Sterilisation and disinfection

PPT on sterlisation and disinfection

1. STERILIZATION
AND
DISINFECTION

3. Microorganisms are the agents of contamination,
infection, and decay.
Hence it becomes necessary to remove them
from materials and areas.
Early civilization practiced salting, smoking,
pickling and exposure to sunlight .

4. STERILIZATION
Process by which all living
microorganisms , including viable spores,
are either destroyed or removed from an
article ,body surface or medium.

5. DISINFECTION:
Reducing the number of pathogenic
microorganismsto the point where they
no longer cause diseases.
Process that destroys or removes most if
not all pathogenic organism but not bacterial
spores.

6. Sepsis: Comes from Greek for decay or putrid.
Indicates bacterial contamination.
Asepsis: Absence of significant contamination.
Aseptic techniquesare used to prevent
contamination of surgical instruments, medical
personnel, and the patient during surgery.

7. BacteriostaticAgent:
An agent that inhibitsthe growth of bacteria, but
does not necessarily kill them.
Bactericidal Agent:
An agent that kills bacteria. Most do not kill
Endospores.
SporicidalAgent:
An agent that kills spores.

8. Methods of Sterilisation
Physical
methods
Drying
Heat
Dry heat
Flaming
Incineration
Hot Air Oven
Moist heat
Temp. below 100˚c e.g
pasteurisation, water bath
and inspissation.
Temp. at100˚c e.g. boiling,
steaming and tyndallisation
Temp. above100˚c e.g.
Autoclave

9. Methods of Sterilisation
contd..
Filtration : depth filters and membrane filters
Radiation:
Ionizing radiation : ¥ rays, X-rays and cosmic
rays
Nonionizing radiation: ultraviolet (UV) and
Infrared rays
Ultrasonic Vibration

10. FLAMING
Inoculation loop or
Wire, the tip of
Forceps and
spatulas are held in
a bunsen flame till
they are red hot.

11. INCINERATION
Thisisanexcellent
methodofdestroying
materialssuchas
contaminatedcloth,
animal carcasses
and pathological
materials.

12. Physical Methods of Sterilisation
Sterilisation By Dry Heat:
Hot Air Oven
•Kills by oxidation effects
•The oven utilizes dry heatto
sterilize articles
•Operated between 50
o
C to
250/300
o
C.
•A holding period of 160
o
C for 1 hr
is desirable.
•There is a thermostatcontrolling
the temperature.
•Double walled insulation keeps
the heat in and conserves energy,

13. Uses:
To steriliseForceps, Scissors, Scalpels, Swabs.
Glasswares, petridishes, flasks, pipettes and test tubes.
Pharmaceuticals products like Liquid paraffin, dusting
powder, fats and grease.

14. Kills microorganisms bycoagulatingtheir proteins.
MOIST HEAT STERILISATION IS CARRIED OUT WITH
FOLLOWING METHODS
Temp below 100
o
C: “Pasteurisation”, Inspissator.
Temperature at 100
o
C: Boiling.
Steam at atmospheric pressure: Koch/Arnold’s
steamer.
Steam under pressure: Autoclave.
MOIST HEAT STERILIZATION

15. Pasteurisation
Process of killing of pathogens in the milk but
does not sterilize it .
Milk is heated at 63
o
C for 30 mins.
(HOLDER METHOD)
At 72
o
C for 15-20 Sec. Rapid cooling to 13
o
C
(FLASH PROCESS)

16. HOT WATER BATH
To inactivate non
sporingbacteria for the
preparation of vaccines
-Special vaccinebath
at 60
o
Cfor one hour is
used
Serum or body fluids
containing coagulable
proteins can be
sterilized by heating for
1 hr at 56
o
C in a water
bath for several
successive days.
Water Bath

17. INSPISSATOR
Sterilizes by heating at 80-85
o
C for half an
hour for 3 successive days
Used to sterilize media such as Lowenstein-
Jensen & Loefller’s serum
Inspissator

18. TEMPERATURE AT 100
O
C
Boiling:
Kills vegetative forms of bacterial pathogens.
Hepatitis virus: Can survive up to 30 minutes
of boiling.
Endospores: Can survive up to 20 hours or
more of boiling

19. STEAM AT ATMOSPHERIC
PRESSURE
Steamisgenerated
usingasteamer
(Koch/Arnold)
ConsistsofaTin
cabinet
Hasaconicallidto
enablethedrainage
ofcondensedsteam
Perforatedtrayabove
ensuresmaterialsare
surroundedbysteam.
For routine
sterilizationexposure
of90minsisused Steam Sterilizer

20. For media containing sugar and gelatin
exposure of 100
o
C for 20 min for 3 successive
days is used
The process is termed as Tyndallisation
/Intermittent Sterilization

21. STEAM UNDER PRESSURE -
AUTOCLAVE
Works on the principle of Steam
under pressure
Autoclave consists of a vertical or a
horizontal cylinder.
One end has an opening which is
meant for keeping materials to be
sterilised.
The lid is provided with a Pressure
gauge, to measure the pressure
A safety valve is present to permit
the escape of steam from the
chamber
Articles to be sterilisedare placed
in the basket provided
Sterilisationis carried out under
pressure at 121ºfor 15 mnts.
AUTOCLAVE

22. Sterilisation by filtration
Filtration helps to remove bacteria from heat
labile liquids such as sera and solutions of
sugar, Antibiotics.
The following filters are used
Candle filters
Asbestos filters
Sintered glass filter
Membrane filters

23. CANDLE FILTERS
Widely used for
purification of water
Two types
(a) Unglazed ceramic filter
–Chamberland filter
(b) Diatomaceous earth
filters –Berkefeld filter

