Cetrimide Broth

Media
Standard Methods Agar
Products
Standard Methods Agar
Used for obtaining microbiological
plate counts from milk and dairy
products, foods, water and other
materials of sanitary importance.
The formulation of this medium
follows the demands of the Standard
Methods for the Examination of
Water and Wastewater, the American
Public Health Association, the
American Water Works Association
and the Water Pollution Control
Federation in 1992 and the Standard
Methods for the Examination of Dairy
Products of the American Public
Health Association (1985).
Description:
All bacteria develop on Standard
Methods and produce a range of
different colored and sized colonies.
Interpretation:
It is not possible using Standard
Methods Agar to presumptively identify
any bacteria. Identification can only be
undertaken using traditional microbiology
techniques following initial colony
development.
Organisms
Characteristics Coloring
E. coli ATCC 25922 Growth Yellow to
cream
S. aureus ATCC 25923 Growth Yellow to
cream
Quality Control and recommended
incubation conditions:
Positive control:
Escherichia coli ATCC 25922,
incubated 48 hours at 35º C.
Negative control:
Not undertaken.
Sterility:
7 days plated sterility test.
Historical background:
Standard Methods Agar is a
modification of Bowers and
Hucker Tryptone Glucose Skim
Milk Agar. It was shown by Yale
to be more effective in plate
count procedures on milk and
dairy products.
The American Public Health
Association in their ”Standard
Methods for the Examination of
Dairy Products“ recommends
the use of Standard Methods
Agar for performance of the
”Standard Plate Count“ on
dairy products.
Standard Methods Agar is the
same formulation as Plate
Count Agar recommended by
the APHA for use in the
”Standard Plate Count“ on
water.
Standard Methods Agar with membrane filter and
incubated with a pure culture of Escherichia coli
ATCC 25922.
Formulation:
Per liter of water adjusted
to pH 7.0 ± 0.2
Pancreatic Digest of Casein
Yeast extract
Dextrose
Agar
5.0 g
2.5 g
1.0 g
15.0 g
Same agar as above but incubated with a mix
culture of Escherichia coli ATCC 25922 and
Staphylococcus aureus ATCC 25923. Both form
yellow to creamy colonies.
Order information Standard Methods Medium
Product Description Qty/Pkg Order No
Bottled agar 100 ml 1 10 496 706
Petri dishes with sterile pads 47 mm 100 10 498 544
Petri dishes with sterile pads 50 mm 50 10 445 905
* available on request
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