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Sterilisation (Physical (Filtration (Sterilisation of liquids (Sintered…

- - - - Red heat
        
        Kill endospores and vegetative cells
      - Flaming
        
        Kill vegetative cells only
      - Incineration
        
        Destroy contaminated objects
      - Hot air oven
        
        BP recommended: 160 °C, 2 hours
        
        Only suitable for heat stable particles - oils and powders (dry preparations)
      - Death of microbes by oxidation
      - Indicators refer lecture notes
    - - Not suitable for dry preparations
      - Higher thermal capacity
      - <100°C: Pasteurization
        
        Holder method - low temperature longer time 63°C,30 minutes
        
        Flash method - high temperature shorter time 72°C, 15 seconds
        
        Ultra-High Temperature (UHT) - 135°C for 1-2 seconds
        
        Food and diary indurstry
      - 100°C: Tyndallisation/Fractional sterilisation/Intermittent sterilisation
        
        Sugar,milk,gelatin
        
        100°C for 20 minutes, followed by incubation at 37°C overnight - 3 successive days
        
        Sporicidal
      - 100°C: Autoclaving
        
        Standard sterilisation method in hospital
        
        at high pressure
        
        BP recommended: 121°C at pressure of 15psi for 15-20 mins
        
        Heating phase: remove air and replace with steam
        
        Holding phase: sterilisation takes place
        
        Cooling phase: Return to atmospheric pressure and drying
      - Death of microbes by coagulation and denaturation/ hydrolysis of proteins in cell
      - <100°C : Inspissation
        
        Stiffening of protein without coagulation
        
        75-85°C for 30 minutes on 3 successive days
      - Factors
        
        Time
        
        Temperature
        
        Shorter the time of exposure, the higher the temperature must be employed
        
        Steam contact
        
        Steam quality
        
        Wet steam
        
        Decrease amount of energy
        
        Superheated steam
        
        Decrease area of steam contact
        
        Air removal
        
        Gravity displacement
        
        Vacuum method
        
        Drying
      - Indicators refer lecture notes
  - - - High speed electron beams
        
        Poor penetration
        
        Sophisticated equipments
      - Gamma rays
        
        High penetration
        
        Require longer time for exposusre
        
        25 kGy kills all microorganisms
        
        Also referred to as cold sterilisation
      - For heat-sensitive pharmaceuticals
    - - UV ray
        
        Poor penetration and low energy
        
        260 nm is the most effective
        
        Induce formation of thymine-thymine dimers and inhibits DNA replication
        
        Do not kill spores
        
        Disinfect hospital wards,corridors,labs etc.
  - - - Sintered glass
      - Asbestos
    - - made of cellulose
      - fluids transverse through membranes by pressure or centrifugation
    - - Sintered filter are used for corrosive,viscous and organic solvents
      - 0.01μm : for small viruses
      - 0.22μm: critical sterilisation for parenteral solution
      - 0.45-.80μm: bacteria and yeast
    - - HEPA filters can remove >0.3μm of microbes (bacteria and yeast)
      - Efficiency is monitored by dioctylphthalate (DOP) particle test that are 0.3μm in diameter
      - Used in laboratory hoods and rooms of immunocompromised patients
    - - Determine the pore size of filter
      - Check the integrity of membrane