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1. STERILISATION AND
DISINFECTION

2. Objective :
To remove / destroy
the micro organisms
from materials / areas.

3. Sterilisation :
As the process by which
are articles, surface,
medium is free of all living
micro organisms either in
the vegetative form / spore
state.

4. Disinfection :
Means the destruction
/ removal of all
pathogenic organisms
capable of giving rise to
infection.

5. Antisepsis :
It’s defined as to
prevent the infection
usually by inhibiting the
growth of bacteria in
wounds / tissues.

6. Chemical disinfectants :
Which can be safely
applied to the skin / mucous
and are used to prevent
infection by inhibiting the
growth of bacteria.

7. Bactericidal agents :
Which are able to kill
the bacteria.

8. Bacteriostatic agents
:
Only present the
multiplication of bacteria
which may however
remain alive.

9. Decontamination :
The process of reentering
an article an article / area free
of danger from contaminants,
including microbial, chemical
radioactive and other
hazards.

10. Sterilisation
Physical Chemical

11. A.]Physical :
1.Sunlight
2.Drying
3.Dry heat –
-flaming
-Incenaration
- hot air

12. 4.Moist heat :
-Pasterisation
-steaming.
-Boiling
5.Filteration :
-candles
-Aspestos pads
-Membranes

13. 6.Radiation
7.Ultrasonic and sonic
vibrations

14. B.]Chemical :
1.Alcohol – Ethyl
-Isoprophyl
-Tricholoro butanol
2.Aldehydes –
Formaldehyde
-Glutaraldehyde

15. 3.Dyes
4.Halogens
5.Phenols
6.Surface active agents
7.Metalic salts

16. 8.Gases :
-Ethyleneoxide
-Formaldehyde
-Beta propioketone

17. 1.SUNLIGHT
Spontaneous sterilization
under natural condition –
Ultraviolet rays.
Bactericidal activity

18. Direct sunlight-Ultraviolet rays
Heat rays: Germicidal effect
Eg:Typhoid bacillus in sunlight-killed
in 2 hours
Controls in dark-alive after 6 days.
Bacteria suspected in water –
destroyed by exposure to sunlight.

19. 2.DRYING
-Unreliable method
Drying in air – spores are
unaffected.

20. HEAT:
-Reliable method
Factors influencing
sterilization by heat
-Nature of heat : Dry/Moist
-Temperature and time.
-Number of micro organisms
present.

21. Charateristics of the
organisms :
species, Strain, Sporing
capacity
Type of metrials from
which the organisms have
to be indicated.

22. Killing effect and dry
heat is due to protein
denaturation.

23. The time required to kill a
suspension of organisms at a
predetermined temperature in
a specified environment.
The time is related to the :
•The number of organism

24. •Presence / Absence of spores
•Strain and characteristic of the
organisms.
•The nature of material
•The presence a disinfectants, high
acid/alkaline PH.

25. 3.DRY HEAT
Flaming-
Inocculating loope/wire, the
tip of the forceps and spatules
are held in a Bunsen flame till
they become red hot.

26. Inoculation loops
carrying infective material
may be dipped in a
disinfectant before flaming
to prevent spattering.

27. Incineration-
This is an excellent method
for safely destroying
materials such as
contaminated cloths and
pathological materials.

28. Hot air oven-
This is the most widely used
method of sterilization by
heat.

29. A holding period of 160.C
for 1 hour is used to
sterilize glassware,
forceps.
Scissors, Scalpels, all –
glass syringes, swabs,
some pharmaceutical
products.

30. Such as liquid
paraffin, dust of heat
and its penetrating
power is low.

31. Cutting instruments
such as those used in
ophthalmic surgery,
should ideally be
sterilized for two hours at
150.C.

32. The British
Pharmacopoeia
recommends a holding
time of 1 hour at 150.C for
oils, glycerol and dusting
powder.

33. Sterilisation control:
The spores of
nontoxigenic strain of
Clostridium tetani are used
as a microbiological test of
heat efficiency.

34. 4.MOIST HEAT:
Temperature blow 100.C :
For pasteurization of milk –
Temperature employed is
either 63.C for 30minutes.
{Holder method}

35. or 72.C for 15-20secons.
Followed by cooling quickly to
13.C or lower.
By these processes all
nonsporing pathogens such as
mycobacteria, brucellae, and
salmonellae are destroyed.

36. Vaccines of nonsporing
bacteria are heat
inactivated in special
vaccine baths at 60.C for 1
hour.

37. A temperature of 80.C
for 5-10minutes destroys
the vegetative forms of all
bacteria, yeasts.
Most viruses inactivated
very rapidly at 60.C.

38. Temperature at 100.C:
[Boiling]: Vegetative bacteria
are killed almost immediately
at 90-100.C
But sporing bacteria require
prolonged periods of boiling.

39. Boiling is not
recommended for the
sterilization of instruments
used for surgical
procedures.

40. Steam at atmospheric pressure
[100.C] :
An atmosphere of free steam is
used to sterilize culture media.
Which may decompose if
subjected to higher temperature.

41. A single exposure of ninety
minutes usually ensures
sterilization but media containing
sugars or gelatin an exposure of
100.C for 20 minutes on three
successive days is used.

42. Steam under pressure:
The principle of the
autoclave or steam sterilizer is
that water boils when its
vapour pressure equals that of
the surrounding atmosphere.

43. Sterilisation by steam under
pressure is carried at
temperatures between 108.C
and 147.C.
By using the appropriate
temperature and time.

44. A variety of materials such as:
 Dressings
Instruments
Labortory ware
Media
Pharmaceutical products can
be strilised.
Aqueous solutions are strilised
between 108.C and 126.C.

