USP 61 and USP 62 tests are carried out for Microbiological Examination of Non-Sterile Products.

USP <61> Microbiological Examination of Non-Sterile Products: Microbial Enumeration Tests

USP 61 determines the number of microorganisms present - i.e. "Enumeration of microorganisms"

The USP 61 test is performed in routine to determine the "total aerobic microbial count" (TAMC) and "total yeasts and molds counts" (TYMC). Enumeration of microorganisms can be carried out by membrane filtration, pour plating, or the spread plate method.

USP <62> Microbiological Examination of Non-Sterile Products: Tests for Specified Microorganisms

USP 62 is performed in routine to test the presence of specified microorganisms:
Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, bile-tolerant Gram-negative bacteria, Clostridia species, Salmonella species and/or Candida albicans.

In the case of USP 62 testing, the sample is first enriched by inoculating in Soybean Casien Digest Broth (SCDA), or other appropriate neutralizing media, and then streaked onto selective agars for determination of the presence of specified / objectionable microorganisms.

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The new USP <61> and USP <62> tests provide harmonization to existing European Pharmacopeia methods for testing non-sterile pharmaceuticals.

The new harmonized USP <61> describes the microbial enumeration tests. USP requires that prior to routine enumeration testing, a one-time suitability of counting method / Method Validation must be performed.

The new harmonized USP <62> describes growth and recovery of specific organisms. USP requires that prior to routine specified microorganisms testing, a one-time suitability of test method / Method Validation must be performed.

USP 61 Validation/ Suitability
<100 CFU of Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Candida albicans, and Aspergillus brasillensus are inoculated to demonstrate the validation of the plate count method and media used.

USP 62 Validation / Suitability testing
Demonstrates the recovery of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, bile-tolerant Gram-negative bacteria, Clostridia species, Salmonella species and Candida albicans.

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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