Sterility test

The sterility test aims to verify the total absence of viable microorganisms (bacteria, yeasts, molds) in a finished product or raw material. Carried out under aseptic conditions, it constitutes an essential step in the microbiological quality control of sterile products or those sensitive to contamination.

This analysis helps to guarantee the microbiological safety of products intended for human or animal use, and to ensure their regulatory compliance before being placed on the market. The sterility test applies in particular to pharmaceutical products, medical devices, non-preserved cosmetics or formulations for ocular and injectable use .

Analytical methods and reference standards

The sterility test is carried out according to recognized international standards:

• European Pharmacopoeia (chapter 2.6.1)
• ISO 11737-2:2019 — Sterilization of medical devices — Microbiological methods for validation and control.
• USP <71> (United States Pharmacopeia)

Two main methods can be used depending on the nature of the product:

Membrane filtration method

• The sample is filtered through a sterile membrane (0.45 µm or 0.22 µm).
• The filter is then placed in specific liquid culture media:
• Tryptic Soy Broth (TSB) for the detection of aerobic bacteria.
• Fluid Thioglycollate Medium (FTM) for anaerobic microorganisms.
• The media are incubated at controlled temperature for 14 days.

Direct seeding method

• The sample is directly inoculated into the culture media.
• This method is suitable for non-filterable products (creams, gels, powders, polymers).

Any microbial growth detected is examined to identify the contamination and determine its nature (bacterial, fungal, etc.).

Affected matrices

The sterility test applies to a wide variety of matrices:

• Sterile pharmaceutical products : injectable solutions, eye drops, implants, capsules.
• Medical devices : catheters, dressings, surgical instruments.
• Unpreserved cosmetics : serums, lotions, masks, eye care or for sensitive skin.
• Food or nutraceutical products with high microbiological risk.
• Materials and packaging intended to come into contact with sterile products.

Industrial and regulatory applications

This test is a major requirement for sectors subject to strict safety and asepsis standards :

• Pharmaceuticals and medical devices : sterilization validation, production control, batch release.
• Cosmetics : verification of microbiological conformity of unpreserved or sensitive products.
• Agri-food and nutraceuticals : control of products intended for direct consumption or therapeutic use.
• Materials and polymers industry : validation of the microbiological cleanliness of primary packaging.

The results of the sterility test help ensure regulatory compliance and demonstrate control of microbiological risk throughout the manufacturing process.

Related analyses

For a complete assessment of microbiological quality, YesWeLab recommends combining the sterility test with:

• Search for specific pathogenic germs (Pseudomonas, Staphylococcus, Candida, etc.).
• Accelerated stability test to assess the microbiological durability of products.
• Dosage of preservatives to control the antimicrobial efficacy of cosmetic formulations.

YesWeLab expertise

YesWeLab relies on a network of ISO 17025 and COFRAC accredited laboratories , specialized in microbiological analyses and sterilization validation .

Thanks to the YesWeLab digital platform , you can order, track and consult your analyses online , while benefiting from tailor-made technical support.