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 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.

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

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

USP <62> describes growth and recovery of specific organisms. USP requires that prior to routine specified microorganisms testing, a 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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10 Grams/mls/patches for USP 61 test while 30 to 40 grams/mls/patches for USP 61 Suitability Test

10 Grams/mls/patches for USP 62 test while 30 to 40 grams/mls/patches for USP 62 Suitability Test

3 to 7 days for USP61 test and 10 to 14 days for USP 61 Suitability Test

5 to 7 days for USP 62 test while 10 to 14 days for USP 62 Suitability Test

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