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ISO 21149
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Quick understanding of the test
ISO 21149:2017 - Standard Method for Detecting Aerobic Mesophilic Bacteria in Cosmetics
- Staphylococcus aureus (ATCC 6538)
- Escherichia coli (ATCC 8739)
- Pseudomonas aeruginosa (ATCC 15442)
- Ensures consumer safety by identifying harmful bacteria.
- Helps avoid costly product recalls due to contamination.
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Abstract
ISO 21149:2017 is one widely accepted standard that provides guidelines for testing cosmetic products for microbial contamination. Ensuring the microbiological safety of cosmetic products is a crucial step in protecting consumers from potential health risks. The international standard describes methods to enumerate and identify the presence of pathogenic aerobic mesophilic bacteria in cosmetics. This standardization of the protocol makes it an essential tool for manufacturers aiming to meet high product quality as well as microbiological safety standards.
While this standard is applicable to a wide range of cosmetic products, alternative methods may be required for testing certain water-immiscible formulations. The presence of aerobic mesophilic bacteria is determined through either direct colony counting on agar plates or through an enrichment process that monitors the growth of bacteria.
Scope of products for testing with ISO 21149
ISO 21149 applies to a wide range of cosmetic products, including:
- Creams and lotions (oil-in-water or water-in-oil emulsions)
- Shampoos and conditioners
- Liquid soaps and shower gels
- Make-up and skincare products
- Raw materials used in cosmetic production
While this standard is applicable to a wide range of cosmetic products, alternative methods may be required for testing certain water-immiscible formulations.
Test organisms used in ISO 21149 testing
ISO 21149 test method for aerobic mesophilic bacteria detection
Plate method for ISO 21149 testing
- Pour plates or spread plates are prepared by using a specified culture medium.
- The plates are inoculated with a known quantity of initial suspension.
- The inoculated plates are incubated aerobically at 32.5ยฐC ยฑ 2.5ยฐC for 72 ยฑ 6 hours.
- After the incubation period, the number of colony-forming units (CFU) is counted and the number of aerobic mesophilic bacteria per ml per gram of the cosmetic product is calculated.
Membrane filtration in ISO 21149 test procedure
- A defined amount of sample is filtered through a membrane filter and washed in a filtration apparatus containing a small amount of suitable sterile diluent.
- The membrane filter is then transferred onto an agar plate and incubated at 32.5ยฐC ยฑ 2.5ยฐC for 72 ยฑ 6 hours.
- After incubation, the number of colony-forming units (CFU) is counted and the number of aerobic mesophilic bacteria per milliliter or per gram of the cosmetic product is calculated.
Detection of aerobic mesophilic bacteria by enrichment broth
- The sample mixture is then incubated at 32.5ยฐC ยฑ 2.5ยฐC for at least 20 hours.
- After incubation, an aliquot of the previously inoculated liquid medium is transferred to a non-selective solid agar medium.
- The plates are subjected to aerobic incubation at 32.5ยฐC ยฑ 2.5ยฐC for 48 to 72 hours.
- The plates are observed for any bacterial colonies and the results are expressed as the โpresence or absenceโ of aerobic mesophilic bacteria per sample of the cosmetic product.
Importance of ISO 21149 testing in cosmetic safety
ISO 21149 plays a vital role in ensuring microbial safety of cosmetic products, which are especially prone to contamination due to their nutrient-rich, often water-based formulations. By providing a standardized method to detect and quantify aerobic mesophilic bacteria, ISO 21149 helps manufacturers demonstrate compliance with global microbiological quality standards and verify the effectiveness of their preservation systems. This test minimizes the risk of product spoilage, costly recalls, and potential harm to consumers from pathogenic bacteria. It also supports product claims related to microbiological purity and shelf life, making it an essential tool for stability studies, routine quality control, and regulatory submissions.
At Microbe Investigations Switzerland (MIS), we provide ISO 21149 testing services that help cosmetic manufacturers ensure their products meet the highest standards of microbiological safety.
Alongside this test, MIS also offers related services including ISO 16212, USP 61, ISO 11930, ISO 18415, and custom microbial risk assessments tailored to your unique product formulations.
Our expert microbiologists work closely with your team to identify the most relevant tests for your product type, intended use, and market requirements โ ensuring full compliance with regulatory standards.
Contact us today to learn more about our services and how we can assist in safeguarding your cosmetic products.
Frequently Asked Questions
DR. Martinoz Scholtz
We perform this test using Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 8739), Pseudomonas aeruginosa (ATCC 15442). Additional strains can be added on customer request.
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