When it comes to microbial quality assurance (MQA), it’s a proactive, comprehensive system that is in place within the manufacturing, food, cosmetic, and pharmaceutical industries to ensure safe, sterile products that are free of harmful microorganisms. This process involves adhering to the Hazard Analysis and Critical Control Points (HACCP) standards that oversee proactive measures designed to identify and mitigate risks before they become an issue. It also involves strict Standard Operating Procedures (SOPs), validation of testing methods, and adherence to the Current Good Manufacturing Practices (cGMP), among other factors.
Microbial testing is a key part of the process and a vital aspect of quality control and regulatory compliance. It is used to detect bacteria, contaminants, and fungi in products or on equipment. Bioburden testing and sterility testing are two components of this process. We will look deeper into each practice below, but as a preview, bioburden testing looks for the presence of viable microorganisms (and counts their quantity) prior to sterilization and sterility testing verifies the absence of these living microorganisms.
Understanding Bioburden Testing Definition and Purpose
The basic definition of bioburden testing is the measuring of the total number of live microorganisms (microbial load) that exist on a product, device, or component prior to sterilization. Its purpose in pharmaceuticals is to ensure patient safety and to meet regulatory compliance with governing organizations like the FDA or ISO 11737 standards, along with other mandates, as well as these additional objectives:
- Validation of Sterilization: Bioburden testing is often used in order to properly calculate the sterilization parameters that are then applied using radiation to effectively eliminate microbes.
- Manufacturing Control: This type of testing also verifies the safety of production processes, the raw materials being used, and the environment itself.
- Identifies Process Deviations: Bioburden serves the role of regular monitoring tool and can detect contamination early in the production process, before the final sterilization.
- Quality Control: It also ensures that non-sterilized products meet the proper or safe level of microbial contamination and ensures that all sterile products maintain a low starting microbial population.
The process of bioburden testing is often performed by aseptically extracting microorganisms either through membrane filtration or fluid flushing, which is then followed up by incubation and counting colony forming units (CFU). This is the number of viable living microorganisms present, like bacteria, fungi, or spores. Overall, bioburden testing is a critical aspect of monitoring within the manufacturing process as a way to ensure quality and patient safety.
Understanding Sterility Testing: Definition and Purpose
The definition of sterility testing is a critical, regulatory procedure that verifies whether products that are intended to be sterile are in fact free from viable microorganisms. It is a final quality control check that ensures regulatory compliance and protects patient safety. The following are even more objectives fulfilled by sterility testing:
- Verification of Sterilization: One of the most important purposes of sterility testing is to serve as confirmation that a specific manufacturing process has been performed successfully and that there are no viable microorganisms remaining on a product or device.
- Ensure Regulatory Compliance: Sterility testing is also used to meet regulatory compliance like the strict requirements set forth by USP <71> and meet other compliance standards that oversee pharmaceutical products.
- Monitor Manufacturing Environments: This type of testing also acts as a control mechanism that checks for contamination that could indicate failures in other areas like aseptic techniques or sterilization procedures.
Sterility testing is most often performed using membrane filtration. This is used for oils, soluble powders, and liquids. The sample is passed through a filter to capture microbes, which is followed by rinsing to remove antimicrobial properties, then the membrane is cultured in media. Another option for sterility testing, which is used when products cannot be filtered, like ointments, bulky devices, or creams, is direct inoculation involving incubation of 14 days. This involves taking a small sample and directly adding it to the cultural media.
Key Differences Between Bioburden Testing and Sterility Testing
The key differences between bioburden testing and sterility testing can be summed up as they differ in both purpose and timing, while they are complementary procedures that are both critical for maintaining regulatory compliance and keeping patients safe in the pharmaceutical and medical device realms. The following will outline some key differences between these two procedures:
- Primary Objective: Bioburden’s primary objective is to quantify the viable microbes on a device or in a product before sterilization. Sterility testing’s main purpose is to confirm the absence of viable microorganisms on a product after sterilization has been performed.
- Timing: Bioburden testing is performed before sterilization at the beginning of the process, while sterility testing is completed after sterilization, at the end of the process in many cases.
- Output: The main output for bioburden testing is quantitative, meaning an average number or CFU. The key output for sterility testing is qualitative, meaning the result is either pass or fail, meaning there is growth or no growth of microorganisms.
