Trypticasein Soy Agar (TSA) with Neutralizings. Double Wrapped. Irradiated

Description

Classical medium for the microbiological examination of non-sterile products according to Pharmacopeial Harmonised Methods.

The addition of the neutralizing agents TLHTh (Tween 80 - Lecithin - Histidine - Sodium Thiosulphate) may inactivate a variety of disinfectants.

• The combination of lecithin, polysorbate 80 and histidine neutralizes aldehydes and phenolic compounds.
• The combination of lecithin and polysorbate 80 neutralizes the quaternary ammonium compounds.
• The polysorbate 80 neutralizes hexachlorophene and mercurial derivatives.
• Sodium thiosulphate neutralizes halogen compounds.
• Lecithin neutralizes chlorhexidine.
• Histidine neutralizes formaldehyde.

Technique

Contact plates are used in the microbiological control of disinfection and cleaning of surfaces. They act simultaneously as a sampler and incubation culture medium without the need for any other intermediate steps.

The plates come in a form appropriate for this function and can be used with different culture media depending on the type of microbe that needs to be controlled. On average the plates provide a contact surface of approximately 25 cm².

To use, remove the cover and gently press the culture medium on the surface to be controlled, ensuring contact between the two surfaces. The contact plate is removed and covered with the lid to prevent air contamination. It is advisable that the lid is secured with adhesive tape and the bottom labelled with the sampling data (place, date and time).

If the sample surfaces are rough, the contact plates will not make good contact, even when the pressure is increased. In these cases it is advisable to delineate a sample surface area of 25 cm² and rub this area vigorously with a wet sterile swab and then rub the swab over the contact plate.

If verifying the effectiveness of a cleaning or disinfection process, contact plates should be used within two hours after the end of the process, ensuring that the sample surface is dry. It is advisable to always include positive controls, sampling the area before disinfection or dirty areas beside the disinfected area.

The technician will determine the frequency of sampling and disinfection according to performance criteria. Apply the agar directly onto the surface to be monitored ensuring that the pressure is distributed over the whole plate for 10 seconds. Clean the surface where the sample was collected in order to remove any traces of agar.

The inoculated plates are incubated at 30-35 °C for 24-72 h (bacteria) and 3-5 days for fungi (yeasts and molds). Examined daily.

Note: Contact plates are used for monitoring the microbiological contamination of surface and air inside cleanrooms, isolators, RABS, food industries and hospitals. The double/triple irradiated wrapping ensures that the package itself doesn't contaminate the environment as the first wrapper is removed just before entering the clean area.

Physical/chemical control

Microbiological control

Growth Promotion Test according to harmonized pharmacopoeial monographs and test methods and ISO 11133:2014.

Inoculate: practical range 100 ± 20 CFU; min. 50 CFU (productivity) / 10⁴-10⁶ (selectivity).

Aerobiosis. Incubation at 30-35 °C. Read after 18-24 h to 72 h for bacteria and 3-5 days for fungi.

Sterility control

Incubation 48 h at 30-35 °C and 48 h at 20-25 °C: NO GROWTH.

• ATLAS, R.M. & L.C. PARKS (1993) Handbook of Microbiological Media. CRC Press, Inc. London.
• COLIPA (1997) Guidelines on Microbial Quality Management (MQM). Brussels.
• DOWNES, F.P. & K. ITO (2001) Compendium of Methods for the Microbiological Examination of Food, 4th ed, ASM, Washington D.C.
• EUROPEAN PHARMACOPOEIA 8.0 (2014) 8th ed. § 2.6.13. Microbiological examination of non-sterile products: Test for specified microorganisms. Harmonised Method. EDQM. Council of Europe. Strasbourg.
• FDA (Food and Drug Administration) (1998) Bacteriological Analytical Manual. 8th ed. Rev. A. AOAC International. Gaithersburg. MD.
• HORWITZ, W. (2000) Official Methods of Analysis of AOAC INTERNATIONAL, 17th ed. Gaithersburg, MD. USA.
• ISO 9308-1 Standard (2000) Water Quality. Detection and enumeration of E. coli and coliform bacteria. Membrane filtration method.
• ISO 11133:2014/Amd 1:2018. Microbiology of food, animal feed and water. Preparation, production, storage and performance testing of culture media.
• ISO 16212 Standard (2017) Cosmetics - Microbiology - Enumeration of yeast and mould.
• ISO 21149 Standard (2017) Cosmetics - Microbiology - Enumeration and detection of aerobic mesophilic bacteria.
• ISO 21150 Standard (2015) Cosmetics - Microbiology - Detection of Escherichia coli.
• ISO 22717 Standard (2015) Cosmetics - Microbiology - Detection of Pseudomonas aeruginosa.
• ISO 22718 Standard (2015) Cosmetics - Microbiology - Detection of Staphylococcus aureus.
• ISO/TS 22964 (2006) Milk and milk products - Detection of Enterobacter sakazakii.
• PASCUAL ANDERSON, Mª R. (1992) Microbiología Alimentaria. Díaz de Santos S.A., Madrid.
• USP 33 - NF 28 (2011) <62> Microbiological examination of non-sterile products: Test for specified microorganisms. Harmonised Method. USP Corp. Inc. Rockville. MD. USA.