What is Disinfectant Validation? 2

The CEN TC 216 methodology has three phases to its Disinfectant Effectiveness Test—European Tiered Test Approach (see Table II).
As a result of the CEN TC 216 work program, and with the concurrence of the EU Biocides Directive, several BS EN (European Standards as adopted by the British Standards Institute, test methods have been issued. These pass–fail test methods detail how disinfectants should be tested against selected cultures under controlled laboratory conditions. They also require an evaluation of the laboratory test results against field test results (see Table III).
Disinfectant effectiveness tests are not yet routine, so most drug-industry microbiologists are unfamiliar with them. The protocols take a long time to learn and a long time to perform, which makes them expensive. In addition, they are difficult to do and are done infrequently, which makes it hard to maintain laboratory personnel proficiency and hard to produce reproducible results.

Table III: British Standards (BS) EN test methods.

Reproducibility is critical to proper interpretation of results. Variability in AOAC`s tests is mostly caused by errors in preparing test solutions and media. Some studies have shown, however, that the AOAC testing technique (3, 4) and inoculum preparation (5) may also be at fault. Variations in conditions during cold storage (i.e., refrigeration, freezing, freeze-drying) can affect the predominant genotype in the stock culture or source culture (6). Thus, when pharmaceutical companies try to validate disinfection processes using AOAC protocols, they may be unable to reproduce the disinfectant manufacturers' bactericidal label claims. CEN TC 216 tests are also liable for reproducibility problems caused by variation in the inoculum size and preparation (7, 8). In the United States, the EPA shares regulatory authority with FDA, which has jurisdiction under 21 CFR 880.6890, General purpose disinfectants. This Subpart (concerned with medical devices), defines a general purpose disinfectant as a "germicide intended to process noncritical medical devices and equipment surfaces." (Noncritical medical devices make only topical contact with intact skin.) Liquid chemical sterilizers intended for use on critical or semicritical medical devices are defined and regulated by FDA under 21 CFR 880.6885, Liquid chemical sterilants/high-level disinfectants.
Sanitation process validation

Definitions and distinctions

A review of regulatory definitions (see sidebar, "Definitions and Distinctions") quickly leads to the realization that "disinfectant validation" is actually equivalent to sanitation process validation. This analysis leads to the following proposal for improving the validity of the validation process while making it easier and less time-consuming to perform. This approach is based on the CEN TC 216 work program methodology for registering disinfectants in the European Union and on the quantitative carrier tests (QCT) developed by the University of Ottawa for environmental surfaces and medical devices (9). Like the CEN TC 216 method, the Ottawa QCTs first assess microbicidal performance under ideal conditions, and then move on to assess field performance with more stringent tests.