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61 MICROBIOLOGICAL EXAMINATION OF NONSTERILE PRODUCTS（非灭菌产品的微生物检验）: MICROBIAL ENUMERATION TESTS （微生物菌数测定试验） INTRODUCTION （介绍） The tests described hereafter will allow quantitative enumeration of mesophilic bacteria and fungi that may grow under aerobic conditions. The tests are designed primarily to determine whether a substance or preparation complies with an established specification for microbiological quality. When used for such purposes, follow the instructions given below, including the number of samples to be taken, and interpret the results as stated below. The methods are not applicable to products containing viable microorganisms as active ingredients. Alternative microbiological procedures, including automated methods, may be used, provided that their equivalence to the Pharmacopeial method has been demonstrated. GENERAL PROCEDURES（一般程序） Carry out the determination under conditions designed to avoid extrinsic microbial contamination of the product to be examined. The precautions taken to avoid contamination must be such that they do not affect any microorganisms that are to be revealed in the test. If the product to be examined has antimicrobial activity, this is, insofar as possible, removed or neutralized. If inactivators are used for this purpose, their efficacy and their absence of toxicity for microorganisms must be demonstrated. If surface-active substances are used for sample preparation, their absence of toxicity for microorganisms and their compatibility with any inactivators used must be demonstrated. ENUMERATION METHODS（菌数测定方法） Use the Membrane Filtration method or one of the Plate-Count Methods, as directed. The Most-Probable-Number (MPN) Method is generally the least accurate method for microbial counts; however, for certain product groups with very low bioburden, it may be the most appropriate method. The choice of a method is based on factors such as the nature of the product and the required limit of microorganisms. The method chosen m