selective media for cryptococcus neoformans


Wed Jun 10 05:23:20 EST 1998


On Thu, 04 Jun 1998 23:46:35 -0700, Phil <jorge2 at earthlink.net> wrote:

>sandra wrote:
>> 
>> I am looking for the formule of a selective media for cryptococcus
>> neoformans of saprophytic origin, it is called Niger seed agar or Guizotia
>> abyssinica medium. I will also welcome any other alternative and selective
>> media for this organism. many thanks.
>> 
>> Sandra
>
>Sandra:
>
>Are you sure the seed extract agar is selective?  I think it may be
>differential.  You might just go with Mycosel or antibiotic BHI or PDA.


The Guizotia Abyssinica in the medium adds to the selectivity of the
medium by allowing C. Neoformans to form a brown pigment (melanin) by
which you can distinguish their colonies from others by their
chocolate-like colour.

You might want to read:
http://vega.crbm.cnrs-mop.fr/bioscience/1997/v2/e/william/e99-107.htm

Currently I am doing some research into C. Neoformans here at the
Medical Microbiology Dept. of the AMC-Hospital  (Academical Medical
Centre) in Amsterdam.
Here we use the following recipe:

Grind G.A. seed in blender
Cook for 30 min. (50 gr./liter)
Filter through gauze
Filter through tea towel
Add water to original volume.
Sterilize for 15 min. at 121 Celsius

Add:
Creatinine 1 gr./l. (Sigma Chemical Co. - St. Louis)
Glucose 1 gr./l.
KH2PO4 1 gr./l. (potassium-di-hydrogen-phosphate)
Methylviolet 2 mg./l. (Brocades - Amsterdam) to inhibit yeast growth
Bacto Agar 15 gr./l. (Difco Laboratories -  Detroit)

Sterilize 15 min. at 115 Celsius

Add:
20 E/ml. penicilline
0,1 mg./ml. gentamycine
0,01-0,1% biphenyl to inhibit mould growth. the lower concentration
gives more mould growth but the higher also gives some growth
inhibition of C. Neoformans.

Success!

I also have a question.

Here we used a chemoluminescent DNA-probe (Accu-Probe from Gen-Probe)
to identify C. Neoformans but unfortunately they have taken this out
of production.
Does anyone know of a similar probe-kit and where we could obtain
this?

If you do, lots of thanks.

Ben Muller




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