Microbial Limits

Testing of any cosmetic, pharmaceutical or personal care product should include a survey for contamination often referred to as testing for Microbial Content, which uses assays designed to measure the growth of bacteria, yeasts and molds in order to flag products for the presence of contaminants. This assay involves enumeration of aerobic, mesophilic bacteria, yeast and molds in product samples that might include both raw materials to finished goods. The tests are designed primarily to determine whether a substance or preparation complies with an established specification for microbiological quality such as USP Monographs, and/or manufacturer’s acceptance criteria.

This testing consists of two parts. The quantitative phase, Microbial Enumeration, gives the total number of aerobic organisms as well as a total yeast and mold counts for a sample. The qualitative phase is known as the Test for Specified Microorganisms. This test is designed to determine the presence or absence of specific objectionable organisms in a product.

For most cosmetic and toiletry products, regulations require that the total aerobic count should be <100 cfu/g, and that yeast and mold counts should be <10 cfu/g. The workflow of the testing of a personal care sample for the presence of microbial contamination is very simple and requires a fraction of the time and labor needed to perform the same tests using the USP methodology. Each product can also be assayed specifically for the detection of E coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella species.

What are the advantages of the BioLumix system?

Time Saving: The results are available much faster using BioLumix test vials, for example, the results of the Yeast and Mold vials occurred in less than 48 hours, while the Aspergillus plate count takes approximately five days.  Products tested with bacteria using the automated BioLumix assay generally yielded results within 12-20 hours, instead of 48 hours for the plate count methodology.

Labor Saving: The setup of the assay can be done much faster using the BioLumix system as opposed to traditional plating methods, saving significant hands-on labor due to its automation and simplicity of use.   The assay is paperless, increasing efficiency and saving on disposables, time and space, and best of all the system is unaffected by product interference.  The System is extremely easy to operate, with its straightforward and streamlined testing design and it offers accurate results leading to reduced material-holding time for faster product release.

High Correlation with USP: The BioLumix System showed a high correlation between the instrument results and the USP methodology (Brideau & Eden 2013).   The system is fully automated with automated data archiving, data maintenance in archived databases, and automated report generation.  Regulators encourage rapid microbiology methods for improved process control and product release.  The BioLumix system is validated as being at least equivalent to the compendial method.  Under general notices of the USP, it  states that “Automated procedures employing the same basic chemistry as those assay and test procedures given in the monograph are recognized as being equivalent in their suitability for determining compliance.”


Reference:  Brideau, R and R Eden (2013) Cosmetic, OTC and Nutraceutical Products: Advantages of rapid automated microbiological testing.  NutraCos (3)-1 January/April pg 13.



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