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Micro-culture-2

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medmaestro's version from 2015-11-03 05:05

SELECTIVE MEDIA

Mediaorganism
• Eosin methylene blue (EMB)contains dyes that are toxic for Gram positive bacteria and bile salt which is toxic for Gram negative bacteria other than coliforms. EMB is the selective and differential medium for coliforms
• YM (yeast and mold) which has a low pHdeterring bacterial growth
• MacConkey agarfor Gram-negative bacteria
• Hektoen enteric agar (HE)which is selective for Gram-negative bacteria
• Mannitol salt agar (MSA)which is selective for Gram-positive bacteria and differential for mannitol
• Terrific Broth (TB)is used with glycerol in cultivating recombinant strains of Escherichia coli.
• Xylose lysine desoxycholate (XLD) which is selective for Gram-negative bacteria
• Buffered charcoal yeast extract agar which is selective for certain gram-negative bacteria, especiallyLegionella pneumophila
• Baird–Parker agarfor Gram-positive Staphylococci
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DIFFERENTIAL MEDIA

Mediaorganism
• Blood agar(used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic Streptococcus
• Eosin methylene blue (EMB)which is differential for lactose fermentation
• MacConkey (MCK)which is differential for lactose fermentation
• Mannitol salt agar (MSA)which is differential for mannitol fermentation
• X-gal plateswhich are differential for lac operon mutants
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Transport media
Transport media should fulfill the following criteria:
• temporary storage of specimens being transported to the laboratory for cultivation.
• maintain the viability of all organisms in the specimen without altering their concentration.
• contain only buffers and salt.
• lack of carbon, nitrogen, and organic growth factors so as to prevent microbial multiplication.
• transport media used in the isolation of anaerobes must be free of molecular oxygen.
TRANSPORT MEDIA
Question Answer
• Thioglycolate brothfor strict anaerobes.
• Stuart transport mediuma non-nutrient soft agar gel containing a reducing agent to prevent oxidation, and charcoal to neutralise
• Certain bacterial inhibitorsfor gonococci,
• Buffered glycerol salinefor enteric bacilli.
• Krishna Rama (KR) mediumfor V. cholerae
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Enriched media
Enriched media contain the nutrients required to support the growth of a wide variety of organisms, including some of the more fastidious ones. They are commonly used to harvest as many different types of microbes as are present in the specimen.
Question Answer
• Blood agaris an enriched medium in which nutritionally rich whole blood supplements the basic nutrients.
• Chocolate agaris enriched with heat-treated blood (40-45 °C), which turns brown and gives the medium the color for which it is named.
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SELECTIVE MEDIA
GRAM POSITIVE BACTERIA
Question Answer
Mycobacterium tuberculosis-Löwenstein–Jensen medium ,-Middlebrook 7H9 Broth ,-Middlebrook 7H10 Agar ,-Middlebrook 7H11 Agar ,
Mycoplasma pneumoniae Eaton's agar
Corynebacterium diphtheria Hoyle's agar
EnterococcusBile esculin agar
LactobacillusMRS agar
LactococcusM17 agar
StaphylococcusMannitol salt agar
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