Growth Media Type Tryptone Soya Agar (TSA) plus Neutralisers

Other common names

The various manufacturers of dehydrated culture media do refer to TSA (Tryptone Soya Agar) by other names, as mentioned here. For products including neutralisers, some prepared media manufacturers use letters to denote the neutralisers included, such as LTTh. Cherwell have two typical presentations, media with Lecithin & Tween added or our Neutraliser 4 which also includes L-Histidine and Sodium Thiosulphate.

Primary Use

Tryptone Soya Agar (TSA) plus Neutralisers is a general-purpose medium for the growth of a wide variety of organisms, including both aerobes and anaerobes, the latter requiring anaerobic conditions. Neutralisers are included to inactivate disinfectant residues and therefore this medium is typically used in Contact plates.

Technical characteristics

The medium’s simple formulation consists of two types of peptone, Sodium chloride and agar, plus up to four disinfectant neutralisers.

To help offset the inclusion of the neutralisers, we typically supplement the agar content by adding a minimum of 1g of agar per litre.

Fresh and Irradiated TSA pH 7.3 ±0.2

Applications

The main application for Tryptone Soya Agar (TSA) plus Neutralisers is in environmental monitoring within pharmaceutical cleanrooms and sterile facilities. It is commonly gamma irradiated for increased sterility assurance. The medium is typically presented in Contact plates for surface monitoring to assess efficacy of cleaning regimes and to also assess gowning capabilities of operators.

Related reading:

• Are all contact plates the same when it comes to em?
• Why use neutralisers in your environmental monitoring plates?
• New cleanroom standard for microbiological contamination bs en 17141:2020

Appearance

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