BioBurden and EndoToxin Questions



Hi Guys,

I'm new to this site and relatively inexperienced in the Quality Sector.

Basically I've been thrown in at the deep end and handed a Sterility Project for our components and assemblies and I'm looking for some further information.

I've been referring to the various ISO and USP standards:
ISO 10993-1, Biological evaluation of medical devices ? Part 1
ISO 11137: Sterilization of health care products - Radiation Parts 1 and 2
ISO 11737: Sterilization of medical devices - Microbiological methods Parts 1 and 2
ISO 13485:2012, Medical devices - Quality management systems
ISO 14971:2012, Medical Devices ? Application of risk management to medical devices
ANSI/AAMI ST72: 2011, Bacterial endotoxins - Test methodologies, routine monitoring, and alternatives to batch testing

US Pharmacopeia: Chapter <61> Microbial limit tests
US Pharmacopeia: Chapter <71> Sterility tests
US Pharmacopeia: Chapter <85> Bacterial endotoxins test

I don't have access to the following (Anybody know where I could find it online?):
ISO 15843:2000, Sterilization of health care products - Radiation sterilization

We are in essence a middle link in the supply chain, we receive components in, assemble them in a cleanroom, and provide to our customers.
I have asked our suppliers for any Bioburden information they can supply and so far those requests have come up with nothing.

We have quite a large number of components to be sent for Bioburden testing and I'm trying to reduce this number and that's where I'm hoping you guys can come in.

  • Do I need to have all components tested for BioBurden Levels and then classify them accordingly into family products?
  • Can I classify them according to manufacturing location, process, raw materials? For example, if I have 5 identical components with the only difference being increasing size or internal diameter, would this not automatically qualify the largest as the master product? Or do I need to substantiate that by having all components tested first and using the component with the highest levels?
I would appreciate any guidance in this matter.


Thanks Ajit,

The final product will be Gamma irradiated single use tubing and component assemblies for Pharma customers.

We receive the components individually from various suppliers and assemble them in a Class VII cleanroom prior to Irradiation.

Ideally we would be able to supply the assemblies for aseptic manufacturing, but the main goal is to be able to provide a sterile product and validate our Product Family classifications in order to reduce size/cost of testing.

Ajit Basrur

As per the regulations,

The bioburden should be monitored before sterilization. There should be working limits on contamination immediately before sterilization, which
are related to the effi ciency of the method to be used. Bioburden assay should be performed on each batch for both aseptically filled products and terminally sterilized products. Where overkill sterilization parameters are set for terminally sterilized products, bioburden might be monitored only at suitable scheduled intervals. For parametric release systems, bioburden assay should be performed on each batch and considered as an in-process test. Where appropriate, the level of endotoxins should be monitored.


(broken link removed)

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Fully vaccinated are you?
In case the links change...


  • Manufacture of sterile medicinal products GMP Annex 1.pdf
    169 KB · Views: 380
  • GMP Sterile Pharmaceutical Products TRS961 Annex6.pdf
    167.2 KB · Views: 325


Thanks for the links. The interpretations are handy to have.

Just to follow up with Bioburden testing.

We have too many components in too many different sizes to send as part of the same Set or Assembly for bioburden testing.

What I am trying to do classify each component into a Product Family and then compile a master assembly that is representative of each Product Family.

Say for example, I have, a tube with a different connection piece on either end. Internal Diameter of 2 inches.

And say I have the another assembly, only difference, Internal diameter of 1/2 inch.

Now say I have a 3rd assembly, only difference, Internal Diameter of 1 inch.

So I have 3 pieces for the 2 inch assembly, 3 pieces for the 1 inch assembly and 3 pieces for the 1/2 inch assembly.

What I want to be able to do is provide rationale for just including the 3 pieces of the 2 inch assembly (Greater surface area) and use them as representative of the other 2.

Is that acceptable or do I have to have the bioburden results of all 3 assemblies before I can say the 2 Inch assembly is the worst case scenario and any subsequent testing only needs to performed on the 2 inch.

Does that make sense or have I lost you?


You can usually group components into bioburden families if they come from the same supplier and the same process and processing area, are made from the same raw material from the same upstream supplier, and are packaged and handled similarly at their and your ends to get the components from the supplier to your production line.

I say "usually" because if testing shows that the bioburden varies between production batches, then probably bioburden accumulation is driven by some aspect of the total process that is batch variable and uncontrolled. A family approach cannot be justified if any aspect of the above outlined control system is inconsistent and uncontrolled.

Note that either you should have testing to establish the pattern of seasonal variation in bioburden levels and do all sterilization qualifications using data and samples from the greatest bioburden period, or if you must qualify now and you do not have such data, you must periodically test (perhaps monthly) for bioburden levels to verify that production batches do not have bioburden levels that exceed the levels for which you have qualified, and maintain that testing until you have identified the greatest-bioburden seasonal time and you have re-qualified at those levels if necessary.

Such testing is needed because at northern locations i.e. Minnesota, bioburden tends to be greatest in dry winter months because of static attraction; and in southern locations i.e. Costa Rica, DR or PR, bioburden tends to be greatest during humid summer months because of microbial-growth-supportive conditions.
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