无菌检查方法适用性试验怎么做

结论：先证明方法在你的产品上能检出微生物，检查结果才有意义

无菌检查的逻辑是：把产品接种到培养基中培养，观察有无微生物生长。没有生长就判为无菌。

但这个推论成立有个前提：如果产品中真的有微生物，这个方法能把它检出来。 如果产品本身有抑菌性，微生物即使存在也长不出来，那么「无生长」这个结果就是假阴性——产品实际上有污染，但检查没发现。

方法适用性试验就是验证这个前提。 它证明在该产品存在的条件下，规定量的微生物仍然能够生长并被检出。没有做适用性试验的无菌检查，结果是没有依据的。

试验的基本做法

准备试验菌。 使用规定的菌种，接种量控制在较低水平（少量即可，用于验证方法的检出能力）。

设置试验组。 产品加试验菌加培养基，按实际的无菌检查方法操作。

设置对照组。 只有试验菌加培养基，不含产品。

培养与观察。 按规定条件培养，观察生长情况。

比较结果。 试验组的生长情况与对照组相当，说明方法适用；试验组生长明显受抑制或不生长，说明方法不适用，需要改进。

「与对照组相当」是判断标准。 如果产品存在时菌的生长明显慢于或少于对照组，说明产品有抑菌作用，方法需要调整。

抑菌性的处理

发现产品有抑菌性时，可以采取的措施：

薄膜过滤法加冲洗是最常用的做法，因为它能把可溶性的抑菌物质冲走，只留下截留在膜上的微生物。冲洗量需要通过试验确定——冲洗不足则抑菌性未消除，冲洗过度可能损伤微生物。

采取措施之后要重新做适用性试验，确认措施有效。

方法的选择

薄膜过滤法。 适用于可过滤的液体、可溶解的固体。优点是能通过冲洗去除抑菌物质，对大体积样品也适用。

直接接种法。 适用于不能过滤的产品、器械类产品。操作简单但无法去除抑菌性。

器械类产品的特殊处理。 轮椅、辅具这类产品通常不涉及无菌要求，但某些接触创面的辅料、敷料类产品需要。对于形状复杂或体积大的器械，可能需要用冲洗液冲洗后过滤冲洗液，或者取有代表性的部位检查。

