Microbiological Examination of Nonsterile Products
USP <61> covers microbiological examination of nonsterile products for total aerobic microbial count (TAMC) and total yeast and mold count (TYMC). USP <62> covers tests for specified microorganisms. Both are compendial standards required for product release.
What this does not cover
stated in the document's own scope- Apply to nonsterile products; sterility testing of products required to be sterile is the subject of USP <71>.
- Provide the enumeration and specified-organism test methods, not the acceptance limits — those are in the companion informational chapter <1111>.
- Test the product for microbiological quality, not the manufacturing environment, which is monitored under USP <1116> and the applicable GMP.
Always verify against the current published text before relying on it for a submission or inspection.
Overview
USP General Chapters <61> and <62> are the compendial microbiological examination of nonsterile products. Chapter <61>, Microbial Enumeration Tests, quantifies the total aerobic microbial count (TAMC) and the total combined yeasts and moulds count (TYMC) present in a product. Chapter <62>, Tests for Specified Microorganisms, checks for the absence — or acceptable control — of named organisms such as Escherichia coli, Salmonella, Staphylococcus aureus, and Pseudomonas aeruginosa, chosen by dosage form and route of administration. Together they define the microbiological quality of a nonsterile product for release.
Scope & applicability
All manufacturers of nonsterile pharmaceutical products (oral solids, creams, ointments, APIs) required to meet USP compendial standards for microbial limits.
Legal basis & how it acquires force
Chapters <61> and <62> are USP–NF general chapters numbered below 1000, which makes them enforceable when a monograph or an applicable requirement invokes them — and in the US, USP–NF standards are recognised under the Federal Food, Drug, and Cosmetic Act. The acceptance criteria themselves are not in <61> or <62> but in the companion informational chapter <1111>, which sets microbiological acceptance limits by product category. So the test method is the mandatory part and <1111> supplies the limits it is judged against.
Document structure
| Part | Covers |
|---|---|
| <61> Microbial enumeration | Quantitative determination of total aerobic microbial count (TAMC) and total yeasts and moulds count (TYMC) |
| <61> Method suitability | Demonstrating the product does not inhibit recovery of the test organisms (growth promotion / neutralisation) |
| <62> Specified microorganisms | Tests for the absence or control of named organisms (E. coli, Salmonella, S. aureus, P. aeruginosa, and others) |
| <62> Test-organism selection | Which specified organisms apply by dosage form and route of administration |
| Companion limits (<1111>) | The microbiological acceptance criteria the enumeration and specified-organism results are compared against |
Key requirements
- Method suitability testing demonstrating growth promotion in the presence of the product
- Standardised methodology for TAMC, TYMC, and specified organism tests
- Validated analytical procedures with documented suitability
- Retention of method suitability records linked to each test method
Revision notes
Current revision 2021. Terminology updated from "method validation" to "method suitability" to align with harmonised guidelines.
Where this control fails
live FDA enforcementLive FDA recalls SPEQ maps to this standard’s topics — a SPEQ interpretation, not an FDA classification.
International alignment
Chapters <61> and <62> are harmonised across the three major pharmacopoeias — USP, the European Pharmacopoeia (2.6.12 and 2.6.13), and the Japanese Pharmacopoeia — through the Pharmacopoeial Discussion Group, so the enumeration and specified-organism methods are broadly interchangeable. They are supported by the laboratory best-practice chapter <1117> and complement the sterility test <71>, which applies to products that must be sterile rather than nonsterile.
USP <61>/<62>: frequently asked questions
Quick answers to common questions about USP <61>/<62>.
What is the difference between USP <61> and <62>?
Chapter <61> is a quantitative enumeration test — it counts total aerobic microbes (TAMC) and total yeasts and moulds (TYMC). Chapter <62> is a qualitative test for the absence or control of specified organisms such as E. coli and Salmonella. Both apply to nonsterile products.
Where are the acceptance limits for <61> and <62>?
Not in the test chapters themselves. The microbiological acceptance criteria by product category live in the companion informational chapter USP <1111>, against which the <61>/<62> results are judged.
Are <61> and <62> harmonised internationally?
Yes. They are harmonised with the European and Japanese pharmacopoeias through the Pharmacopoeial Discussion Group, so the methods correspond to Ph. Eur. 2.6.12 and 2.6.13.
This standard in practice
Recall domain is a SPEQ mapping of this standard’s topics, not an FDA classification.