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Login Join. Subscribe Free Magazine eNewsletter. Nelson Labs analyst performing a bioburden test. Image courtesy of Nelson Laboratories. A new version of the ISO document regarding bioburden testing was recently published. Though the document has a number of changes, this article will highlight the top five things manufacturers need to know.
Some products tested for bioburden can release substances that inhibit microorganism replication. The inhibitory substance is typically known to the manufacturer because it is intentionally included as part of the product i. Sometimes, however, an unknown inhibitory substance can be present that can be problematic because the manufacturer may believe there is no need to test for inhibitory substances.
For example, there might be residuals from cleaning or disinfecting processes on the product, or on components of the product that are provided by a supplier. When an inhibitory substance is present, the bioburden test results can look very low e. This is because inhibitory substances sometimes do not inactivate or kill the microorganisms; they merely inhibit them from replicating.
There is an analogous test used in qualifying a test of sterility. The intent behind that test is identical to the bioburden method suitability test. Both tests are in place to ensure there is nothing in the test system that will inhibit viable microorganisms from replicating.
Section 6. In the version of the standard, it was deemed important enough to add as one of the required items for selection of a test method. This same requirement was added to 7.
The additions are specifically written so that a manufacturer might choose to omit performing the bioburden method suitability test if they have a detailed understanding of all components and manufacturing processes relating to their product.
Based on this detailed understanding a manufacturer might know for a fact there are no inhibitory substances on, or in, their product and can provide a written rationale for not performing the test.
The effectiveness of the bioburden extraction process is determined in a recovery efficiency test. The importance of performing recovery efficiency testing has always been included, and is still represented in the version, but some details were added and some changes were made.
Section 7. This addition gives manufacturers more flexibility than what was allowed in the previous version. Section A. It previously indicated that if the recovery efficiency percentage was less than 50 percent, improvements or alternate techniques should be considered.
The 50 percent value was arbitrarily selected and not based on data. Since the use of an arbitrary value is not the best approach, the focus is now on consistency of the results obtained rather than whether a specific value has been achieved.
Annex C, section C. However, if bioburden recovery efficiency results fall below a target or desired value, another technique should be attempted e. It is important to note it is not required that companies establish a desired recovery efficiency for each product type.
Information on reviewing recovery efficiency data is provided in sections C. It suggests that a repetitive recovery efficiency is appropriate for products with a moderate to high bioburden e. Although it is not intended that these suggested values are exact cutoff points for either method, they do provide general guidance on when one might be more appropriate than the other. Bioburden testing is not meant to be an exact science, such as analytical chemistry, because the bioburden test involves two variables that are sometimes not quantifiable.
The second variable is that the test is meant to detect living organisms, and organisms vary in how they replicate, remain static, or die due to subtle differences in their environment.
Neither variable is consistent in different circumstances, and they are not easily explainable with the laws of physics. Thus, it is not possible to expect bioburden test results to be as accurate or precise as one would with an analytical chemistry test. That being said, however, it is important to take reasonable measures to make bioburden results as valid as possible.
Attempting to have a low LOD is one of those reasonable measures to consider. Section 8. The intent of Section 8. An example of this is the debate between a spread plate test method of 1. Although the spread plate is faster and easier, if zero colonies are detected on the plate, the results would be reported as less-than 50 CFU i.
Therefore, the LOD for this example is 4. Individual bioburden results are reported in whole numbers because the number is representative of a colony forming unit.
Averages or other mathematical calculations using bioburden data are typically reported to one decimal place. LOD can be improved by the following: a modification to the test method e.
Having this information, with the example and ideas on improving LODs, is a benefit to the industry. When these concepts are employed, bioburden data can become more useful to manufacturers in detecting changes before they become a problem, in trending manufacturing practices, and in establishing alert and action levels. Since guidance on this topic was excluded from the standard, some manufacturers performed routine bioburden testing for all inner packaging.
Some in the industry believed that routine testing of all interior packaging was required e. In an effort to correct this practice, guidance was added to section A. Typically, it is sufficient to perform a bioburden determination on a product after its removal from its packaging system and to omit the packaging system from the determination. Depending upon the sterile label claim, internal packaging components, such as a tray or product insert, may need to be tested based upon factors such as: What is intended to be sterile, When the package is an integral part of the product, or For specific evaluation.
