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STERILIZATION. BY MALEEHA SHAHID 4 TH YEAR MBBS AIMC. OUR ENEMY & COUNTER WEAPON. Microorganisms Invisible Cause infections Sterilization Destruction of all microorganisms Disinfectant Destruction of harmful organisms, or pathogens on nonliving objects. DISINFECTION:.
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STERILIZATION BY MALEEHA SHAHID 4TH YEAR MBBS AIMC
OUR ENEMY & COUNTER WEAPON • Microorganisms • Invisible • Cause infections • Sterilization • Destruction of all microorganisms • Disinfectant • Destruction of harmful organisms, or pathogens on nonliving objects
DISINFECTION: • “The process is intended to kill or remove micr-organisms with exception of bacterial spores”
LEVELS OF DISINFECTION: • LOW: • Reduce over all number of vegetative micro-organisms BUT don’t destroy tuberculosis & spores • Used: for environmental surfaces • INTERMEDIATE: • Kills tubercle bacilli, most viruses, fungi & some spores: • Use: horizontal surfaces & floor of OT • HIGH: • Kills most forms of microbes including tubercle bacilli but not some spores. • Used: flexible endoscopes
Disinfectants • Types of disinfectants • Bactericides • Fungicides • Germicides • Virucides • All prevent transfer of infection
STERILIZATION: • “The process destroys all forms of micobial life including bacteria, viruses, spores and fungi”. • Characteristics • Active against pathogens • Non-irritating • Cleansing • Cost-effective • Long shelf life • Safe for patient and handler • Stable in the presence of organic matter
Sterilizing Agents • Type of agents • Chemical • Physical • Moist heat • Dry heat • Most clinics use physical agents
Moist heat • Steam and boiling water • Alone not effective • Captured steam effective • Autoclave • Sealed chamber that furnished both heat and pressurized steam for sterilization • Inexpensive • Sterilizes • Instruments • Syringes • Needles • Other materials
Dry heat • Slow sterilizer • Higher temperatures • Penetrates • Oil-based materials • Closed containers
Direct flame • Can also dip in Alchohol & flame • Can damage the exposed object
Time/Temperature Relationship • Most important factor in destroying microorganisms is length of exposure to heat • Varies with microorganisms • The higher the temp the faster it will kill microorganisms exposed • Temps lower than boiling point can sterilize some medications and milk
Other Sterilization Technology • Filtration • Ultraviolet irradiation • Cold sterilization • Ethylene oxide
Filtration • Complete removal of microorganisms and particles of a certain size from liquid or gas • Used by personnel in producing sterile and particle-free fluids, such as intravenous fluids
Ultraviolet irradiation • Destroys microorganisms in air, liquid, and surface • Germicidal UV radiation is generated by passing electricity through mercury vapor in special glass tubes • UV lamps sterilize most effectively in still air at room temperature
Cold sterilization • Gamma radiation • Kill microorganisms without a rise in temperature • Highly successful in sterilizing • Syringes • Stitching (sutures) materials • Containers
GAMMA PROS & CONS • Pros • Well characterized parametric (fast) release • Penetrates well • Most materials OK • Cons • More expensive than EO • Not in-house process • Yellowing and embrittlement of some polymers
ETHYLENE OXIDE PROS & CONS • Pros • Most materials compatible • Relatively low temperature process • Most packaging materials OK • Relatively low cost • Cons • Penetration sometimes difficult • Residuals • Batch process • Long process and release time
STEAM PROS & CONS • Pros • More tolerant material available • More packaging choices • Relatively inexpensive • Often used in-house • Cons • Batch process • Few polymer-based devices work • Some maintenance costs
MONITORING STERILIZATION: • Use of indicators: • Bowie – Dick Test • Browne’s Tubes or • Impregnated Tapes
Browne's tubes • Glass tubes containing red liquid that changes to green after successful sterilisation. Available in two ranges, the black stop tubes changing colour after 20 minutes at 121�C, the green spot after 60 minutes at 160�C.