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Help for Chocolate agar plate

Tony Stott tony.stott at med.monash.edu.au
Wed Nov 29 00:55:25 EST 2000

Simon Lee wrote:
> I want to solve the problem about the chocolate agar palte.
> The our method of preparation is belows.
> 1. 2L ditilled water + 144 gm GC agar powder
> 2. dissolve fully with heating till boiling
> 3. autoclave
> 4. cooling till 45 C degree
> 5. add 5% defibrinated sheep blood
> 6. heating to 65 C degree
> 7. cooling till 45 C degree
> 8. add IsoVitale X 1 vial
> 9. pouring into plate.
> The problem is two
> One ; there are many sand like particle on the surface and inner side
> of agar plate. - I have heard that the problem is stirring during
> phase 5,6 ? Is it right ?
> Two ; the color of chocolate agar palte is too dark
> Please help me ASAP.
> Simon Lee

Back in the "olden days" when I actually used to work with nasty disease
causing germs ;-) we used one of the methods described in Cowan and
Steel's Manual for the Identification of Medical Bacteria (2nd Edition)
1974. This was to pour your plates as normal blood agar plates then
place then (media side down) in a 65 degreeC incubator for 1 to 1.5
hours untill they turned brown. We used horse blood rather than sheep
blood and didn't use IsoVitaleX but never had any trouble growing stuff
like meningiditis and gono etc even when those stains were sent to us by
the quality contol people from the Royal College of Pathologists.
Tony Stott
IT Support
Department of Microbiology
Monash University, Clayton, Victoria, Australia

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