Potato Dextrose Agar, Granulated
Intended use
Recommended for the cultivation of yeasts and moulds from pharmaceutical products in accordance with the microbial limit
testing by harmonized methodology of USP/EP/BP/JP.
Composition**
Ingredients Gms / Litre
Infusion from potatoes 200.000
Dextrose (Glucose) 20.000
Agar 15.000
pH after sterilization ( at 25°C) 5.6±0.2
Directions
Suspend 39.0 grams in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by
autoclaving at 15 lbs pressure (121°C) for 15 minutes or as per validated cycle. Cool to 45-50°C. Mix well and pour into sterile
Petri plates or tubes as desired. In specific work, when pH 3.5 is required, acidify the medium with sterile 10% tartaric acid. The
amount of acid required for 100 ml of sterile, cooled medium is approximately 1 ml. Do not heat the medium after addition of
the acid.
Principle And Interpretation
Yeast and moulds constitute a large and divergent group of microorganisms consisting of several thousands species. Yeast and
moulds can cause various degrees of food decomposition. Invasion and growth may occur on virtually any type of food if
environmental conditions are not limiting. Some foodborne yeasts and moulds are undesirable because of potential hazards to
human and animal health (1).
Potato Dextrose Agar, prepared in accordance with the harmonized methodology of USP/EP/BP/JP (2,3,4,5) is recommended for
microbial limit tests in pharmaceutical testing. It is also used for stimulating sporulation, for maintaining stock cultures of certain
dermatophytes and for differentiation of typical varieties of dermatophytes on the basis of pigment production (6). Potato
infusion and dextrose (glucose) promote luxuriant fungal growth. Adjusting the pH of the medium by tartaric acid to 3.5 inhibits
the bacterial growth. Heating the medium after acidification should be avoided as it may hydrolyse the agar, which can render the
agar unable to solidify.
Type of specimen
Pharmaceutical samples
Specimen Collection and Handling
For pharmaceutical samples, follow appropriate techniques for sample collection, processing as per pharmaceutical guidelines
(2,3,4,5). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/face protection.
Follow good microbiological lab practices while handling specimens and culture. Standard guidelines should
be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations
1. For heavily contaminated samples, the media must be supplemented with inhibitory agents for inhibiting bacterial growth
with lower pH.
2. Some pathogenic fungi may produce infective spores which are easily dispersed in air, so examination should be carried out
in safety cabinet.
3. Further biochemical tests should be carried out for confirmation.
Performance and Evaluation
Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at
recommended temperature.
Quality Control
Appearance
Cream to yellow colored granular medium
Gelling
Firm, comparable with 1.5% Agar gel
Colour and Clarity of prepared medium
Yellow coloured clear to slightly opalescent gel forms in Petri plates
Reaction
pH of 3.9% w/v aqueous solution at 25°C (after sterilization).
pH
5.40-5.80
Growth Promotion Test
Growth Promotion was carried out in accordance with the harmonized method of USP/EP/BP/JP, and growth was observed
at 20-25°C for specified time. Recovery rate is considered as 100% for fungus growth on Sabouraud Dextrose Agar
Growth Promoting Properties
Growth of microorganism comparable to that previously obtained with previously tested and approved lot of
medium occurs at the specified temperature for not more than the shortest period of time specified inoculating = 100 cfu
Cultural Response
Cultural characteristics observed after incubation at 20-25 °C for 2-5 days. Recovery rate is considered as 100% for fungus
growth on Sabouraud Dextrose Agar.
Organism Inoculum
(CFU)
Growth Observed Lot
value (CFU)
Recovery Incubation
temperature
Incubation
period
Test strain preparation
# Aspergillus brasiliensis
ATCC 16404 (00053*)
50 -100 luxuriant 25 -100 =50 % 20 -25 °C 5 -7 Day
Additional Microbiological
Testing
Candida albicans
ATCC 10231 (00054*)
50 -100 luxuriant 35 -100 =70 % 20 -25 °C 2 -3 Day
Saccharomyces cerevisiae
ATCC 9763 (00058*)
50 -100 luxuriant 35 -100 =70 % 20 -25 °C 2 -5 Day
Rhodotorula mucilaginosa
DSM 70403
luxuriant 20 -25 °C 3 -5 Day
Geotrichum candidum
DSM 1240
good- luxuriant 25 -30 °C 3 -5 Day
Penicillium communae
ATCC 10248
fair -good 25 -30 °C 3 -5 Day
Trichophyton ajelloi
ATCC 28454
fair-good 25 -30 °C 3 -7 Day
Aspergillus fumigatus
ATCC 9197
50 -100 luxuriant 25 -100 =50 % 20 -25 °C 5 -7 Day
Please refer disclaimer Overleaf.
Quality Control
Appearance
Cream to yellow colored granular medium
Gelling
Firm, comparable with 1.5% Agar gel
Colour and Clarity of prepared medium
Yellow coloured clear to slightly opalescent gel forms in Petri plates
Reaction
pH of 3.9% w/v aqueous solution at 25°C (after sterilization).
pH
5.40-5.80
Growth Promotion Test
Growth Promotion was carried out in accordance with the harmonized method of USP/EP/BP/JP, and growth was observed
at 20-25°C for specified time. Recovery rate is considered as 100% for fungus growth on Sabouraud Dextrose Agar
Growth Promoting Properties
Growth of microorganism comparable to that previously obtained with previously tested and approved lot of
medium occurs at the specified temperature for not more than the shortest period of time specified inoculating = 100 cfu
Cultural Response
Cultural characteristics observed after incubation at 20-25 °C for 2-5 days. Recovery rate is considered as 100% for fungus
growth on Sabouraud Dextrose Agar.
Key :(#) - Formerly known as Aspergillus niger, (*) - corresponding WDCM numbers
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°C. Use before expiry date on
the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent
lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation.
Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly
after use. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this
product. Follow established laboratory procedures in disposing of infectious materials and material that comes
into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (7,8).