45. Several types of steam sterilizers
are in use:
1.laboratory autoclaves.
2.hospital dressing sterilizers.
3.instrument strilsers
4.Rapid cooling sterilizers.

46. 5.FILTRATION:
Filtration helps to remove bacteria
from heat labile liquids such as sera
solutions of sugars or antibiotics
used for preparation of culture
media.
As viruses pass through ordinary
filters.

47. Filters can be used to obtain
bacteria – free filters of clinical
samples for virus isolation.
The following types of filters used:
1.Candle filters : used for
purification of water for industrial
and drinking purposes.

48. 2. Asbestos filters :
-Are disposable
-Single use discs

49. 3.Sintered glass filters:
Are prepared by heat

50. 4.Membrane filters:
-Made of cellulose esters.
-Used water purification and
analysis. sterilisation .
-For the preparations of
solutions of parenteral use.

51. 6.RADIATION:
Two types of radiation are
used for sterilization.
1.Non ionizing- Infra red and
ultraviolet rays
2.Ionising – gamma rays and
high energy electrons

52. 7.ULTRASONIC AND SONIC VIBRATION
Contain bactericidal powers
Microorganisms vary in their
sensitivity to them and
survivors have been found.

53. CHEMICAL AGENTS
Several chemical agents are
used as antiseptics and
disinfectants.
 Chemical agents act:
-Protein coagulation.
-Distruption of cell membrane.
-Enzymes diverts.

54. 1.ALCOHOLS
Ethyl alcohol and
isopropyl alcohol are the
most frequently used.
Used skin antiseptics

55. Denaturating bacterial
proteins.
They have no action on
spores.
To be effective they must be
used at a concentration of 60-
70% in water.

56. Iso propyl alcohol-
•better fat solvent
•More bactericidal
•Less volatile

57. •Used for clinical disinfection
of clinical thermometers.
Methyl alcohol-
•Effective against fungal
spores
•Used for treating
cabinets,incubators.

58. 2.ALDEHYDES
Bactericidal
Sporicidal
Has lethal effect on
viruses.

59. Formaldehyde :
Gas is used for sterilizing instruments.
-Heat sensitive catheters
-wards
-Sick rooms
-Laboratories
-Clothing
-Bedding
-Furniture
-Books
The gas is irritant and toxic when inhaled

60. Glutaraldehyde:
Similar to formaldehyde
Specially effective against
tubercle bacilli
Fungi
Viruses
Less toxic and irritant to the
eyes and skin.

61. 3.DYES
Two groups of dyes
1.Aniline dyes
2.acridine dyes

62. Used skin and wound
antiseptics.
Both are baceriostatic in
high dilution
Low bactericidal activity.

63. The aniline dyes in use
are:
1.brilliant green
2.Malachite green
3.Crystal violet
Active against gram
negative organisms.

64. No active against tubercle bacilli
Malachite green-Lowenstein
medium
-Non irritant and non toxic.
Acridine dyes - more active against
Gram positive organisms.
than gram negative organisms.

65. 4.HALOGENS
1.Iodine - aqueous and alcoholic
solution has been used widely as
skin disinfectant.
Bactericidal
Moderate action against spores
Active against tubercle bacteria
and viruses

66. 2.Chlorine and its compounds -
used as disinfectants for many
years.
Water supplies
Swimming pools
Food and dairy industries-
disinfection

67. 5.PHENOLS
Obtained by distillation of
coal tar between temperature
of 170.C and 270.C.
-Antiseptic
-Disinfectant.
-Toxic to humans

68. Phenol[carbolic acid]-
powerful microbicidal
substance.
Lysol,cresol-active against
of widerange of organisms.
Cholorophenols, choloroxy
phenols-less toxic and irritant.

69. Used in control of pyogenic
cocci in surgical and neonatal
units in hospitals.
Cholohexidine-nontoxic, skin
antiseptic, aqueous solutions
are used in the treatment of
wounds.

70. 6.GASES
1.Ethylene oxide :
Highly penetrating gas.
Highly inflammable
Has explosive tendancy.
It reacts with DNA and
RNA.

71. Use as a disinfectant
Potential toxicity to human
beings.
Include mutagenicity,
carcinogenicity.

72. Effective all types of
microorganisms including
viruses and spores.
Sterilize a glass,
metal,paper surfaces,plastic,
soil, some foods.

73. 2.Formaldehyde gas:
Fumigation of
operation theatres and
other rooms.

74. 3.Betapropiolactone:
Condensation product
of ketone and
formaldehyde.

75. Efficient for fumigating
purposes than
formaldehyde.
Capable of killing all
microorganisms.
Very active against
viruses.

76. 7.SURFACE ACTIVE AGENTS
Substances which are alter
energy relationship at
interfaces, producing a
reduction of surface or
interfacial tension are referred
to as surface active agents.

77. Used as wetting
agents
Detergents
Emulsifiers

78. Classified in 4 groups:
-Anionic
-Cationic
-Nonionic
-Amphoteric

79. Most important antibacterial
agents-cationic
Eg:acetyl trimethyl ammonium
bromide [catavlon/cetrimide]
Benzalkonium chloride
Most active at alkaline pH

80. 8.METALIC SALTS
Germicidal activity
Salt of heavy metals have
a greater action.
Mild antiseptic

81. Weak bactericidal
Limited fungicidal action
Eg: silver salts in aqueous
solution
Copper salts-fungicides

82. Testing of disinfectants:
Single reliable test
Determine efficiency of a
disinfectant activity.