(Operator) Monitoring Sterilization Process Indicators Quiz

Monitoring Sterilization Process

• Physical indicators:
  • Dry heat: thermocouples
  • Moist heat: pressure and vacuum gauge, thermocouples
  • Ethylene oxide: pressure and vacuum, thermocouples, humidity
  • Radiation: dosimeter
  • Filtration: bubble point pressure technique
• Chemical indicators:
  • Bowne's tube: chemical change in color, ester hydrolysis
  • Witness tube: compounds melt at sterilization temp (e.g. sulfur at 115°C, benzoic acid at 120°C)
• Biological indicators:
  • Dry heat: Bacillus subtilis or Clostridium tetani
  • Moist heat: Bacillus staerothermophillus
  • Ethylene oxide: Bacillus globigii
  • Ionizing radiation: Bacillus pumilus
  • Filtration: Serratia marcescens or Pseudomonas diminuta
• Mathematical indicators:
  • Increased D value: resistant
  • Increased Z value: resistant
  • Increase in either D or Z values: re-evaluation of sterilization cycle

Validation of Sterilization Process

• Bioburden monitoring: total number of organisms per milliliter or per gram
• Environmental monitoring: microbial contamination in manufacturing areas
• Monitoring sterilization process: physical, chemical, biological, and mathematical indicators
• Monitoring sterilized product: to ensure product is sterilized

Cold Sterilization

• Types: radiation, filtration, and gaseous sterilization
• Ethylene oxide:
  • Mode of action: alkylation of sulfhydryl, amino, hydroxyl, and carboxyl groups in proteins and imino groups in DNA
  • Properties: gas at normal pressure, inflammable, explosive, toxic, mutagenic, and carcinogenic
  • Factors affecting efficiency: concentration, temperature, relative humidity, and penetration
  • Application: suitable for plastic, antibiotics, hormones, surgical dressing, and thermolabile powders in bulk

Radiation Sterilization

• Mode of action: release electrons from atoms, target effect, and indirect effect
• Types: gamma rays, accelerated or high-speed electrons, and UV radiation
• Radiation dose: 2.32 million rad (M.Rd) or 25 kGray
• Application: similar to ethylene oxide and vaccines

Sterilization by Filtration

• Use: for thermolabile liquids, gases, and solutions
• Advantage: removes microorganisms, does not alter physicochemical characteristics of the substance
• Disadvantage: aseptic, bacterial toxins not removed, and requires trained staff
• Types: depth filter and screen filter