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8/13/2019 Media Rasha

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Culture media

Transport Media


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TYPES OF CULTURE MEDI


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Def.: Media containing inhibitorysubstances ( dyes or bile salts orantibiotics) that inhibit the growth of

certain organisms and allow thegrowth of others.

Lowenstein Jensen.

Blood tellurite agar.

Thayer Martin media.

Selective media


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Jensen medium (L.J):-) Lowenstein1(Color:It is opaque green in colour.

Composition:It is composed of beaten egg, mineralsalts and malachite green.

Sterilization:It is solidified by heating it in theinspissator at 75C for 1 hour.

Uses:Cultivation of Tubercle bacilli from contaminatedpathological sample e.g. sputum, because themalachite green inhibits the growth of bacteria

other than T.B.


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Lowenstein Jensen medium

showing dry heaped up yellow

colonies of M. tuberculosis.

L.J. uninoculated


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) Blood tellurite agar:2(

Composition: Blood agar + K tellurite 0.03%.

Uses:

1. Isolation of C. diphtheria from throat swabs, since itinhibit most of the normal flora of the upper respiratorytract.

2. Used for the typing of C. diphtheria into Gravis, Mitisand Intermedius due to the varying black to grey colour

they produce as a result of reduction of tellurite totellurium.


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Mitis Intermedius Gravis

Corynebacterium diphtheria colonies on bloodtellurite agar


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)THAYER MARTIN MEDIA:3(

Composition:

-Modified chocolate agar, whichcontain many special growth factors

required by N. gonorrhoeae.

-It contain also, 3 antibiotics;Vancomycin, Colistin and Nystatin which

inhibit the growth of other commonsaprophytes.

Uses:

Selective media for culture of N. gonorrhea.


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Colonies of Vibrio cholera on TCBS


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Indicator media

Def. : Media containing an indicator thatchanges its color as a result of the bacterialmetabolic activity.

MacConkeys medium.

CLED.

TSI

XLD.


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MEDIUM CCONKEYS.

Composition:1. Peptone(for nutrition).

2. Agar(solidifying agent).

(sodium taurocholate)Bile salts:Inhibitor.3(indicator thatNeutral red:Indicator.4

changes pink in the presence of acid which isproduced as a result of lactose fermentation)

(test sugar).Lactose:Test sugar.5

Sterilization:Autoclave.


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Uses:Cultivation of enteric bacteria and

differentiate between two major groups of entericbacteria:1- Lactose fermenters (L.F) group: give

rose pink colonies e.g the coliform group (E. coli,klebsiella, citrobacter).2-Non-lactose fermenters (Non L.F)

group: give pale yellow colonies and include theSalmonella, Shigella, proteus and pseudomonas.


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LFNLF

)(


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)(XLDDEOXYCHOLATE)XYLOSE LYSINE2(

Composition:

Xylose Lysine Test sugar: Sucrose Indicator: Phenol red

Inhibitor: Bile saltsUses:Selective isolation of salmonella and

shigella.NLF >>> Red colonies.

LF >>> Pale colonies

Salmonella : red colonies with black center due toH2S production.


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Salmonella typhi on XLD


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)TRIPLE SUGAR IRON (TSI)3(

Composition: 1%Glucose. 1%Lactose.

1% Sucrose. Indicator: Phenol red.

Uses:

To differentiate salmonella and shigella fromother enteric Gram negative bacilli in stoolcultures.


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There are three possible sugar reactions on this medium:Principle(1) Bacteria which ferment only glucose will give small

amount of acid which will change the color of the butt into yellowcolor while the slant will remain red. i.e Red/Yellow OR

alkaline/acid reactione.g salmonella and shigella.(2) Bacteria which ferment lactose and/or sucrose will

produce copious amounts of acids enough to change the color of both

the slant and the butt into yellow. i.e.yellow/yellowOR acid/acid

reaction e.g E.coli and Klebsiella pneumoniae.

(3) Bacteria with nocarbohydrate fermentation will produceno acid end products and both the slant and the butt will remain

red. Final reaction is Red/RedOR alkaline/alkalinee.g.

Pseudomonas.(4)Bacteria fermenting glucose only with H2S production willgive red slant and black butt (color of H2S masks the yellow color of

the butt) i.e.Red/ Black e.g salmonella and some species of

proteus.

TSI di


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Pseudomonas

TSI medium

Acid/Acid

Klebsiella

Alkaline/Acid

Salmonella

Alkaline/Acid+H2S

Salmonella


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(3) CYSTEIN LYSINE ELECTROLYTE DEFICIENTMEDIUM (CLED)

Color:Greenish or bluish color. Sterilization: Autoclave.Uses:

1. Quantitative culture of urine samples(supports the growth of all organismscausing UTI).

2. Differentiates between:LFYellow colonies.

NLF

Pale colonies.


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INDICATOR MEDIA

CLED


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INDICATOR MEDIA


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SUGAR MEDIA


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Uses:To test the biochemical reaction of bacteria.

Composition: Peptone water.

1% of the sugar tested.

1% Andradsindicator which is colourless when alkaline andturns red when acid.

A small inverted tube (Durhams tube) is immersed in the tubecontaining the medium. Gas produced as a result of acidfermentation collects in the closed upper end of the Durhamstube

SUGAR MEDIA


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SUGAR MEDIA

T di


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Uses and advantages:Maintain the viability of the pathogen and avoids overgrowth

of contaminants till the sample is transported from thepatient to the lab.

Examples:1. Stuarts transport medium: For gonococci on swabs.

2. Amies medium: Charcoal impregnated , supports the

growth of many pathogens.

3. Glycerol salinetransport medium: Maintains typhoidbacilli in stool and prevents intestinal organisms fromovergrowing typhoid bacilli.

Transport media


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TRANSPORT MEDIA

Amies transport medium

Stuarts transport medium


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