RAPID METHODS SUPPLEMENT


DETECTION OF MICROORGANISMS


Michael J. Miller President, Microbiology Consultants, LLC


This is the fifth in a series of articles on Rapid Microbiological Methods (RMMs) that will appear inEuropean Pharmaceutical Reviewduring 2011. Previously, we reviewed a relatively new set of rapid methods that are based on optical spectroscopy. Because these systems do not rely on microbial growth, the time to result is virtually instantaneous, which meets the goal of real-time Process Analytical Technology (PAT) solutions for pharmaceutical microbiology applications. In the current article, we will review one of the fastest growing segments in the rapid methods world: nucleic acid and gene amplification technologies for the detection, identification, and in some instances, the enumeration of microorganisms.


Nucleic acid and gene amplification tech - nologies (also known as genetic or molecular methods) are now recognised as providing superior results when compared with other microbiology methods for particular types of assays. For example, there is a growing trend that more and more pharmaceutical companies are implementing genetic methods for microbial identification and detection applications due to their greater accuracy, speed to result, automation and throughput as compared with classical methods. And the regulatory authorities have also acknowledged the advantages in these types of rapid


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European Pharmaceutical Review Volume 16 | Issue 5 | 2011


methods. The FDA Aseptic Processing Guidance recommends the use of rapid genotypic methods for microbial identification, as these methods have been shown to be more accurate and precise than biochemical and phenotypic techniques, and they are especially valuable for investigations into failures (e.g., sterility test; media fill contamination). Both the European and Japanese Pharma - copeias now recommend PCR for Mycoplasma testing, and the Australian Therapeutic Goods Administration (TGA) requires that a sensitive method of microbial identification, such as molecular typing techniques utilising RNA/DNA


homology, is utilised when the identification of an isolate is used to invalidate a sterility test. Nucleic acid and gene amplification


technologies utilise a number of scientific principles, including different types of polymerase chain reaction (PCR), transcription- mediated amplification, 16S rRNA typing (ribotyping), and gene sequencing of specific targets of interest, to name a few. Many of these methods have been designed to rapidly detect the presence of a specific microorganism (e.g., an objectionable or specified ‘compendial’ organism), or generate data that can be used to determine the identification of a recovered microbial isolate, from the Genus level down to the sub-species and/or strain level. Additionally, for systems that utilise amplification platforms, the number of amplification cycles to reach a certain threshold level can now be used to estimate the number of organisms in the original sample. Although there is not enough space to discuss all of the available technologies in this article, I will provide an overview of the most


USING NUCLEIC ACID AND GENE AMPLIFICATION- BASED RAPID METHOD TECHNOLOGIES


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