Other common names

The various manufacturers of dehydrated culture media do refer to TSA by other names, these include Casein Soya Bean Digest Agar, Soybean Casein Digest Agar, CASO Agar and Tryptic Soy Agar.


Primary Use

Tryptone Soya Agar is a general-purpose medium for the growth of a wide variety of organisms, including both aerobes and anaerobes, the latter requiring anaerobic conditions.

 

 

Technical characteristics


The medium’s simple formulation consists of two types of peptone, sodium chloride and agar.

Typical formulation: g/ltr
Pancreatic digest of casein 15.0
Enzymatic digest of soya bean 5.0
Sodium chloride 5.0
Agar 15.0

Fresh and Irradiated TSA pH 7.3 ±0.2

Applications


The main application for TSA is in environmental monitoring within pharmaceutical cleanrooms and sterile facilities. It is commonly gamma-irradiated for increased sterility assurance and can be supplemented with neutralisers for disinfectants or enzymes.

TSA is also typically used as a reference medium when testing other selective media.

Related reading:


Appearance


The prepared media is pale straw to straw in colour with a slightly opaque appearance.

Organisms & morphology


Tryptone Soya Agar will support the growth of a wide range of aerobic and anaerobic bacteria if incubated under the right conditions.

A typical set of control organisms and the phenotypic identification associated with these are:

Related reading:

 

Morphology

Gram

Biochemical test

Organism

Edge

Shape

Colour

Gram

Shape

Catalase

Oxidase

Staphylococcus aureus

Smooth

Regular

Yellow/ Cream

Positive

Cocci

Positive

Negative

Staphylococcus epidermidis

Smooth

Regular

Yellow/ Cream

Positive

Cocci

Positive

Negative

Escherichia coli

Smooth

Regular

Cream

Negative

Rods

Positive

Negative

Bacillus subtilis 

Irregular

Irregular

Cream

Positive

Rods

Positive

Variable

Pseudomonas aeruginosa

Smooth

Regular

Cream

Negative

Rods

Positive

Positive

 

 

Morphology

Fungal

Edge

Shape

Colour

Candida albicans

Smooth

Regular

Cream

Aspergillus brasiliensis

Irregular

Irregular

White to black

Typical incubation parameters

As TSA is a general-purpose medium, it can be incubated at differing temperatures depending on the target organisms. In environmental monitoring applications, it is common for plates to be incubated at 30-35°C for bacterial colonies and 20-25°C for mould and fungi.

 

EP Chapter Ref 2.6.12 Microbial examination of non-sterile products: Microbial enumeration tests

Recommended Culture Media

Property

Micro-organisms

Incubation Time & Temp

Casein Soyabean Digest Agar

Growth promotion

Bacillus subtilis
Pseudomonas aeruginosa
Staphylococcus aureus

30-35ºC for < 3 days

Growth promotion

Candida albicans
Aspergillus brasiliensis

30-35ºC for < 5 days


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Regulatory references


TSA is a Harmonised Pharmacopoeia medium and as such is mentioned in the BP/EP/JP, as well as the US Pharmacopoeia.

Related reading:

 

The Pharmaceutical and Cleanroom Industry's Pocket Guide to Prepared Media

Got questions about selecting the best media for your business, storage best practice or generating a bespoke formulation? Our guide will help.


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