Sterility test

The purpose of a sterility test verify the complete absence of viable microorganisms (bacteria, yeasts, molds) in a finished product or raw material. Performed under aseptic conditions, it is an essential step in the microbiological quality control of sterile products or products susceptible to contamination.

This analysis ensures the microbiological safety of products intended for human or animal use and guarantees their regulatory compliance before they are placed on the market. Sterility testing is particularly applicable to pharmaceuticals, medical devices, non-preserved cosmetics, and formulations for ocular and injectable use .

Analytical methods and reference standards

The sterility test is performed according to recognized international standards:

• European Pharmacopoeia (chapter 2.6.1)
• ISO 11737-2: 2019 — Sterilization of medical devices — Microbiological methods of 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 a 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.).

Matrices involved

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.
• Non-preserved cosmetics : serums, lotions, masks, eye care or products for sensitive skin.
• Food or nutraceutical products with a 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 the microbiological conformity of non-preserved 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 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…).
• Accelerated stability test to evaluate the microbiological durability of products.
• Dosage of preservatives to control the antimicrobial efficacy of cosmetic formulations.

YesWeLab's expertise

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

Thanks to the YesWeLab digital platform , you can order, track and view your analyses online , while benefiting from tailored technical support.