CONTACT PLATE: TRYPTIC SOY AGAR W/ LECITHIN & TWEEN 80

Technical Data #1558a / 2005.08.18

Contact TSA Agar w/ Lecithin and Tween 80 is a general purpose culture medium used for detection and enumeration of microorganisms on the surface of sanitary containers, equipment and surfaces. Casein and soy peptones are the source of nutrients. Sodium chloride maintains osmotic equilibrium. Lecithin and Tween 80 are neutralizers used to inactivate residual disinfectants. The culture media is applied directly to surface being tested; collection of samples from identical areas "before and after" permit to evaluate cleaning procedures in environmental sanitation.

FORMULA
in grams per liter purified filtered water

Casein Peptone	15,0
Soy Peptone	5,0
Sodium Chloride	5,0
Lecithin	0,7
Tween 80	5,0
Agar	20,0

pH 7.3 +/- 0,2 à 25º C

This approximate formula may be adjusted and/or enriched to obtain best results.

PRECAUTIONS
This medium is for laboratory use only.

STORAGE
Store prepared media at 2-8º C protected from direct light and dehydrated powder, in a dry place, in tightly-sealed containers at 2-25º C.

SIGN OF DETERIORATION
Media should not be used if the expiry date has passed. Prepared media should not be used if there are signs of contamination or deterioration (shrinking, cracking, evaporation or discoloration). Do not use dehydrated media if it is caked.

DIRECTIONS
Suspend 51 g of dehydrated media in 1000 ml of purified filtered water. Heat with frequent agitation and boil for one minute. Sterilize at 121º C for 15 minutes. Cool to 45-50º C. Mix gently and dispense into sterile Contact Petri dishes with a positive meniscus.

PROCEDURE
Prior to inoculate, the prepared media should be brought to room temperature.

1. Apply the plate's agar surface directly to the surface being tested with a gentle pressure. Roll the plate if a curved surface is tested.
2. Incubate plates at 35º C, for 24-48 hours.
3. Count the colonies.

QUALITY CONTROL
Results after 24 hrs at 35ºC

Organisms	ATCC	Growth
Staphylococcus aureus	6538	+
Staphylococcus aureus	25923	+
Escherichia coli	25922	+
Candida albicans	10231	+
Candida albicans	60193	+
Bacillus subtilis	6633	+
Bacillus subtilis	23059	+
Aspergillus niger	16404	+

LIMITATIONS OF METHOD
Contact plate method is used for establishing, revising or monitoring cleaning programs and for detecting and counting microbial populations. This medium is only a part of the identification. Other tests may be required.

REFERENCES

1. Dowell, V.R.Jr., G.l. Lombard, F.S. Thompson, A.Y. Armfield 1977 Media for isolation, characterization and identification of obligately anaerobic bacteria. CDC Laboratory Manual. Center for Disease Control, Atlanta
2. Lennette, E.H., Ballows, A., Hausler, W.J.Jr., and Shadomy, H.J. Manual of Clinical Microbiology. 4th ed. 1985 Washington D.C.: American Society for Microbiology.
3. Livingston, S.J., S.D. Kominos, R.B. Yee 1978 New medium for selection and presumptive identification of the Bacteroides fragilis group. J. Clin. Microbiol. 7:488-453.
4. Sutter, V.L., D.M. Citron, M.A.C. Edelstein, S.M. Finegold Wadsworth Anaerobic Bacteriology Manual 4th ed C.V. Mosby St. Louis
5. Favero, Gabis and Vesley. 1984. In Speck (ed.), Compendium of methods for the microbiological examination of foods, 2nd ed. American Public Health Association, Washington, D.C.
6. Sveum, Moberg, Rude and Frank. 1992. In Vanderzant and Splittstoesser (ed.), Compendium of methods for the examination of foods, 3rd ed. American Public Health Association, Washington, D.C.

CATALOGUE NUMBERS

Dehydrated media	500 g	QB-39-5211
Prepared media
Contact Plates, 65x15 mm	10/pkg	1558

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