方法的选择要在适用性试验中验证。 选了方法但适用性试验不通过，就要换方法重做。

样品量与取样

检查量。 按产品的规格和批量确定应当检查的数量和每份的取样量。

取样的代表性。 取样应当覆盖灭菌装载中的不同位置，特别是难灭菌的位置。

取样的无菌操作。 取样过程本身不能引入污染。

样品的保存与运输。 从取样到检查之间的条件控制。

「取样的代表性」值得强调。 从容易灭菌的位置取样，检查全部合格，说明不了整批的状况。取样方案应当与灭菌确认的结论对应 ——难点在哪里，就从哪里取。

常见的失败原因

未做适用性试验就检查。 结果没有依据。

适用性试验用的菌种或菌量不当。 菌量过多会掩盖抑菌性。

产品有抑菌性未被发现。 试验设计不当。

冲洗量不足。 抑菌性未完全去除。

操作污染。 检查过程中引入污染导致假阳性。

环境控制不足。 检查应当在适当的洁净环境中进行。

阳性对照未做或失效。 无法确认培养基和条件的有效性。

「操作污染导致假阳性」是实务中的常见问题。 出现阳性结果时，需要调查是产品污染还是操作污染。所以操作过程的记录和环境监测数据很重要 ——它们是调查的依据。

结果的处理

全部阴性。 结合适用性试验的结论，判为符合。

出现阳性。 需要调查：是产品污染还是操作污染。调查内容包括操作记录、环境监测数据、培养基与试剂、人员操作、以及菌种鉴定（污染菌的种类可能提示来源）。

调查结论的处理。 确认为操作污染的可以重新检查；无法排除产品污染的按不合格处理。

「菌种鉴定」在调查中很有用。 某些菌种典型来自人体，某些来自环境，某些来自水系统。鉴定结果能明显缩小调查范围。

与其他工作的关系

无菌检查是终端检验，但它的作用有限：

取样量有限。 检查的是一小部分产品，不能证明整批无菌。

无菌保证主要靠过程。 灭菌工艺的确认与控制才是无菌保证的主要手段。

检查是验证手段之一。 与过程控制、环境监测、初始污染菌监测共同构成无菌保证体系。

所以不能指望用无菌检查来「筛出」污染产品。 检查合格不等于整批无菌，过程控制才是根本。

阳性对照与阴性对照

这两个对照是判断试验有效性的基础：

阳性对照。 只有培养基加试验菌，确认培养基和培养条件能支持微生物生长。如果阳性对照不生长，说明培养基或条件有问题，本次试验无效。

阴性对照（空白）。 只有培养基，确认没有外源污染。如果阴性对照生长，说明操作或环境有污染，本次结果不可信。

这两个对照每次都要做，不能因为「以前都正常」就省略。它们的作用是证明本次试验是有效的，而不是证明方法在一般情况下有效。

环境与人员

无菌检查的操作环境和人员操作直接影响结果：

操作环境。 应当在适当级别的洁净环境中进行，环境的监测数据要保存。

人员培训与考核。 无菌操作技术需要培训并定期考核。

操作记录。 完整记录操作过程，便于出现阳性时调查。

培养基的质量控制。 每批培养基的适用性确认。

器具与试剂的灭菌。 使用的器具和试剂本身要无菌。

「人员考核」在实务中常流于形式，但无菌操作技术的差异会直接体现在假阳性率上。建议用模拟操作的方式定期验证人员的操作水平。

我们的做法

承接无菌相关委托时，我们会先做方法适用性试验，并把试验设计和结果完整记录。 如果产品有抑菌性，我们会说明采取了什么措施、措施是否有效。

对于形状复杂的器械类产品，方法的确定需要与委托方讨论——取样部位、冲洗方式、检查量都要按产品特点确定，没有通用方案。

如果你有无菌产品需要安排检查，或者不确定方法怎么定，可以把产品信息和工艺发过来一起讨论，或者直接联系：132 4819 8029。能力范围见服务介绍，送检要求见送检要求，流程见检测流程。

English version

Conclusion. Sterility testing works by inoculating product into culture media, incubating and observing whether microorganisms grow. No growth is taken to indicate sterility. That inference holds only on one premise: that if microorganisms were present in the product, the method would detect them. Where the product itself inhibits growth, organisms present may fail to grow, and the no-growth result is a false negative, meaning the product is contaminated while the test found nothing. Method suitability testing verifies that premise, demonstrating that a specified quantity of microorganisms still grows and is detected in the presence of the product. A sterility test without suitability testing has no basis.

How the test is performed. Prepare the test organisms using the specified species at a low inoculum, a small quantity sufficient to verify detection capability. Set up the test group with product, organisms and media, following the actual sterility test method. Set up a control group with organisms and media only, without product. Incubate and observe under the specified conditions. And compare: growth in the test group comparable to the control indicates that the method is suitable, while markedly inhibited or absent growth indicates that it is not and requires modification. Comparable to the control is the criterion: growth appreciably slower or lesser in the presence of product indicates inhibitory action and the method must be adjusted.

Handling inhibitory activity. Several measures are available. Increasing the rinse volume suits membrane filtration where the inhibitory substance is soluble. Using a neutraliser suits inhibitory constituents for which a specific neutraliser exists. Increasing the media volume dilutes the inhibitory substance. Changing method, from direct inoculation to membrane filtration, may help. And altering sample preparation adjusts the extraction or dissolution approach. Membrane filtration with rinsing is the most common approach, washing away soluble inhibitory substances while retaining microorganisms on the membrane. The rinse volume must be established by experiment: too little leaves inhibition unresolved, while too much may damage the organisms. After any measure, repeat the suitability test to confirm effectiveness.

Choosing a method. Membrane filtration suits filterable liquids and dissolvable solids, its advantage being removal of inhibitory substances by rinsing and its suitability for large volumes. Direct inoculation suits unfilterable products and device-type items, being simple to perform while unable to remove inhibitory activity. Device-type products need particular handling: wheelchairs and mobility aids generally carry no sterility requirement, while certain wound-contact dressings and materials do. For complex or bulky devices, rinsing with a fluid and filtering the rinsate, or examining representative portions, may be necessary. Whichever method is chosen must be verified through suitability testing; a method that fails suitability must be replaced and the work repeated.

Sample quantity and sampling. Determine the quantity to be tested and the amount per unit from the product's specification and batch size. Ensure sampling is representative, covering different positions within the sterilisation load and particularly the difficult positions. Maintain aseptic technique so that sampling does not introduce contamination. And control conditions between sampling and testing. Representativeness deserves emphasis: sampling from easily sterilised positions and finding everything acceptable says nothing about the batch. The sampling plan should correspond to the conclusions of sterilisation validation, sampling where the difficult positions were found to be.

Common causes of failure. Testing without suitability testing, leaving the result unsupported. Inappropriate species or inoculum in the suitability test, with excessive inoculum masking inhibition. Inhibitory activity going undetected through poor test design. Insufficient rinsing, leaving inhibition unresolved. Operator contamination producing false positives. Inadequate environmental control, since testing requires a suitably clean environment. And positive controls omitted or ineffective, leaving media and conditions unverified. Operator contamination is the frequent practical problem: a positive result requires investigation of whether the product or the operation was contaminated, which makes records of the procedure and environmental monitoring data important as the basis for that investigation.

Handling results. All negative, read together with the suitability conclusion, supports conformity. A positive requires investigation of whether product or operation was contaminated, examining procedural records, environmental monitoring data, media and reagents, personnel technique, and identification of the organism, whose species may indicate its origin. Confirmed operator contamination permits repeat testing, while contamination that cannot be excluded from the product is treated as a failure. Organism identification is valuable in investigation: some species typically originate from people, others from the environment, others from water systems, and identification narrows the investigation considerably.

Relationship to other work. Sterility testing is a final inspection with limited power. The sample size is small and cannot demonstrate that a batch is sterile. Sterility assurance rests principally on process, through validation and control of the sterilisation process. And testing is one verification among several, alongside process control, environmental monitoring and bioburden monitoring. Do not expect sterility testing to screen out contaminated product: a passing test does not mean a sterile batch, and process control is what matters.

How we handle it. For sterility work we perform method suitability testing first and record the design and results in full. Where the product is inhibitory we describe the measures taken and whether they were effective. For structurally complex devices the method must be discussed with the client, since sampling location, rinsing approach and test quantity all follow from the product's characteristics and no general solution exists.

Send us the product information and process and we will work out the method. Phone or WeChat: +86 132 4819 8029.