Ph. Eur. chapter 5.1.6, Alternative Methods for Control of Microbiological Quality, describes alternative methods for the control of microbiological quality. A discussion of qualitative, quantitative and identification tests and guidance for using validation criteria are provided. Additionally, technology overviews including risk-benefit analysis and an annex describing an example of a detailed protocol for the validation of an alternative method using bioluminescence techniques have been proposed.
Abstract “European Pharmacopoeia (Ph. Eur.) general chapter 2.6.7. Mycoplasma requires for the culture test reference strains of mycoplasma field isolates with fewer than 15 passages for validation and run control and in the test for inhibitory substances. Low passage field isolates of 5 mycoplasma strains (Mycoplasma hyorhinis, Mycoplasma synoviae, Mycoplasma fermentans, Mycoplasma orale and Acholeplasma laidlawii) have been prepared for this purpose and a small scale collaborative study involving European laboratories was carried out to confirm the suitability of the material for the intended purpose. Strains were prepared as 1 ml samples in frozen format and are stored below -60 degrees C. Each laboratory determined a titre for the material on their in-house media. A secondary part of the study also compared the growth of prediluted samples on the different culture media. Results of the study confirm that the material is suitable for use as a biological reference preparation (BRP) and an estimated titre has been provided for each strain based on the results of the study. It was noted that differences in the culture media used in the different laboratories did not have a detrimental effect on titre estimation. The estimated titre is intended as a guide for users to validate the use of the reference material in house. The candidate BRPs were adopted by the European Pharmacopoeia Commission on June 28, 2006 and are available for use from EDQM. A revision to chapter 2.6.7, including reference to the use of nucleic acid amplification techniques (NAT) was also adopted in June 2006 and will appear in the European Pharmacopoeia version 5.8 in January 2007 and come into force the 1st of July 2007. While it was not part of the study a number of participants also performed in-house NAT assays on the study material. Preliminary findings from these studies are presented.“
Nucleic acid amplification techniques
USP informational chapter <1223>, Validation of Alternative Microbiological Methods, provides guidance for the validation of methods for use as alternatives to official compendial microbiological methods. The chapter incorporates the analytical concepts from USP <1225>, Validation of Compendial Methods, and relates these to alternative quantitative and qualitative microbiological systems. Although there is no guidance on qualifying new microbial identification systems, the USP has recently published a separate draft informational chapter on this topic.
This chapter provides guidelines for the validation of methods for the estimation of the number of viable microorganisms, for the detection of indicators or objectionable microorganisms, for the validation of microbiological methods used in antimicrobial effectiveness testing, and for the sterility testing of Pharmacopeial articles. It is generally understood that if a product possesses antimicrobial properties because of the presence of a specific preservative or because of its formulation, this antimicrobial property must be neutralized to recover viable microorganisms. This neutralization may be achieved by the use of a specific neutralizer, by dilution, by a combination of washing and dilution, or by any combination of these methods.
Further the chapter gives guidance on handling influential factors, methods of neutralizing antimicrobial properties and validation of neutralizing methods. It is mentioned that we should run 3 replicates and have a recovery of 70%. Or when more replicates are used we should use appropriate statistics (e.g. ANOVA). Additionally it is mentioned that we should think about using injured microorganisms for validation studies. A very interesting table (table 2) is given with the error as a percentage of mean for plate counts.
Using an alternative methodology for the detection of Mycoplasma requires validation and demonstration of comparability to reference standards. A PDA Task Force of experts has developed the PDA Technical Report No. 50, Alternative Methods for Mycoplasma Testing to help your analytical lab feel confident in the use of alternative methods.
The report focuses on non-culture testing methodology, including Nucleic Acid Amplification Technique (NAT) assays and enzyme activity based assays. Representatives of the U.S. FDA and the U.S. Pharmacopeia contributed to the report. The report provides information about existing assays and compendial Methods like NAT based methods and non Nat based methods and describes assay procedures, validation of assays, comparability with reference methods and possible applications.
Human somatic cell therapy and gene therapy products are an emerging class of products that present multiple challenges to safety, purity and potency. Gene therapy products (see definition in section II.D.2), include vectors (i.e., nucleic acid, virus, or genetically modified microorganisms) that are administered directly to patients, and cells that are transduced with a vector ex-vivo prior to administration to the patient. Certain genetically modified microorganisms (e.g., bacteria and yeast), cellular therapy products, and cells transduced with a gene therapy vector present similar challenges to sterility assurance. For the purposes of this document these categories of cellular and gene therapy products are called cell-based products. Many cell-based products cannot be cryopreserved or otherwise stored without affecting viability and potency. Most cell-based products are manufactured using aseptic manipulations because they cannot undergo sterile filtration or terminal sterilization (Ref. 2). Rapid and effective testing is needed because many cell-based products have a potentially short dating period, which often necessitates administration of the final product to a patient before sterility test results are available. Because of the challenges associated with cell-based products, there is a significant need to develop, validate, and implement sterility test methods that are more rapid than the sterility test methods described in 21 CFR 610.12.