USP61-微生物限度微生物计数.pdf

58 〈55〉 Biological Indicators—Resistance Performance Tests / Microbiological Tests USP 36 It is preferable to use the same method as that defined by ENUMERATION METHODS the biological indicator manufacturer to determine D values. The use of a different method can result in differences that Use the Membrane Filtration method or one of the Plate- are more an artifact of the method than a variation in the Count Methods, as directed. The Most-Probable-Number performance of the biological indicator. (MPN) Method is generally the least accurate method for microbial counts; however, for certain product groups with Survival Time and Kill Time very low bioburden, it may be the most appropriate method. Take two groups, each consisting of 10 specimens of the The choice of a method is based on factors such as the relevant biological indicator, in their original, individual con- nature of the product and the required limit of microorgan- tainers. Place the specimens of a group in suitable specimen isms. The method chosen must allow testing of a sufficient holders that permit each specimen to be exposed to the sample size to judge compliance with the specification. The sterilizing conditions at a specific location in the BIER cham- suitability of the chosen method must be established. ber. Expose the specimens for the required survival time, enter GROWTH PROMOTION TEST, SUITABILITY the chamber, and remove the holder(s) containing the 10 OF THE COUNTING METHOD AND NEGATIVE specimens. Repeat the above procedure immediately, or preheat if a substantial interval has elapsed, so as to sub