End-User or Third-Party Population Verification

Introduction

Users of biological indicators (BIs) need to have an appropriate level of knowledge of the product and its intended use prior to purchase.  Once achieved, users also need to have confidence in the quality of the product received prior to placing it into use. There are two general methods for gaining confidence in product quality, 1) performing a quality audit(s) of the manufacturer to verify compliance to relevant standards/regulations, and 2) performing quality testing on each incoming BI lot. There are several important BI qualities that can be evaluated by second/third parties including, BI spore count (population), BI resistance to the process (D-value or Survival/Kill), and identity/purity of the test organism.

This edition of Spore News will cover the various aspects of population verification. BIs contain live organisms that are shipped long distances, and as such, verification of the population (as an incoming inspection activity) is recommended. Verification of population is not a complex task; however, it is important to perform these assays per the manufacturer’s instructions to achieve meaningful results. Relevant standards and other resources are provided below.

Standards & References

ISO 11138-7:2019 Sterilization of health care products – Biological indicators – Part 7: Guidance for the selection, use and interpretation of results

6.1.4 When the user has established a high level of confidence in the supplier (see 6.1.3), the testing performed by the user can be minimal. At a minimum, the user should have a mechanism to ensure that a shipment of biological indicators contains all agreed-upon documentation, such as appropriate label information, packet inserts, storage and handling instructions, etc. There should be a mechanism to ensure that the BI supplier continues to maintain the expected quality standards, such as a BI supplier or BI manufacturer’s declaration of conformity to standards. If the user has not established the supplier relationship required to be ensured of consistent  biological indicator performance, additional testing could be necessary until an appropriate assurance can be established that the biological indicators meet the BI manufacturer’s label claim and/or user requirements.

6.1.5 Testing by the user, if deemed necessary, can consist of population assays and defined resistance tests such as D value or survival-kill time on samples from each new batch of biological indicators received (see also 8.6 and Clause 11). Testing should be conducted under exact conditions specified by the manufacturer. Provided that the biological indicator manufacturer produces the based upon detailed standard specifications, i.e., the ISO 11138 series, and the user uses the biological indicator as intended by the biological indicator manufacturer, testing of the resistance characteristics by the user is considered unnecessary.

11.2.1 . . . When tested, the population should be between 50% and 300% of the nominal population. The BI population as labeled by the manufacturer should be used in all calculations following verification. The biological indicator manufacturer should be consulted to ensure that the same techniques and procedures are used because variations in testing procedures can affect the population determination results. ISO 11138-1 requires the manufacturer to provide this information on request.

11.2.5 The user should follow the manufacturer’s recommended procedures for recovery to ensure comparable results.

Mesa Labs’ Recommendations

1. Perform a quality audit(s) of the manufacturer to verify compliance with relevant standards/regulations.
2. Perform population assay on each shipment of BIs to ensure no adverse conditions occurred during shipment.
3. Perform population assays per the manufacturer's instructions.
4. Utilize the Contract Studies Lab at Mesa Labs for all third-party testing.  Mesa Labs Contract Studies Lab provides a variety of testing services including biological indicator population verification and resistance (D-value, z-value, and Survival/Kill times) verification. Since many variables make it difficult to guarantee the ability to reproduce this testing, Mesa Labs, an experienced biological indicator manufacturer, offers these services to customers to support their compliance with standard requirements. The Contract Studies Lab is ISO 13485 certified for these services and functions as an independent lab because its reporting authority is separate from Mesa’s biological indicator manufacturing. 

Additional Resources

1. Spore News SN014 Impact of Culture Media on Biological Indicator Spore Recovery 
2. Spore News SN019 Verification Testing with Different Media is a Waste of Time 
3. Spore News SN022 Heat Shock/Heat Activation
4.  Spore News SN036 BI Label Claim Verification Testing Part I 
5.  Spore News SN039 BI Label Claim Verification Testing Part II
6. TS-401 Population Assay Instructions - Apex® Products  
7. TS-402 Population Assay Instructions– DriAmp® 
8. TS-403 Population Assay Instructions – Paper, Quartz, & Cotton Thread Carrier Products 
9. TS-404 Population Assay Instructions – SterilAmp® II, SterilAmp® II “5230” and MagnaAmp® 
10. S-405 Population Assay Instructions – Spore Suspensions 
11. TS-406 Population Assay Instructions – EZTest® H2O2 and Stainless-Steel Discs 
12. S-407 Population Assay Instructions – ProSpore® 4mL Ampoules 
13. TS-504 Position Statement – Reporting of Authority for Contract Studies 
14. PAK-M: One 250 mL Wheaton bottle containing 240 mL of sterile BD Difco™ Tryptic Soy Agar 
15. PAK-G: Four 19.5 x 145 mm, sterilized, flat bottom, glass tubes with four 6 mm glass beads and caps; Twelve 16 x 125 mm, sterilized, borosilicate dilution blank tubes; Two 10 mL serological pipettes; Two 5 mL serological pipettes; Eight 2 mL serological pipettes; Eight 1 mL serological pipettes 

SN075-V1