Disinfection and sterilisation Mongolia 2011 Prof. Dr. Walter Popp Hospital Hygiene, University Clinics Essen, Germany 1 Term Definition Reduction factor of germs Cleaning Remove dirt including 10-100 microorganisms (no need to kill them) by mechanicla means. Mostly wiping with water (and detergents). Sometimes vacuum or highpressure water blaster. disinfection Reduction of number of pathogenic microorganisms so that they are not enough to cause an infection. 1.000 100.000 Sterilisation Killing all bacteria (including spores), mould/fungi, inactivation of all viruses. Every sterile product has to be sterile! 2 1
3 Sterility Definition: Sterile means that a product is free of bacteria, their spores, mould/fungi, viruses must be inactivated, also prions. But: Their is no 100-% safety. Therefore: DIN EN 556 defines a grade of safety (SAL = Sterility Assurance Level) of a sterilisation process for medical devices. Normally SAL of 10-6. This means: A sterilisation process is accepted if there is only one unsterile product in 10 6 (= 1 Million) sterilised products. 4 2
Sterility Testing a new sterilisation process: It is impossible to test 10 6 products. Therefore testing with bacteria which are hard to sterilise, measuring physical parameters like temperature or pressure, water quality Attention: A device has to be sterile at the site of use (patient!). This means the product has to be wrapped before sterilisation! And sterilisation is going on despite wrapping! Wrapping in case of autoclavation: Steam has to pass the wrapping in both ways but no bacteria! 5 Sterilisation: Physical: Autoclave Saturated water steam 121 C, 2 bar, 15-20 minutes 134 C, 3 bar, 5 minutes CJD (prions): 18 minutes Hot air 200 C, 10 minutes 180 C, 30 minutes 160 C, 200 minutes Chemical: Ethylene oxide (50-60 C air!) Formaldehyde (70 C air!) Plasma (45 C Channels!) 6 3
Steam sterilisation Water steam is much more efficiant than dry heat of the same temperature: The energy content is bigger (1.000 times more energy is provided). Microorganisms swell and get more heat sensitive. Killing of Corynebacterium diphtheriae at 90 C Relative humidity Time 20 % 180 minutes 40 % 120 minutes 60 % 5 minutes 80 % 2 minutes 7 Minimal time for sterilisation Process Pressure, temperature time Steam sterilisation 1 bar, 120 C 20 minutes Steam sterilisation 2 bar, 134 C 5 minutes (RKI) Steam sterilisation 2 bar, 134 C 3 minutes (WHO) Steam sterilisation 2 bar, 134 C 3.5 minutes (EN 285) Dry heat sterilisation 180 C 30 minutes Dry heat sterilisation 160 C 200 minutes 8 4
Time to kill bacteria in dry air 120 C 140 C 160 C 180 C Staph. Aureus 30 minutes 15 minutes 8 minutes - E. Coli 30 minutes 10-15 minutes 8 minutes - Salmonella typhi 20 minutes 10 minutes 5 minutes - Anthrax spores 120 minutes 60 minutes 15-30 minutes 10 minutes Tetanus spores - 30 minutes 12 minutes 1 minutes Soil spores - - 30-90 minutes 15 minutes 9 Air content of water steam Time to kill (2 bar) 0 % 5 minutes 10 % 5 minutes 15 % 9 minutes 35 % 23 minutes 50 % 26 minutes 75 % 42 minutes 85 % 55 minutes 10 5
11 Sterile goods must be packed Container, mostly aluminium Paper plastics combination Sterilisation paper (Vlies) Do not wrap after sterilisation! 12 6
Classic container and vlies wrapping 13 14 7
Cleaning (left) and wrapping (right) without enough distance 15 16 Clean (sterilizer) and dirty (washer disinfector) work too close 8
Daily inspection of an autoclave Visual inspection (e.g. clean? Seal?) Empty charge (warming up) Bowie Dick test Vacuum test according to producer 17 Bowie Dick test 18 9
Testing and control of autoclaves Physical: Control of parameters (online registration of temperature and pressure). Thermologger. Chemical: Chemical indicator on charge. Biological: Biological indicator (spores): e.g. spores of Geobacillus stearothermophilus Every half year or 400 charges Use 5: 4 in autoclave, 1 as positive control 19 Some other chemical control system 20 10
Sterilisation other quality necessities Staff must be trained: Basic course. Repeated training. Documentation of training. Validation of sterilisation (reprocessing of medical devices): yearly Documentation: Temperature, pressure Unblock sterile products 21 22 11
