
used in cultivating fungi; promotes sporulation and pigmentation.
Sabouraud's dextrose agar
one used for isolation of fungi. See also dermatophyte test medium.
agar sausage
see medium sausage.
xylose lysine (XLD) agar
used to differentiate Enterbacteriaceae.
References in periodicals archive ?
LB-MW: Luria Broth in marine water, LB-DW: Luria Broth in distilled water, TSA-MW: Trypticase soy agar in marine water, TSA-DW: Trypticase soy agar in distilled water, McConkey-MW: McConkey agar in marine water, McConkey-DW: McConkey agar in distilled water, CECC-MW: Chromagar E.
UTI was diagnosed urine cultures with Nutrient agar, Blood agar plates and McConkey agar using a calibrated loop (0.
Swabs from ocular discharges were collected aseptically from each bird and cultured on 10% ovine blood agar and McConkey agar by incubating at 37[degrees]C for 48 hrs under aerobic conditions.
The strain did not grow on McConkey agar and was facultatively anaerobic.