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发表于 2013-9-5 13:44:54
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玻璃杯 发表于 2013-9-5 13:31 
微生物培养有固有的可变性(0.5个log值)
这句话怎么理解?百度下,没答案呀,谢谢指教
Quantitative data offer different challenges to the microbiologist. There are differences in the variation of microbiological data due to sample variation, population variation and assay variation. In addition, these counts are subjective because of the influence of sampling, growth media, and incubation parameters. The technical assessment of these data has a subjective element that frustrates clear, objective decision making. Acknowledgement of these is the first hurdle for the analyst. USP <1227> Validation of Microbial Recovery from Pharmacopeial Articles offers suggestions for the interpretation of results from various conventional tests that begin with a common and fixed sample and population. Many analysts mistakenly assume that if one can distribute samples from a single dilution tube and get values for multiple culture plates that conform to a tight range (small value for sigma) then multiple samples should also conform to that same tight range. This confuses sample variation and assay variation. Test methods are often validated using cultures prepared on the same growth medium as used by the method that will be tested. In practice, the microorganisms from pharmaceutical samples are diverse, and are not in the robust metabolic state as the laboratorycontrived samples. Furthermore, the variable distribution of microorganisms in samples may produce a wide range of counts, and when these counts are small, they can vary by multiples. |
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