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Clostridium

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Clostridium. - Microscopic appearance of different species. - Differentiation between species according to biochemical reactions. Clostridium perfringens. Clostridium perfringens. - PowerPoint PPT Presentation
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Clostridium - Microscopic appearance of different species - Differentiation between species according to biochemical reactions.
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Page 1: Clostridium

Clostridium

- Microscopic appearance of different species.

- Differentiation between species according

to

biochemical reactions.

Page 2: Clostridium

Clostridium perfringens

Page 3: Clostridium

Clostridium perfringens

Page 4: Clostridium

On Blood Agar C. perfringens produces large beta-haemolytic colonies are produced. Some strains produce a double zone of haemolysis.

Page 5: Clostridium

1- Prepare a plate of lactose egg yolk milk agar

2- Turn the plate over, and using a wax pencil, draw a line across the centre of the plate

3- Using a sterile swab, cover one half of the medium withC. perfringens antitoxin. Allow to dry

Page 6: Clostridium

5- Inoculate also a non-toxin producing control organismthat will grow anaerobically.

6- Incubate the plate anaerobically at 35–37 ºC overnight.

7- Look for an opacity around the inoculum in the half of the plate containing no antitoxin and no opacity in the half containing the antitoxin.

4- Inoculate the test organism at right angles to the centreline (inoculum passes from the antitoxin-freehalf of the plate to the antitoxin-covered half.

Page 7: Clostridium

A heavy inoculum of the test organism is incubated for up to4 hours in a tube containing litmus milk. Reduction of thelitmus milk is indicated by a change in colour of the mediumfrom mauve to white or pale yellow

Litmus Milk Reduction Test

Page 8: Clostridium

Nitrate Reduction Test

C.perfringens can reduce nitrate to nitrite which detected by addition of sulfanilic acid which react with nitrite to form diazonium salt which react with added alpha-naphthylamine to form red colour.

Page 9: Clostridium

Lecithinase C activity: Seen as an opacity in the medium dueto the breakdown of lecithin in the egg yolk.

Lipase hydrolysis: Seen as (fatty) layer coveringcolonies and sometimes extending into the medium.

Lactose fermentation: There is a reddening in the medium.The colonies become red on exposure to air.

Proteinase activity (proteolysis): Shown by an area of clearingaround the colonies due to the breakdown of casein in themilk by the enzyme proteinase.

Page 10: Clostridium

On lactose egg yolk medium, C. perfringens:

● Produces lecithinase C (alpha toxin)

● Ferments lactose

Page 11: Clostridium

C.perfringens

produce proteolytic enzyme (gelatinase) that liquefy gelatin.

Gelatin Hydrolysis

Page 12: Clostridium

On Robertson’s cooked meat medium C. perfringens is saccharolyticand slightly proteolytic.

Page 13: Clostridium

Clostridium botulinum

Page 14: Clostridium

Clostridium botulinum

Page 15: Clostridium

Clostridium botulinum

Page 16: Clostridium

On Blood Agar C. botulinum produces large semi-transparent colonies with a wavy outline. Most strains are beta-haemolytic

Page 17: Clostridium

On Robertson’s cooked

meat medium C. botulinum

is proteolytic.

Page 18: Clostridium

Clostridium tetani

Page 19: Clostridium

Clostridium tetani

Page 20: Clostridium
Page 21: Clostridium

On Blood Agar C. tetani producesa fine film of growth. Use a hand lens to examine the plate.

On fresh blood agarC. tetani is haemolytic(alpha first followed by beta haemolysis).

Page 22: Clostridium

When C.tetani is cultured in a medium which contains tryptophan. Indole production is detected by Kovac’s reagent

which contains 4 (p)-dimethylaminobenzaldehyde which reacts with the indole to produce a red coloured compound.

Indole Production

Page 23: Clostridium

Clostridium difficle

Page 24: Clostridium
Page 25: Clostridium

On Blood Agar C. difficile produceslarge non-haemolytic colonies.

Page 26: Clostridium

C. difficile can grow in bile esculin agar and turns the indicator ferric ammonium citrate to a dark brown color results from combination of esculetin end product of esculin hydrolysis with ferric ions to form a phenolic iron complex.

Esculin

Hydrolysis


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