Sterility Testing
Sterility Testing is a critical quality control procedure to ensure the absence of viable microorganisms in buffers, reagents, and media. Even minimal microbial growth can significantly alter the pH, ionic strength, and stability of a buffer, affecting its behavior and compromising experimental reproducibility or further manufacturing processes. The most widely used methodology for this testing is USP <71>[1].
History of Sterility Testing
Sterility testing originated in the late 19th century, initially focused on ensuring that injectable and implantable products were free from harmful microorganisms. Over time, testing methodologies became more sophisticated and standardized, driven by pharmacopeial standards such as the United States Pharmacopeia (USP).
Though historically tied to pharmaceutical applications, sterility testing has become increasingly important for research-use and manufacturing reagents, as microbial contamination can compromise not only experimental integrity but also downstream processes.
Importance of Sterility Testing
While sterility testing in pharmaceuticals protects patient safety, in buffers and reagents, it is essential for:
- Maintaining chemical and functional integrity – Microbial growth can change buffer pH, precipitate components, or degrade sensitive reagents.
- Ensuring reproducibility – Contaminated buffers can cause inconsistent experimental outcomes.
Protecting downstream processes – In bioprocessing or manufacturing workflows, contamination in a single reagent can compromise entire batches.
Sterility Testing at Boston BioProducts
At Boston BioProducts, our Quality Control team provides reliable sterility testing in adherence to USP <71>, designed specifically for buffers, reagents, and media. After manufacturing, samples of the final reagent are first evaluated for testing suitability, then subjected to sterility testing. Suitability testing evaluates the product for any antimicrobial properties that would affect growth, or other undesirable properties that would lead to a false negative result during testing.
Our methodology uses positive and negative controls with multiple replicates and includes samples in different media types, including the product itself—for enhanced reliability. Testing involves 14 days of incubation, after which sterility is confirmed by the absence of microbial growth or turbidity, validated by successful controls, full data logging, and appropriate replicates.
How is USP <71> assessed?
- Samples are collected aseptically and transferred into aerobic and anaerobic growth media.
- The inoculated media is incubated under controlled conditions for 14 days.
- No turbidity or growth indicates sterility, any growth triggers further investigation.
Considerations and Limitations of USP |
|
|---|---|
| Aseptic Techniques | Strict aseptic handling is required during sampling and testing to avoid false contamination. |
| Time Efficiency | Sterility testing is time-sensitive, and the duration of incubation must be carefully controlled to yield accurate results. |
| Result Interpretation | False positives or negatives may occur due to reagent composition; results must be carefully validated. |
| Testing Suitability | Highly viscous or antimicrobial buffers may require pre-validation for sterility testing. |
| Equipment Maintenance | Testing equipment and filtration systems must themselves be sterile to ensure reliable results. |
Boston BioProducts provides a comprehensive set of QC tests for custom reagents. Learn more about custom reagent development services