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Sterilization & Disinfection, Disinfection - Coggle Diagram

- - - - Dry heat
        
        Excessive heat denatures protein
      - Moist heat
        
        Pressurized moist heat (steam) most dependable physical method for destruction of all forms of microbial life
        
        Autoclave
        
        Bench top autoclave
        
        Gravity dispensing autoclave
        
        Household pressure cooker/ Wisconsin
        
        Pre-vacuum autoclaves "flash autoclave"
        
        Process
        
        Heating water to form steam
        
        Air heavier than steam
        
        Gravity used for evacuation of air from chamber
        
        Steam in confined space incr pressure
        
        Incr pressure incr temp
        
        Higher temp causes more steam
        
        Steam condenses on items in chamber
        
        Heat released
        
        Steam under pressure penetrates porous items
        
        Denatures faster & @ lower temp compared to dry heat
        
        Load AC correctly > steam able to move bt packs & avoid overfilling & air pockets
        
        Min time & temp for effective steri
        
        Instruments alone > 15min @ 121C
        
        Drapes/linen > 30min @ 121 - NBNBNB
        
        Clean instruments prior to sterilization
    - - Gamma
        
        Expensive & needs purpose trained staff
        
        Penetrates easily > prepacked items
        
        Short wavelength, high E rays
        
        Gloves, catheters, suture material, etc.
      - UV
        
        Airborne microbes & directly exposed surfaces sterilized effectively
        
        Undersurfaces, dust particles, pores of drapes not
        
        Poor penetrating ability
        
        Discouraged
  - - - Ethylene oxide
        
        Cycle: air evac > humidification > gas entry > gas evac > air entry
        
        12 hrs @ room temp or 4 hrs @ 550C
        
        Gas chamber sterilizer
        
        MOA = Alkylation (H+ substituted for alkyl grp)
        
        Advantages
        
        Extremely broad spectrum (against all micros)
        
        Non-corrosive (any material)
        
        Sterilize delicate surg instruments (opthalm)
        
        Disadvantages
        
        Expenny: equipment & running costs
        
        Flammable, explosive (unless mixed w/ CO2)
        
        Toxic (ammonia like)
        
        Ventilation systs mandatory for aeration of room
        
        No personnel allowed in room
        
        Carcinogenic
        
        Long exposure times & aeration needed
      - Formaldehyde
        
        Closed plastic container
        
        Cheap & easy
        
        Ambient temp liberates formaldehyde gas
        
        Formaldehyde + water = formalin (microbicidal) against gram +ve & gram -ve bacteria, all fungi, viruses, mycobacteria & bacterial spores
        
        Tablet/granules
        
        MOA
        
        Aldehydes potent seekers of N2
        
        All microbes have N2
        
        Aldehydes form strong, irrev bonds to N2
        
        In bacterial cell proteins & enzymes
        
        Kills & fixes the cell contents
        
        @ 22C-24C & 73% humidity for 24hrs
        
        Advantages
        
        Broad spectrum
        
        Cold sterilization or gas sterilization
        
        Inexpensive, simple to use in practice
        
        Rapidly microcidal
        
        Disadvantages
        
        Noxious fumes
        
        Allergic rxns (asthma, skin irritations)
        
        Can only be used on inanimate objects
    - - Aldehydes
        
        Stabilized glutaraldehyde's
        
        Mixture of chemical buffers & detergents
        
        Active, non-volatile
        
        No base req for activation
        
        Negligible skin irritation
        
        Straight from bottle > G-cide
        
        Quicker > 4 hrs
        
        Extended shelf life
        
        Formalin > irritant & not used
        
        Glutaraldehyde
        
        Once activated highly cidal & volitile
        
        Stability lasts 3 weeks
        
        Activated by addition of base: sodiumbicarbonate, sodiumhydroxide (Rise pH to 8 to activate)
        
        Used for flexible endoscopes (10hrs)
        
        Stable 2% acid solution (Cidex) > cold steri
        
        Less irritant
      - Medistel concentrate
      - Peracetic acid
        
        Sterilize inanimate objects that cant be exposed to heat/steam
        
        More potent antimicrobicidal than H202
        
        Rapidly active @ low conc against wide spectrum micros
        
        Non toxic residues
        
        Sporocidal even @ v low temps
        
        Remains effective in presence of OM
        
        Effective biocide
        
        MOA
        
        Peracetic acid as disinfectant oxidizes outer cell membs of micros
        
        Oxidation mech consists of e- transfer
        
        Stronger oxidant used e- transferred to microorg faster > deactivated rapidly
- - - - Prevention of post op infection
      - Forms basis of aseptic technique
  - - - Intact skin of patient
      - Hands of surgeon
    - - Poor aseptic techinque
      - Long surg procedures
      - Laryngo/bronchoscopes
      - Old age/chronic disease
      - IV & urinary catheters
- - - - Surface acting cleansing agent
      - Dissolves (emulsifies) fats & oils
      - Allows them to be washed away
    - - Salts formed bt A&B
      - Anionic, cationic or non-ionic
- - - - Chlorinated lime for disinfection of hospital wards
      - Hypochlorite destroys pure cultures of bacteria
      - Chlorinated lime for treatm of sewage
      - Na+ hypochlorite (0.45%-0.5%) for disinfection of open & infected wounds (USOL solution)
    - - Damages cell membs & enzymes
      - Bacteriocidal
      - HOCL dissociates > H+ + OCl- >> both active
      - Chlorine + water > hypochlorous acid (HOCL)
    - - Hypochlorites
      - Liquid chlorine & chlorine dioxide