Whether you are testing raw materials, in-process samples, or finished goods, the right compendial method depends on your product type, formulation, and regulatory market. Here’s a working overview.
1. USP <61>: Microbial Enumeration
USP <61> is the foundational compendial method for quantitative microbial enumeration, measuring Total Aerobic Microbial Count (TAMC), and Total Yeast and Mold Count (TYMC) in non-sterile pharmaceuticals, OTC products, cosmetics, and raw materials. TAMC and TYMC results are compared against USP-defined acceptance criteria (USP <1111>) for the applicable product category. For manufacturers producing non-sterile products across any of these categories, USP <61> testing is the starting point for a defensible microbial safety profile. This method is harmonized with the European Pharmacopoeia EP 2.6.12.
2. USP <62>: Detection of Specified Objectionable Microorganisms (Presence/Absence Test)
USP <62> is the compendial method for detection of specified objectionable microorganisms, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella, Candida albicans, Bile-tolerant Gram-Negative Bacteria and Clostridia. Unlike the enumeration approach of USP <61>, the USP <62> chapter has presence/absence tests for specified microorganisms of concern. For products with defined regulatory limits on specified, or for manufacturers investigating contamination events, USP <62> testing provides enrichment and selective/differential methods for specified microorganisms that may be present in very low numbers in a product that total-count methods do not. Confirmatory testing of detected microorganisms can be performed through Microbial Identification by Genotypic and Proteotypic Methods. This method is harmonized with the European Pharmacopoeia EP 2.6.13.
3. USP <60>: Burkholderia cepacia complex screening for Water-Based Non-Sterile Products
Burkholderia cepacia complex (BCC) comprises a group of Gram-negative, rod-shaped bacteria that are notorious for their opportunistic nature and specific concern in water-based non-sterile pharmaceuticals, OTC products, cosmetics, and raw materials e.g. water. Standard microbial enumeration methods are insufficient for BCC detection, which requires enrichment and selective/differential screening media to detect these organisms. USP <60> addresses this with a method specifically designed for BCC identification and screening. For formulators working with aqueous systems, including OTC drug products, topical formulations, and certain cosmetic categories, BCC screening is a material component of a complete microbiological safety assessment.
4. ISO 21149 and ISO 16212 (Enumeration Methods) and ISO 18415 Detection of Objectionable Organisms (Presence/Absence Methods): Cosmetic Microbiology under International Standards.
For manufacturers selling into international markets or operating under ISO-aligned quality systems, cosmetic microbiology testing under ISO 21149 (Aerobic Mesophilic Bacteria Enumeration and Detection) and ISO 16212 (Yeast and Mold Enumeration and Detection) and ISO 18415 (Presence/Absence testing for Detection of Objectionable Organisms) provides the regulatory-grade data required by non-USP markets. CPT℠ Labs conducts both ISO methods, supporting manufacturers who need test data recognized across EU, Asian, and other international regulatory frameworks, not just the U.S. market.
5. USP <2021> and <2022>: Microbial Testing for Dietary Supplements.
Dietary supplements present a distinct microbial testing context: TAMC and TYMC enumeration under USP <2021> and presence/absence testing for specified microorganisms under USP <2022>. Both apply manufacturer- or product-specific criteria in addition to compendial limits. Botanicals, nutritional ingredients, and blended supplement matrices introduce formulation-specific recovery challenges that require confirmation of method suitability before routine testing. CPT℠ Labs conducts both methods, with the required method suitability work to generate valid results for dietary supplement matrices.
6. Test Method Suitability: the step that determines whether your test data is actually valid.
For each product type, selecting the right microbial enumeration (pour plate, membrane filtration or Most Probable Number (MPN)) or specified organism detection method, depends on the product type, formulation, and microbial load. More importantly, method suitability testing must be completed before routine testing begins because product ingredients and preservative systems can interfere with microbial recovery and yield falsely low or negative counts. CPT℠ Labs conducts method suitability testing as a defined step before routine microbial programs, ensuring that the methods applied to a given product are validated to recover target organisms at accurate levels.
Trust CPT℠ for Your Cosmetic & OTC Drug Product Testing
CPT℠ Labs provides USP, EP, ISO, and compendial microbial content testing for raw materials, in-process samples, and finished products across pharmaceutical, OTC, cosmetic, and dietary supplement categories. Get started with your quote today!