24. ASBESTOS FILTER
Disposable single
use discs
High adsorbing
tendency
Carcinogenic
Eg: Seitz filter
SEITZ FILTER
ASBESTOS DISCS

25. MEMBRANE FILTERS
Made of cellulose esters
or other polymers
Uses
Water purification &
analysis
Sterilization & sterility
testing
Preparation of solutions
for parenteral use

26. RADIATION
Non-Ionisingradiation
Used in rapid mass sterilisationof prepackedSyringes
and catheters
For disinfection of operation theaters, laminar flow hoods
and water treatment.
IONISING RADIATIONS
X-rays, gamma rays & cosmic rays.
No appreciable increase in the temperature –COLD
STERILISATION
Steriliseplastics Syringes, catheters, grease fabrics
metal foils

27. CHEMICAL METHODS
Chemical agents
act by
Protein coagulation
Disruption of the
cell membrane
Removal of
Sulphydrylgroups
Substrate
competition

28. CHEMICAL METHODS
Alcohols: Ethyl alcohol, isopropyl alcohol
Aldehydes: Formaldehyde, Glutaraldehyde, Ortho-
phthaaldehyde
Phenolic compounds : Cresol, Lysol, Chlorohexidine,
Chloroxylenol, Hexachlorophene
Halogens: chlorine , Iodine, Iodophors
Oxidizing Agents :hydrogen peroxide, Peracetic acid
Salts: Mercuric chloride, copper salts
Surface active agents: Quaternary ammonium compounds
and soaps
Dyes: Aniline dyes and Acridine dyes
Gas Sterilization : Ethylene oxide, Betapropiolactone,
Plasma sterilization, Low temp. steam formaldehyde

29. ALCOHOLS
Ethanol /Isopropyl alcohol are frequently used
No action on spores
Concentration recommended 60-90% in water
Uses
Disinfection of clinical thermometer.
Disinfection of the skin –Venupuncture

30. ALDEHYDES
Formaldehyde & Glutaraldehyde are
frequently used
Formaldehyde is bactericidal, sporicidal & has
a lethal effect on viruses.
Glutaraldehyde is effective against Tubercle
bacilli, fungi and viruses

31. USES
FORMALDEHYDE
To preserve anatomical specimens
Destroying Anthrax spores in hair and wool
10% Formalin+0.5% Sodium tetra borate is
used to sterilisemetal instruments
GLUTARALDEHYDE
Used to treat corrugated rubber anesthetic
tubes, Face masks, Plastic endotrachealtubes,
Metal instruments and polythene tubing

32. PHENOLS
Eg:Lysol,cresol
Obtainedbydistillationofcoaltar
Phenolsarepowerfulmicrobicidalsubstances
Phenolicderivativeshavebeenwidelyusedas
disinfectantsforvariouspurposesinhospitals
Variouscombinationsareusedinthecontrolof
pyogeniccocciinsurgical&neonatalunitsin
hospitals.
Aqueoussolutionsareusedintreatmentof
wounds

33. HALOGENS
Iodine
Iodinein aqueous and alcoholic solution has been
used widely as a skin antiseptic and kills
microorganisms by oxidizing cell constituents and
iodinating cell proteins.
Actively bactericidal with moderate against
spores
Tincture of iodine: 2 % iodine in water ethanol
solution of potassium iodide.
Iodophor: prepared by complexingiodine with an
organic matter such as povidone
some brand names are Wescodyneand Betadine

34. HALOGENS
Chlorine
Chlorineand its compounds have been used
as disinfectants in water supplies , swimming
pools,asa laboratory disinfectant and as
bleaching agent.
It may be available as
1.Chlorine gas
2.Sodium Hypochlorite (1-5 %)
3.Calcium Hypochlorite

35. SURFACE ACTIVE AGENTS
Substances which reduce the surface tension –
Surface active agents
Cations are widely used in the form of
quaternary ammonium compounds.
Cetavlon or cetrimide
Markedly bactericidal, active against Gram
positive organisms.
No action on spores, tubercle bacilli, viruses

36. METALLIC SALTS
The salts of silver, copper, arsenic, zinc and
mercuryare used as disinfectants.
Act by coagulating proteins
Marked bacteriostatic, weak bactericidal and
limited fungicidal activity
Silver sulfadiazine is used on burn surfaces.
Silver nitrate (1%), copper sulphate

37. DYES
ANILINE DYES
Are Brilliant green, Malachite green & Crystal
violet
Active against Gram positive bacteria
No activity against tubercle bacilli

38. DYES
ACRIDINE DYES
Acridine dyes in use are orange in colour
Effective against Gram positive than Gram
negative
Important dyes are Proflavine,
Acriflavine,Euflavine

39. GASES
Ethylene Oxide
Colourless,Highly penetrating
gas with a sweet ethereal
smell.
Effectiveagainstalltypesof
microorganismsincludingviruses
andsporesSpeciallyusedfor
sterilisingheart-lungmachines,
respirators,sutures,dental
equipments,booksandclothing.
AlsousedtosteriliseGlass,metal
andpapersurfaces,plastics,
oil,somefoodsandtobacco.

40. FORMALDEHYDE GAS
Widely employed for fumigation of operation
theatres and other rooms
Formaldehyde gas is generated by adding 150
g of KMnO4 to 280 ml of formalin for every
1000 cu. Feet of room volume.
The room is sealed for 48 hrs.
The gas is irritant and toxic so no longer
preferred, and is replaced by modern methods
of fumigation.
Ecoshield ,bacillocid and virkon.

41. BETA PROPIOLACTONE
Used in fumigation
For sterilisation 0.2% BPL is used
Has a rapid biocidal activity
Very effective against viruses

42. THANK YOU