First is that packaging usually does not have direct contact with the patient, which makes the potential risk to the patient lower for the packaging than for product itself.
Some might say that contaminated packaging can transfer microorganisms to product, which then can transfer to the patient. Note the first sentence in A. This means any transfer of microorganisms that could occur on product used on patients will also occur on product used for testing; thus, any microbiological contribution of packaging is accounted for.
Second, bioburden testing of packaging unnecessarily complicates the bioburden test. Inclusion of packaging usually entails additional cutting and manipulation to ensure that it will fit into the container used for testing.
Some might say that swabbing could be used to remedy that issue. However issues associated with swabbing such as poor recovery efficiency from the surface to the swab and then poor recovery from the swab to the test system indicate this might not be the best method.
Some of the packaging will float on top of the extraction fluid, making a full extraction of the surface area difficult. Also, when packaging is tested with product, it usually fills the container which further increases the difficulty of extraction.
One answer is to test packaging separately from the product. This is almost always best practice, but it does add cost to the testing. When there is added cost but little or no true benefit, continued use of the practice should be questioned.
Manufacturers need to understand the potential contribution to product bioburden that packaging can make. Therefore, performing some bioburden testing of packaging to obtain data is a good practice. Manufacturers are usually recommended to test packaging initially, but in a separate container to determine the separate packaging bioburden counts from product bioburden counts.
Once the data are gathered and it is determined that the results are acceptable, there is no need to test packaging on a routine basis. At that point, proper implementation of change control and good microbiological controls in inspection and storage processes is sufficient. In an attempt to provide clearer guidance for both manufacturers and testing laboratories, a table of responsibilities has been included in Annex D. This table indicates where collaborative efforts between the manufacturer and the testing lab would ensure the best testing method is utilized for the product in question.
Examples of where it is the responsibility of both the manufacturer and laboratory include selection of bioburden method, test method suitability for validation of the bioburden method, and removal technique. Whereas, specification of acceptable bioburden levels and trending are the responsibility of the manufacturer and items such as preparation and sterilization of materials and microbial characterization are laboratory responsibilities.
In most cases, assistance and information from both sides is the best approach. Correction to the Standard While items are the top five changes in the new revision deemed important enough to highlight, there is one additional item that needs to be mentioned. The formula placed into the standard is incorrect and is in the process of being corrected.
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Medical Device Bioburden and Sterility Testing
For Medical Devices the Bioburden is commonly determined after production and in the final packaging, but before sterilization. The level of Bioburden is an important parameter for the sterilisation process of the devices. Bioburden is an overall name for the total contaminaton of the product with an aerobic bacteria, Yeasts and Moulds. Bioburden and microbiological validation When a product is validated according to ISO method 1, there is a direct relation between the level of Bioburden and the required minimum dose of Gamma Radiation in order to claim a Sterility Assurance Level of 10E Next to VDmax25 which substantiates 25 kGy as a routine sterilisation dose also other doses can be validated. Depending on the product Bioburden this range can be from 15 kGy to 35 kGy. Bioburden and monitoring After a succesful validation it is required to monitor the Bioburden after production of the next batches.
Five Aspects of the ISO 11737-1:2018 Updates You Need to Know
What medical device manufacturers need to know about the recent changes to the ISO bioburden standard. Read Full Story. Wendy Mach has over 24 years of medical device manufacturing and laboratory experience. She worked in the medical manufacturing environment in Minnesota for seven years, performing ethylene oxide EO and gamma radiation sterilization validations. While at the manufacturing site, she also insourced the microbiology tests for sterility assurance and related equipment validation. Wendy also spent
It is important when conducting these tests to ensure that the testing method does neither introduce microorganisms into the test sample nor kill microorganisms in the test sample. It was one of first and is still one of only a few contract labs in the country currently ISO Biological certified. Gibraltar Laboratories follows the bioburden testing procedure described in ISO Bioburden and microbial detection are also required for process validation, cleaning validation, aseptic operation, qualification of water systems, and personnel monitoring. In accordance with ISO regulations, classical bioburden testing takes 7 days for yeast and molds results. Facebook Twitter LinkedIn. Search for:.
Bioburden Testing ISO 11737