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 ?
coli O157:H7 isolation is plating of the specimen to a selective agar, such as MacConkey agar with sorbitol (SMAC).
It is a small gram-negative bacillus and facultative anaerobe that usually grows well on sheep blood (nonhemolytic), chocolate, and MacConkey agars.
Direct streaking was done, that is, when post mortem was carried out, a bacteriological loop was passed on the heart of the birds and was streaked onto the MacConkey agar which was incubated at 37[degrees]C for 18-24 hours.
A further subsample of eight colonies was obtained on MacConkey agar plates from sampling of all surfaces except the water fountain drains.
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
No growth was noted on any of the MacConkey agar plates.
Lactose-fermenting or -nonfermenting colonies of different morphology were collected from MacConkey agar and Brilliance ESBL Agar and screened for ESBL production by disk diffusion by using cefpodoxime (10 [micro]g), aztreonam (30 [micro]g), ceftazidime (30 [micro]g), cefotaxime (30 [micro]g), and ceftriaxone (30 [micro]g) disks (Oxoid) and confirmed by microdilution test according to Clinical Laboratory Standards Institute (CLSI) methods (12) by using Micronaut-S [beta]-lactamase V test plates (Merlin Diagnostika, Bornheim-Hersel, Germany).
Swabs were streaked onto 7% sheep blood agar (Oxoid Ltd, Hampshire, England), MacConkey agar (Oxoid), Sabouraud dextrose agar (Oxoid), Campylobacter selective agar, and Brucella selective agar plates.
coli 0157 culture, including modified Tryptone Soy Broth (mTSB), Sorbitol MacConkey Agar (SMAC) and Cefixime Tellurite MacConkey Agar (CT-SMAC), selective differential media for the isolation of E.
Following incubation, aliquots from the cultured positive tubes were aseptically streaked on MacConkey agar (Oxoid CM7) for total coliform and Eosin Methylene Blue agar [EMB (Oxoid CM69)] for faecal coliform and incubated at 37[degrees]C and 44[degrees]C, respectively.
modified Hodge test on Mueller-Hinton agar (MHT-MHA) (3), modified Hodge test on MacConkey agar (MHT-MCA) (4), imipenem-ethylenediaminetetraacetic acid + sodium mercapto acetic acid double disc synergy test (IPM-EDTA+SMA DDST) (3), combined disc test (CDT) (5), extended EDTA disc synergy test (eEDST) (6) and EDTA-IPM microbiological assay (EIM) (6).
They run an ELISA test for Shiga toxins; they do not grow it on MacConkey agar with sorbitol.