Kills mycobacterium and all less- resistant organisms but not all spores.

Various test organisms used for validation.

Designed to kill up to 6 logs of mycobacterium.

6 logs = 106 = 1,000,000

Sponsored by

Table 1 — Comparison of flexible endoscope reprocessing methods High-Level Disinfection

Liquid Chemical Sterilization

Kills all organisms, including spores.

Various test organisms used for validation.

Designed to kill up to 6 logs of mycobacterium, including spores.

(10x10x10x10x10x10) 6 logs = 106

(10x10x10x10x10x10) = 1,000,000

SAL not applicable

Performed with manual soak method or automated reprocessor.

Provides a wet, high-level disin- fected item.

Effectiveness dependent on effec- tive cleaning and complete drying of device prior to storage.

Quality control monitoring tools:

• Physical parameters • HLD minimum effectiveness concentration indicator

SAL not applicable

Performed in automated liquid chemical sterilant reprocessing system.

Provides a wet, liquid sterilized item to be used immediately. If stored, must be reprocessed directly before use.

Effectiveness dependent on effec- tive cleaning. Device wet when used on patient. Complete drying required prior to storage as an HLD device.

Quality control monitoring tools:

• Physical parameters • HLD minimum effectiveness concentration indicator

Note: One method provides a spore test strip.

(EO) have been studied and characterized extensively. A terminal sterilization process with an SAL of 10-6

has the probability that

only one organism in one million survived. It is the predictable, linear behavior that allows the terminal sterilization ‘overkill’ process or ‘safety factor’ to be provided. Terminal sterilization process cycle time is based on the point at which the biological indicator of a resistant spore is dead, and the time is then doubled. It is this extra time and predictability of cycle that provides the safety factor for terminal sterilization processes that are run in a sterilizer. See Figure 1. In contrast, data shows that liquid processes don’t show a linear kill process.26 Table 1 provides a comprehensive com- parison of the chemical processes using liquid and gaseous chemical sterilants for consideration. For sterilization of flexible endoscopes, the following factors may also be considered in determining the best method for the health- care facility to use: • margin of safety (or ‘overkill’) of the pro- cesses

• efficacy of processes to penetrate long lumens/channels of the endoscopes

• endoscope manufacturer’s validation of the process as documented in the IFU

Low-Temperature Terminal sterilization

Kills all living organisms, including spores.

Specific spore type defined in stan- dards used for validation.

Designed to kill 12 logs of most resistant to the process spores as defined in standards. 12 logs = 1012

(10x10x10x10x10x10x10x10x10x 10x10x10) = 1,000,000,000,000

Linear process with a defined Sterility Assurance Level (SAL) of 10-6

or higher Performed in a sterilizer.

Provides a sterile, packaged item that maintains sterile barrier until used or packaging is compromised

Effectiveness dependent on effec- tive cleaning and complete drying of device prior to packaging.

Quality control monitoring tools:

• Physical parameters • External and internal chemical indicators • Biological indicators used in a process challenge device

• endoscope material compatibility with the chemical process

• length of the cycle • quality control system that is or is not available for the process

• cost of the process • evidence that the process is effective at halting endoscope related outbreaks

Summary Effective flexible endoscope reprocessing is a challenging task with many complexities and considerations. Patient outbreaks and evidence of patient-ready contaminated endoscopes have been well documented in the literature and standards. Users should understand that satisfactory cleaning, inspection and drying is always required and critically important for successful dis- infection, liquid sterilization or terminal sterilization. Terminal sterilization processes are designed and validated with an overkill or ‘safety’ factor and provide a significantly higher level of lethality compared to liquid processes. The type of process used for sterilization of a flexible endoscope should be based on the endoscope manufacturer’s IFU as the manufacturer has validated the reprocessing recommendations. Evidence shows that several of the duodenoscope-


related outbreaks were effectively halted when the facility switched from high-level disinfection to a terminal sterilization pro- cess using EO. HPN


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