Trypticase™ Soy Agar with Lecithin and Polysorbate 80

Intended Use
These media are recommended for the detection and enumeration of microorganisms present on surfaces of sanitary importance.
Prepared plates are provided for environmental monitoring.
Sterile Pack and Isolator Pack RODAC™ prepared plates are particularly useful for monitoring surfaces in clean rooms, Isolator Systems and other environmentally-controlled areas and are also recommended for use in air sampling equipment such as the Surface Air System. Finger Dab™ Sterile Pack and Isolator Pack plates are intended for sampling gloved hands.

Summary and Explanation
These media may be employed to establish and monitor cleaning techniques and schedules. Collection of “samples” from identical areas before and after treatment with disinfectant yields data useful in evaluating cleaning procedures in environmental sanitation. Tryptic (Trypticase) Soy Agar with Lecithin and Polysorbate 80 is recommended for the Aerobic Plate Count (Microbial Limit Test) for water-miscible cosmetic products containing preservatives.

RODAC (Replicate Organism Detection and Counting) and contact plates are used in a wide variety of surface sampling programs and may be employed to establish and monitor cleaning techniques and schedules. The presence and number of microorganisms on a flat impervious surface is determined by the appearance of colonies on the surface of the medium following application to the test surface and incubation. The RODAC plate has a marked grid to facilitate counting organisms. The RODAC SL (Secure Lid) has three lugs on the base, providing a tight fit between lid and base to reduce accidental contamination.

The 100 × 15 mm and the 150 × 15 mm style plates can be used for active and passive air sampling. These plates are also designed for personnel monitoring of finger tips (Finger Dab).

Principles of the Procedure
Casein and soy peptones are a source of nutrients required for the replication of microorganisms. Sodium chloride maintains osmotic equilibrium. Lecithin and polysorbate 80, two commonly used neutralizers, are reported to inactivate residual disinfectants when the sample is being collected. Lecithin is incorporated to neutralize quaternary ammonium compounds and polysorbate 80 is used to neutralize substituted phenolic disinfectants. Agar is the solidifying agent.
Trypticase Soy Agar with Penicillinase and Trypticase Soy Agar with Lecithin, Polysorbate 80 and Penicillinase contain 50 mL/L of penicillinase, which inactivates antibiotics such as penicillins and cephalosporins.
With the Sterile Pack and Isolator Pack plates, the entire double-wrapped (Sterile Pack) or triple-wrapped (Isolator Pack) product is subjected to a sterilizing dose of gamma radiation, so that the contents inside the outer package(s) are sterile. This allows the inner package to be aseptically removed without introducing contaminants. Since the agar medium has been sterilized after packaging, the presence of microbial growth after sampling and incubation can be relied upon to represent true recovery and not pre-existing medium contaminants. A third rolled sterile bag is included as a transport device. Isolator Pack plates have been validated to protect the medium from vaporized hydrogen peroxide when used in an Isolator System.

Formulae
Difco™ Tryptic Soy Agar with Lecithin and Polysorbate 80
(Microbial Content Test Agar)
Approximate Formula* Per Liter
Pancreatic Digest of Casein : 15.0 g
Soy Peptone : 5.0 g
Sodium Chloride : 5.0 g
Lecithin : 0.7 g
Polysorbate 80 : 5.0 g
Agar : 15.0 g

User Quality Control
NOTE: Differences in the Identity Specifications and Cultural Response testing for media offered as both Difco™ and BBL™ brands may reflect differences in the development and testing of media for industrial and clinical applications, per the referenced publications.

Identity Specifications
Difco™ Tryptic Soy Agar with Lecithin and Polysorbate 80 (Microbial Content Test Agar)
Dehydrated Appearance: Beige, free-flowing, homogeneous, may appear moist.
Solution: 4.57% solution, soluble in purified water upon boiling with frequent gentle swirling. When hot, solution is medium amber, slightly opalescent with a resuspendable precipitate.
Prepared Appearance: Light to medium amber, slightly opalescent, may have a precipitate.
Reaction of 4.57%
Solution at 25°C: pH 7.3 ± 0.2