Here are 10 factors affecting the efficacy of sterilization and their effects, as identified in the CDC's "Guideline for Disinfection and Sterilization in Healthcare Facilities."
1. Cleaning* — Failure to adequately clean instrument results in higher bioburden, protein load, and salt concentration. These will decrease sterilization efficacy.
2. Bioburden* — The natural bioburden of used surgical devices is 100 to 103 organisms (primarily vegetative bacteria), which is substantially below the 105-106 spores used with biological indicators.
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3. Pathogen type — Spore-forming organisms are most resistant to sterilization and are the test organisms required for FDA clearance. However, the contaminating microflora on used surgical instruments consists mainly of vegetative bacteria.
4. Protein* — Residual protein decreases efficacy of sterilization. However, cleaning appears to rapidly remove protein load.
5. Salt* — Residual salt decreases efficacy of sterilization more than does protein load. However, cleaning appears to rapidly remove salt load.
6. Biofilm accumulation* — Biofilm accumulation reduces efficacy of sterilization by impairing exposure of the sterilant to the microbial cell.
7. Lumen length* — Increasing lumen length impairs sterilant penetration. May require forced flow through lumen to achieve sterilization.
8. Lumen diameter — Decreasing lumen diameter impairs sterilant penetration. May require forced flow through lumen to achieve sterilization.
9. Restricted flow — Sterilant must come into contact with microorganisms. Device designs that prevent or inhibit this contact (e.g., sharp bends, blind lumens) will decrease sterilization efficacy.
10. Device design and construction — Materials used in construction may affect compatibility with different sterilization processes and affect sterilization efficacy. Design issues (e.g., screws, hinges) will also affect sterilization efficacy.
*Factor only relevant for reused surgical/medical devices
Source: CDC
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