SIST EN ISO 11138-4:2017 PDF

Overview

EN ISO 11138-4:2017 - "Sterilization of health care products - Biological indicators - Part 4: Biological indicators for dry heat sterilization processes" - specifies production, test methods and performance requirements for biological indicators (BIs) used to validate and monitor dry heat sterilization (120 °C to 180 °C). Adopted by CEN as EN ISO 11138-4:2017, this edition supersedes the 2006 version and provides updated criteria for BI manufacture, resistance characterization and packaging suitability.

Key topics and technical requirements

• Test organisms: Spores of Bacillus atrophaeus (or equivalent strains with demonstrated performance).
• Population: Inoculated carriers and BIs must contain ≥ 1.0 × 10^6 viable spores per unit.
• Resistance metrics:
  • D value (decimal reduction time) is reported at 160 °C, to one decimal place; minimum D ≥ 2.0 min for B. atrophaeus when tested per Annex A.
  • z value (temperature change for tenfold change in D) must be determined from at least three temperatures in the 150–180 °C range and z ≥ 20 °C (see Annex B for calculation).
• Test methods and equipment: Determination of D and survival–kill characteristics requires a resistometer using the reference resistometer process parameters (Annex A). D values are determined per ISO 11138-1 annexes.
• Carrier and primary packaging suitability: Manufacturers must demonstrate carrier/packaging stability under specified exposure conditions (dry heat in ambient air), including a challenge at ≥ 5 °C above stated maximum and a minimum exposure time of 30 minutes; if no maximum temp is stated, assume ≥ 180 °C.
• Documentation: Resistance characteristics, viable counts (increments ≤ 0.1 × 10^n), and batch/lot D values must be declared with the BI.

Practical applications

• Validation and routine monitoring of dry heat sterilizers used for medical devices and healthcare products (e.g., glassware, metal instruments).
• Manufacture and quality control of biological indicators and inoculated carriers.
• Laboratory testing to determine BI for product specification and comparison.