USP 61 Microbiological Examination of Nonsterile Products

• Soybean-Casein Digest Agar (TAMC)
• Sabouraud Dextrose Agar (TYMC)

USP 61 Microbial Enumeration Test Methods

Membrane Filtration

Plate Count Methods

• Pour-Plate Method
• Surface-Spread Method

Most-Probable-Number-Method

• Tubes are used for microbial growth

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Interpretation / Analysis of Results for USP <61> Microbial Enumeration Tests

TAMC - Total Aerobic Microbial Count

• equal to number of cfu found using Soybean-Casein Digest Agar
• if colonies of fungi are apparent, they are counted and included in TAMC

• equal to number of cfu found using Sabouraud Dextrose Agar
• if colonies of bacteria are apparent, they are counted and included in TYMC

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More information about this test can be viewed at the following other locations:
-U.S. Pharmacopeia (Chapter <61> PDF)
-The Harmonization of the Microbial Limits Test - Enumeration by Scott Sutton, Ph.D.
-USP Updates <61> and <62> for Microbial Testing of Non-Steriles

• The United States Pharmacopeia (USP) has significantly changed the USP XXXI <61> Microbial Limits Test, updating it and dividing it into two parts