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 ?
029 * Values along the same column-for each media with different superscripts are significantly different at different storage times, NA= Nutrient agar, MCA= MacConkey agar, CHA= Chocolate agar Table 5: Characterization and identification of micro-organisms Sample NA MCA CHA Gram +ve -ve +ve Motility -ve +ve -ve Catalase +ve +ve -ve Coagulase +ve -ve -ve Indole Test -ve +ve NT Oxidase sugar -ve -ve -ve Glucose +ve +ve +ve Sucrose +ve +ve +ve Maltose +ve +ve -ve Lactose +ve +ve +ve Arabinose -ve -ve -ve Mannitose +ve +ve +ve Sorbitose -ve -ve -ve Urease +ve -ve - Staphylococcus Escherichia Enterococcusa aureus Coli Faecalis NA = Nutrient agar, MCA = MacConkey agar, CHA = Chocolate agar
2) Nonstandard abbreviations: STEC, shiga toxin-producing Escherichia coli; SMAC, MacConkey agar with sorbitol.
100 [micro]l of the diluted sample was plated on STAA agar, Plate Count Agar, Sorbitol MacConkey agar, Violet Red Bile Glucose agar, APT agar and the PS agar.
Each isolate was streaked for isolation onto MacConkey agar and incubated at 35[degrees]C for one to two days.
Non-lactose fermenting colonies were observed on MacConkey agar within 24 hours (Oxoid, England).
coli O157:H7 counts were determined on sorbitol MacConkey agar.
coli enrichment broth and sorbitol MacConkey agar (SMAC), a selective medium used to screen for STEC serotype O157:H7 because this serotype, unlike most E.
In the second part of this experiment, 1 mL of each sample was placed onto a MacConkey agar plate and an antibiotic disk was placed in the center of each plate.
The sensitivity of 98% and specificity of 97% for the MacConkey agar paddle are based on 10,000 organisms per milliliter compared with the "gold standard" of 100,000 organisms per milliliter using a platinum loop and sheep agar culture.
The suspected colonies so obtained were streaked on Blood Agar (BA) and MacConkey Agar (MA).
The stool sample was inoculated on MacConkey agar (Oxoid, UK) and xylose lysine decarboxylase agar (XLD) (Oxoid, UK).