Sterility Testing Problems Quiz

Sterilization and Sterility Testing

• Sterilization is the process of destroying all forms of microbial life, including spores.
• Sterility testing is a destructive test that determines if a product is free from living bacteria and fungi, but not viruses.

Problems with Sterility Testing

• Turbid materials: dilution
• Immiscible oils: organic solvent, then direct transfer (DT)
• Creams and ointments: organic solvent, then DT
• Surgical dressing: pieces
• Sterilized devices: wash with sterile saline, then membrane filtration (MF) of saline

Interference with Sterility Testing

• Products with anti-microbial activity:
  • Dilution
  • Antagonism by constituents of media (e.g., mercuric compounds with thioglycolate)
  • Antagonism by addition of sterile materials (e.g., penicillin with penicillinase)

Sterilization of Air

• Less than 2 colonies/cubic feet
• Aseptic areas have:
  • Slightly positive pressure
  • Smooth walls and ceiling
  • Double glass windows
  • Double doors
  • Minimal furniture
  • Sterile air through HEPA filters
  • UV radiation

Methods of Sterilization

• By chemicals (e.g., formaldehyde)
• UV radiation
• Electrostatic precipitation
• Filtration (e.g., cotton or glass wool fibrous pads, cellulose paper filters, cartilage membrane filters)
• Laminar air flow

Microbiological Quality of Pharmaceuticals

• Microbiological quality: level of microbial contamination in pharmaceutical products
• Microbiological quality control (QC): analytical procedure to test for conformity to specification
• Microbiological quality assurance (QA): measures taken during manufacture to ensure product meets specification for microbiological quality
• Good manufacturing practice (GMP): provision of suitable premises, equipment, environment, and personnel to operate approved procedures for production
• Good analytical practice (GAP): as for GMP but for analytical procedures
• Total quality assurance (TQA): net result of GMP, GAP, and QC---product with high quality and error-free

Sterility Testing Procedure

• Sample size: 2% (0.4 N)
• Quantity used per sample: culture media (Fluid Thioglycolate Medium (FTM) and Trypticase Soya broth (TSB))
• Direct transfer (DT) and membrane filtration (MF) methods
• Controls for sterility testing: negative controls and positive controls (standard strains of microorganisms)

Microbiological Quality of Pharmaceuticals (continued)

• Requirements for parenteral preparations: testing for sterility as a QC
• Reasons why a product may prove non-sterile even if sterilized:
  • Absolute sterility is extremely rare due to product integrity
  • Inversely proportional to initial bioburden
  • Resistant contaminants
  • Failure of sterilization procedure due to errors, sterilizer, and incorrect operation
• Requirements for ophthalmic preparations:
  • Contain preservative (Pseudomonas aeruginosa)
  • Be sterile
  • Containers reduce risk of contamination, single dose or small volume
  • Contain preservative
• Microbiological quality of oral and topical preparations:
  • They are non-sterile products
  • Contamination may be due to raw materials, containers, manufacturing environment, and personnel
  • To limit contamination:
    • Appropriate design of premises and equipment
    • Design of SOP (standard operating procedure)
    • Equipment calibration
    • Validation
    • Monitoring the microbial contribution for various elements (in-process control)
    • Preservative tests for pyrogens and bacterial endotoxins in pharmaceuticals