- Incubation Time: Another key difference between these processes involves the incubation period. For bioburden testing, this is typically 3-5 days. For sterility testing, incubation time is generally 14 days.
- Standardization: Bioburden testing is overseen by ISO 11737-1 and USP <61> as well as updated USP <119> and <1119.1> guidelines, while sterility testing must meet ISO 11737-2 and USP <71> guidelines.
- Methodology: The testing process itself also differs, with bioburden testing mainly being an extraction followed by filtration and thenpour plates, while sterility testing is membrane filtration or direct inoculation into a culture media.
- Purpose: Last, but certainly not least, the overall purpose of these two processes is different, with bioburden being a process control or a validation of a sterilization dose, while sterility testing’s purpose is to validate the safety of a final product.
Regulatory Standards and Compliance Requirements
The global approach to pharmaceutical bioburden and sterility testing has been largely aligned among major pharmacopeias, like JP, EP, and USP, heavily influenced by ICH guidelines and has been enforced by regulatory agencies like the EMA and FDA, which have rigorous and strict validation and method requirements to ensure product efficacy and patient safety. The following is the most up-to-date regulatory framework.
Bioburden Testing Standards & Compliance
USP <119> and <1119.1>
These new chapters, USP <119> and <1119.1>, provide a more comprehensive framework surrounding bioburden monitoring. This is supplemental guidance for in-process controls, especially as they relate to biologics.
USP <61> EP 2.6.12
The Microbiological Examination of Non-Sterile Products: Microbial Enumeration Tests and also includes Total Aerobic Microbial Count TAMC and Total Yeast and Mold Count TYMC.
USP <62> EP 2.6.13
This standard looks at specific organisms like aureus and E. coli to determine the absence or presence.
ISO 11737-1
This standard specifically governs medical devices and defines the methodology and assessment of microorganisms on medical devices.
Incubation Time
TAMC incubation time is typically 3-5 days, and the method suitability requires demonstrating adequate microbial recovery, commonly around 70%.
Sterility Testing Standards & Compliance
USP <71> EP 2.6.1
This standard involves the harmonization of methods for sterility testing requiring a 14-day incubation period.
Methods
The membrane filtration is the preferred method for sterility testing for filterable products.
EU GMP Annex 1
The EU GMP Annex 1 emphasizes a comprehensive Contamination Control Strategy CCA throughout the product’s life cycle, which is mandatory for compliance in sterile product manufacturing.
Overall, regulatory trends are moving more toward a risk-based approach that is compliance focused with robust documentation and method suitability or validation requirements that are strictly audited.
Best Practices for Implementing Bioburden and Sterility Testing
The best way to implement bioburden and sterility testing into quality control processes is to embrace a risk-based approach. This includes regular monitoring, incorporating in-process bioburden testing with stringent and validated sterility testing to validate the final products. Best practices include using only validated testing methods, enforcing strict contamination controls like isolators, trending results for alert and action limits, and then employing rapid microbial methods for faster actionable data results.
Risk-based sampling strategy involves developing, justifying, and documenting sampling plans, frequencies, and limits based on specific risks at each manufacturing step. In addition, validating all methods confirms accuracy, detecting even small amounts of contaminants. Make sure that alert limits and action plans are robust and that bioburden data trends to review and act on limits before problems grow large. Overall, maintaining high levels of environmental monitoring and control in both sterile and non-sterile production areas and performing routine audits of cleanrooms to help prevent cross-contamination is important.
Contact Us at BA Sciences
Both bioburden and sterility testing are key components of producing safe and effective pharmaceutical products. Of course, the difference between sterile and non-sterile environments and these testing methods themselves are notable. However, in many ways, they are used in conjunction with each other to establish safety, ensure regulatory compliance, and promote drug efficacy. At BA Sciences, we partner with you in this process and welcome you to learn more about our medical device testing services.
We have provided a variety of high-quality analytical testing services to life sciences companies worldwide since 1987. We are also ISO accredited to perform microbial count testing on raw materials, pharmaceutical products, and water. Contact us today to learn more and learn how your company can receive your own dedicated project manager to oversee your project and help you establish and meet key goals.