Overview
EN ISO 24072:2023 (ISO 24072:2023) specifies an aerosol bacterial retention test method for assessing the bacterial retention ability of finished stand‑alone and integrated air‑inlet filters used on administration devices for infusion and transfusion. The method simulates a clinical aerosol challenge using a Staphylococcus aureus aerosol to quantify how many microorganisms can pass through an air‑inlet filter under defined, more stringent conditions than normal clinical use.
Key topics and technical requirements
- Test principle: Challenge with a Staphylococcus aureus aerosol and measure bacteria passing through the air‑inlet filter using liquid impingers and colony counting.
- Aerosol characteristics: Aerosol generator calibrated to produce a mass median aerodynamic diameter (MMAD) of (2.5 ± 0.5) μm with a geometric standard deviation (GSD) ≈ 1.8.
- Challenge organism and preparation: Staphylococcus aureus ATCC 6538™ (or equivalent), incubated in TSB/NB at (32.5 ± 2.5) °C for 18–24 h and diluted to validated concentration.
- Apparatus: Aerosol generator and chamber, sample test housing (designed for stand‑alone or integrated filters), liquid impingers with collecting fluid (sterile saline), flowmeter and vacuum pump.
- Flow conditions: Test flow set and controlled at 50 ml/min (flowmeter accuracy ±5 %) to simulate and exceed infusion‑device air throughput.
- Analytical materials: Tryptone Soya Broth/Agar or Nutrient Broth/Agar for enrichment and counting; analytical filter membrane nominal pore size 0.45 μm.
- Validation and controls: System validation on first use (challenge concentration, spraying time, sampling) and positive control pipeline for comparison.
- Outcome and assessment: Quantify bacteria collected downstream to calculate bacterial retention ability. The method is intentionally more stringent than clinical exposure and is generally destructive, making it unsuitable for routine quality control.
Practical applications and users
Who uses EN ISO 24072:2023:
- Medical device manufacturers designing or validating administration devices (infusion sets, transfusion connectors) with air‑inlet filters.
- Contract testing laboratories performing pre‑market verification, product qualification, or failure analysis.
- Regulatory and quality assurance teams requiring standardized evidence of microbial barrier performance.
- R&D teams optimizing filter materials, housing designs, or claims for sterility assurance level.
Typical uses:
- Pre‑market performance testing and design verification
- Comparative testing between filter designs or materials
- Root‑cause analysis when microbial ingress is suspected
Related standards
- ISO 8536‑4 (examples of air‑inlet filter assemblies referenced)
- ISO 11139 (sterility terminology)
- Other bacterial/viral retention test methods (e.g., liquid and aerosol tests such as ASTM F838, ASTM F2101, ASTM F1671) for complementary assessments
Keywords: EN ISO 24072:2023, ISO 24072, aerosol bacterial retention test, air‑inlet filter, administration devices, infusion, transfusion, Staphylococcus aureus, liquid impinger, MMAD, bacterial retention ability.