23 Storage of sterile products Dry environment Own room (sterile air) or cupboard (closed storage) no shelfes (open storage) Time frame for usage: Open storage: within days Own room or cupboard: 6 months 24 12
Physical disinfection methods are better than chemical ones: Higher safety of disinfection! Burning of wound 25 Disinfection Disinfection of surfaces: Bucket with water and disinfection Floors (often only cleaning) Furniture (especially near to patient) Disinfection of medical devices: Used instruments: cleaning disinfection sterilisation Best of all washer disinfectors Second choice: manual disinfection Skin disinfection Operation, take blood Alcohol Hand disinfection Alcohol Mucous membranes disinfection 26 13
Disinfectants for surfaces and manual disinfection of medical devices Cold water, use dosing aid, gloves, protective goggles, do not mix with soap oder detergents! Better use a dosing unit Surfaces disinfection: Wipe Concentration and time Time usually not to be waited for Instrument disinfection: Different times and concentrations available Keep the respective time 27 Spraying only if wiping is not possible: Combine with wiping! 28 14
Viruses bacteria Bacteri a spores Chemical disinfectants and their usage moulds hands skin surface s Alcohols (+) + - + + + (+) + instrum ents Formal- + + (+) + - - + + + dehyde Glutaraldehyde + + (+) + - - + + Glyoxal + + - + - - + + Quats + (+) - + - - + + + PVPiodine + + (+) + (+) + - - - Chlorine + + (+) + (+) (+) (+) + Peracetic + + + + (+) + + acid phenol (+) + - + - - - - - clothes 29 Oxidants Reactive oxygen species: Hydrogen peroxide, ozone, peracetic acid and related substances. Hydrogen peroxide: no disinfectant not enough active against bacteria and viruses. Ozone: only water disinfection. Peracetic acid: disinfectant, also partly effective against spores Explosive, must be down concentrated, corrosive, concentration is diminishing i i with time Also new related substances available without toxic profile. 30 15
Other problems with disinfectants Protein mistake (looses effect after reaction with proteins): Aldehydes, peracetic acid, quats, chloramine Soap mistake (looses effect after reaction with soap/detergents): Iodine, quats, phenole, chloramine corrosive: Peracetic acid, chloramine Effect on plastics: Alcohol l may dissolve out phtalates t (plasticized i PVC) Alcohol may damage plexiglass Phenol and alcaline solvents may damage polyethylene, polypropylene, polyamide 31 32 16
Virus efficiacy Enveloped viruses: e.g. HIV, Hep. B, Hep. C, Influenza, Herpes, SARS Most disinfectants working, e.g. alcohol Not enveloped viruses: e.g. Norovirus, Rotavirus, Hep. A, Papilloma Virus, Polio Only aldehydes and oxygen producing substances 33 Chloramine Effective by setting free chlor (hypochlorite) Europe: Chloramine T = Tosylchloramidnatrium = 25 % Chlor available Efficiacy: Bacteria Viruses: > 2 % Polio: 1 %, 4 minutes Influenza: 0.5 %, 1 minute HBV: 1-2 %, 30 minutes 2 hours so not safe Spores: no Indications: Food production, animal farms, water disinfection But high protein mistake better use only on clean surfaces Hands: 1-2 % - but corrosive! Alcohol more efficiant 34 17
Hand disinfection Only alcoholic handrub > 70 % alcohol (in sum) better virus efficiacy i Dispenser with ellbow operating 30 seconds (hygienic hand disinfection) 3 minutes (surgical hand disinfection) 35 Scin disinfection Intracutan, subcutan, intramuscular, intravenous injections, take blood, intravenous canula for infusions Hygienic i hand disinfectioni (alcoholic) skin disinfectant spray, rub with pad Wait 15 seconds Injection site should be dry (pain!) Use non sterile single-use gloves for blood taking and i.v injections and i.v. canula (staff protection) 36 18
Skin disinfection Punction of joints, subarachnoid space, sterile body cavity > 1 minutes hand disinfection Sterile gloves, sterile gown, mask, hat Skin disinfectant, sterile pad At least wait 1 minutes, better 3-5 minutes 37 Skin disinfection before surgery Alcoholic skin disinfectant Sterile pads move from center to periphery use each pad only once skin must be moist all the time skin must be dry at the end Minimum 3 minutes Region with sweat glandes: 10 minutes Mucous membranes: iodine, octenidin, lavasept at least 3 minutes 38 19
Thanks 39 20