For the majority of the last one hundred years, microbiology laboratory methods have remained relatively unchanged, with tests being based on culture media and the foundations that were laid down by the pioneers of microbiology: Pasteur and Koch. It’s only relatively recently that the fundamental basis of testing has begun to change; as a result, rapid and alternative microbiological methods have emerged.
Unfortunately, uptake in the pharma and healthcare industries has been slow. Companies in the field all appear to be waiting for someone else to make the first move, but the time to move is now. The cost of the technology, validation requirements and time required for implementation may be a hindrance, but one obstacle that has been removed is regulation. Indeed, regulatory bodies like the UK MHRA and the US FDA have expressed a keen desire for the industry to adopt more accurate microbiology systems. New systems are certainly more accurate – and faster (traditional cultural methods can take weeks, rapid systems typically take hours or only a few days) – as well as providing other benefits. Rapid microbiology methods also overcome the difficulty (and risk) of ‘viable but non-culturable’ microorganisms. Many bacteria, despite maintaining metabolic activity, are non-culturable due to their physiology, fastidiousness or mechanisms for adaptation to the environment. Such types of microorganisms could exist in a medicinal product but they are not detectable using established culture-based test methods. On the other hand, several rapid methods are not reliant upon growth media and they can detect almost all of the organisms present within a product. Rapid methods are not only suitable for finished products; they can also be used for screening the raw materials and water that go into making medicinal products; for testing intermediate samples of products as they are being manufactured; and for assessments of environmental monitoring during the manufacturing process. Tantalizingly, we can now have complete confidence in microbiological quality throughout the whole pharmaceutical operation. Rapid microbiological method technologies aim to provide more sensitive, accurate, precise and reproducible test results when compared with conventional, growth-based methods – and they are simpler and quicker to run. In essence, microbiologists get better results with higher throughput and lower error – all of which should lead to increased medicine safety for patients.
Rapid microbiological methods can be divided into four categories:
- Qualitative tests for the presence or absence of microorganisms. For example, using DNA probes that screen for the presence of E. Coli in water.
- Quantitative tests for enumeration of microorganisms. Such methods include those that directly label individual cells with viability stains or fluorescent markers or optical spectroscopy methods that utilize light scattering and other optical techniques to detect, enumerate and identify microorganisms.
- Quantitative tests for potency or toxicity. An example here is turbidimetric methods for bacterial endotoxin.
- Identification tests. Methods include looking at regions of microbial DNA and taking genetic fingerprints, which can then be compared to library profiles to identify a microorganism.
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