The limits of sterility assurance.

Area of Science:

• Microbiology and Sterilization Science
• Medical Device Reprocessing
• Pharmaceutical Manufacturing

Background:

• Sterility Assurance Level (SAL) of 10(-6) is the current standard for pharmacopoeial sterilization.
• Achieving and verifying SAL 10(-6) is practically difficult and potentially unnecessary for certain applications.
• Current standards may not align with patient safety, cost-effectiveness, and energy efficiency.

Purpose of the Study:

• To critically evaluate the universal application of SAL 10(-6) for sterilization procedures.
• To propose a tiered SAL concept for sterilization based on intended use and product characteristics.
• To ensure patient safety while optimizing sterilization processes for efficiency and cost.

Main Methods:

• Analysis of theoretical SAL requirements versus practical limitations in sterilization.
• Consideration of contamination probabilities in aseptic processing and automated systems.
• Evaluation of reductions achieved through cleaning, disinfection, and sterilization of medical devices.

Main Results:

• A universal SAL of 10(-6) is practically unattainable for non-thermal sterilization methods.
• Tiered SALs, analogous to disinfection levels, can be determined based on product application and treatment options.
• Proposed tiered SALs: SAL 10(-6) for 'Pharmaceutical sterilization', SAL 10(-4) for 'High-level sterilization' (heat-resistant devices), and SAL 10(-3) for 'Low-level sterilization' (heat-sensitive devices with validated cleaning).

Conclusions:

• Adherence to a single SAL 10(-6) may not be scientifically or practically justified for all sterilization tasks.
• A tiered SAL system offers a more pragmatic and safety-conscious approach to sterilization.
• Implementing tiered SALs can lead to improved safety, cost-effectiveness, and energy efficiency in sterilization processes.