1

Disinfection and sterilisation

Mongolia2011

Prof Dr Walter Popp

1

Prof. Dr. Walter PoppHospital Hygiene, University Clinics Essen, Germany

Term Definition Reduction factor of germs

Cleaning Remove dirt including microorganisms (no need to kill them) by mechanicla

10 - 100

) ymeans.

Mostly wiping with water (and detergents).

Sometimes vacuum or high-pressure water blaster.

disinfection Reduction of number of pathogenic microorganisms so that they are not enough to cause an infection

1.000 – 100.000

2

to cause an infection.

Sterilisation Killing all bacteria (including spores), mould/fungi, inactivation of all viruses.

Every sterile product has to

be sterile!

2

3

Sterility

Definition:Sterile means that a product is free of bacteria, their spores, mould/fungi, viruses must be inactivated, also prions.

But: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 106 (= 1 Million) sterilised products.

4

3

Sterility

Testing a new sterilisation process:It is impossible to test 106 products.Therefore testing with bacteria which are hard to sterilise, measuring physical parameters like temperature or pressure water qualityparameters 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 steam121°C, 2 bar, 15-20 minutes134°C, 3 bar, 5 minutes

CJD (prions): 18 minutesHot air

200°C, 10 minutes180°C, 30 minutes160°C, 200 minutes

6

Chemical:Ethylene oxide (50-60°C – air!)Formaldehyde (70°C – air!)Plasma (45°C – Channels!)

4

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.g g

Killing of Corynebacterium diphtheriae at 90°C

Relative humidity Time

20 % 180 minutes

40 % 120 minutes

60 % 5 minutes

7

60 % 5 minutes

80 % 2 minutes

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

8

y

Dry heat sterilisation 160°C 200 minutes

5

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

9

Tetanus spores

- 30 minutes 12 minutes 1 minutes

Soil spores - - 30-90 minutes 15 minutes

Air content of water steam Time to kill (2 bar)

0 % 5 minutes

10 % 5 minutes10 % 5 minutes

15 % 9 minutes

35 % 23 minutes

50 % 26 minutes

75 % 42 i t

10

75 % 42 minutes

85 % 55 minutes

6

11

Sterile goods must be packed

Container, mostly aluminium

Paper plastics combination

12

Sterilisation paper (Vlies)

Do not wrap after sterilisation!

7

13Classic container and vlies wrapping

14

8

15Cleaning (left) and wrapping (right)

without enough distance

16Clean (sterilizer) and dirty (washer

disinfector) work too close

9

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

10

Testing and control of autoclaves

Physical:

Control of parameters (online registration of temperature and pressure).p )

Thermologger.

Chemical:

Chemical indicator on charge.

19

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

20

Some other chemical control system

11

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 …

21

p , p

Unblock sterile products

22

12

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

13

Physical disinfection methods are better than chemical ones:Higher safety of disinfection!

25

Burning of wound

Disinfection

Disinfection of surfaces:Bucket with water and disinfectionFloors (often only cleaning)Furniture (especially near to patient)

Disinfection of medical devices:Used instruments: cleaning – disinfection – sterilisationBest of all washer disinfectorsSecond choice: manual disinfection

Skin disinfectionOperation, take blood …Alcohol

26

Alcohol

Hand disinfectionAlcohol

Mucous membranes disinfection

14

Disinfectants for surfaces and manual disinfection of medical devices

Cold water, use dosing aid, gloves, protective goggles, do not mix with soap oder detergents!p g

Better use a dosing unit

Surfaces disinfection:

Wipe

Concentration and time

Time usually not to be waited for

27

Instrument disinfection:

Different times and concentrations available

Keep the respective time

Spraying only if wiping is not possible:Combine with wiping!

28

15

Chemical disinfectants and their usage

Viruses bacteria Bacteria spores

moulds hands skin surfaces

instruments

clothes

Alcohols (+) + - + + + (+) +

Formal- + + (+) + - - + + +Formaldehyde

( )

Glutaral-dehyde

+ + (+) + - - + +

Glyoxal + + - + - - + +

Quats + (+) - + - - + + +

PVP-iodine

+ + (+) + (+) + - - -

Chl i ( ) ( ) ( ) ( )

29

Chlorine + + (+) + (+) (+) (+) +

Perace-tic acid

+ + + + (+) + +

phenol (+) + - + - - - - -

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 di i i hi ith ti

30

diminishing with time

Also new related substances available without toxic profile.

16

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:Al h l di l t ht l t ( l ti i d PVC)

31

Alcohol may dissolve out phtalates (plasticized PVC)Alcohol may damage plexiglassPhenol and alcaline solvents may damage polyethylene, polypropylene, polyamide

32

17

Virus efficiacy

Enveloped viruses:e.g. HIV, Hep. B, Hep. C, Influenza, Herpes, SARSMost disinfectants working, e.g. alcohol

Not enveloped viruses:e.g. Norovirus, Rotavirus, Hep. A, Papilloma Virus, PolioOnly aldehydes and oxygen producing substances

33

Chloramine

Effective by setting free chlor (hypochlorite)

Europe: Chloramine T = Tosylchloramidnatrium = 25 % Chlor available

Efficiacy:Efficiacy:BacteriaViruses: > 2 %

Polio: 1 %, 4 minutesInfluenza: 0.5 %, 1 minuteHBV: 1-2 %, 30 minutes – 2 hours – so not safe

Spores: no

Indications: Food production, animal farms, water disinfection

34

But high protein mistake – better use only on clean surfacesHands: 1-2 % - but corrosive! Alcohol more efficiant

18

Hand disinfection

Only alcoholic handrub

> 70 % alcohol (in sum) – better virus ffi iefficiacy

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

H i i h d di i f tiHygienic hand disinfection

(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

injections and i.v. canula (staff protection)

19

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 ydry at the end

Minimum 3 minutes

Region with sweat glandes: 10 minutes

Mucous membranes: iodine, octenidin, lavasept – at least 3 minutes

38

20

Thanks

39