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2. Sterilization is the process of killing or
removing all forms of microorganism and
their spores from preparation of articles.
#Spore is a reproductive structure that is
adapted for dispersal and surviving for
extended periods of time in unfavourable
condition.

3. Antiseptics – Inhibit growth, destroy germs &
Spores.
Bacteriocides – Kill Bacteria
Bacteriostatic agent – inhibit growth of
Bacteria.
Disinfectants – kill Bacteria & Infectious agent
from non living articles.
Fungicides – Kill Fungi.
Germicides – Kill Germs but not spores.
Mycocides – Kill molds.
Viricides – Kill Virus.

4. TYPES OF
STERILIZATION
Physical Chemica
l
Radiatio
n
Filtration Gaseous
Dry heat
EX- Hot air
oven
Flaming
Moist heat
EX- Autoclave
Boiling
EX-
Ethylene
Oxide
Formalde
hyde
Non-ionic
EX- UV
Rays,
Ionic
EX- Gamma
& X Rays.
Membrane
filter
Millipore
Filter
Seitz Filter
Formalde
hyde,
Beta-
propiolact
one

5. •Oven designed specially for this purpose which are
electrically heated and thermostatically controlled.
•During dry heat sterilization the microorganism
and bacterial spores are killed by Oxidation.
•Exposure at 160 C for 1 hour is required.
•Dry heat sterilization may be done by means of
direct flame ( flaming ) or by Hot air oven.

6. o The material to be sterilized is kept in the hot part
of Bunsen burner’s flame for a few seconds and the
process is repeated several times.
o This method is generally used for those articles
which are used immediately.
EX- forceps, needles, knives, blades, scalpels, metal
spatulas, the mouth of culture tubes and bottles,
platinum loops.
o The method is not reliable for sterilizing greasy or
oily materials.

7. Hot Air Oven
 Hot air oven is suitable
for heat sterilization of
dry material like
Powder, metal devices,
glassware & other such
laboratory stocks.
 Dry heat destroy
microorganism by
dehydration & Oxidation
or even incineration.
Temperature C Time
140 C 3 hour
180 C 2 hour
260 C 45 minutes
There is two types of ovens-
 In which air is circulated by
gravity in all parts of chamber,
 Mechanical convection type
, in which air circulated by fan.

8. Precautions
Glass wares should be dry.
Oven should not over loaded.
The door of the oven should be opened when
necessary.
Applications
Glass wares sterilized by dry heat
Other equipment such as mortar & pestles, metal
ware like oinment tubes, dishes of stainless steel.
Powders.

9. Disadvantages
1 It required very long time heating, high temperature &
long exposure time.
2 Most medicament, rubber & plastic articles are
thermolabile get destroyed by this method.
3 Preparation containing water, alcohol or other volatile
substance can’t be sterilized

10. Also known as Steam Sterilization.
It is done by an Autoclave but on small scale a
pressure cooker can be used, in which Steam under
pressure is used.
By this method the microorganisms are destroyed by
denaturation and coagulation of some of the
essential proteins present in the microorganism.
Moist heat more powerful than Dry heat because-
The penetrating power of steam is much more
The thermal capacity of steam is much more than
that of Dry heat.

11. Autoclave
Autoclave work on the
principle of Saturated
Steam under pressure
in which increase the
pressure, rise the boiling
point and produce
steam with high
temperature.
In this process most of
microorganism are
killed at a temp. 121 C,
Steam pressure 15 PSI
and holding time 15
minutes.
Pressure(PSI) Temperature
C
Time
10 PSI 115.5 C 30
15 PSI 121.5 C 20
20 PSI 126.5 C 15
Autoclave consist
of cylindrical or
rectangular
chamber, water
heating system or
steam generating
system.
Steam outlet &
inlet valve and
temperature
pressure gauges.

12.  Some of the glassware and closures having
rubber parts are sterilized in autoclave.
 Nearly all the injection solutions & suspensions like
adrenaline, propanalol, atropine sulphate etc are
sterilized by autoclave.
 Variety of materials used in surgery like bandages,
caps, mask, towel, trolley clothes, hand gloves etc
are sterilized in autoclave.

13. Pasteurization process are used to make milk
safe and improve its keeping qualities.
The original method was developed by Louis
pasture to prevent the souring of wine.
Tyndallization
This technique was developed by
bacteriologist Tyndall.
This method of sterilization is used for
the spore forming microorganism

14. 3 Solutions packed in sealed containers, as ampoules,
are readily sterilized by this method.
4 Bulk solutions, glassware, surgical dressings, rubber
gloves and surgical instruments are effectively
sterilized by this method.

15. Precautions
The level of water in the autoclave should be
checked before operating.
The water level should be above the heating rod
or wire.
The heat sensitive materials should not be
sterilized by autoclave.

16. Chemical agents:
Action of chemical agents:
Protein Coagulation.
Disruption of cell membrane
resulting in exposure, damage/loss of
contents.
Removal of sulfhydryl group
essential for normol functioning of
enzyme.
Substate competition.

18.  Formaldehyde is the simplest compound in aldehyde
series.
 Formaldehyde is effective against bactericidal agent & kill
all bacteria including spores.
 Also used as an alcoholic solution for disinfection of
instruments.
Advantages
 Used for sterilization of certain instrument.
 Formaldehyde in gaseous form can be used for
disinfection.

19. At room temperature it is colorless gas.
Concentration used for sterilization range from 200-
1000 mg/litre.
Mode of Action – Responsible for the alkylation of
nucleic acid & proteins.
Advantages
Suitable for thermolabile substance.
Pre-packed articles can be sterilized because of the great
penetrating power of ethylene oxide.
Disadvantages
Long exposure is necessary & highly inflammable.
Toxic effect on Human being, It is carcinogenic.

20. Sterilization by radiation also known as Cold
sterilization because no heat is used in this
method.
Electromagnetic waves which include infra-red
radiation, ultra violet light, X-ray & gamma
rays.
These are two types-
Non-ionizing radiation
Ionizing radiation

21. Infra-red – Used for rapid mass sterilization of
prepacked items such as syringes.
U.V. rays – UV rays of shorter wave lengths are
more destructive than rays of longer wave lengths.
Used for sterilization of aseptic rooms or area where
the pharmaceutical processing carried out, for this
purpose the lamps may be fitted at the top of the
surface to be srerilized.

22. Disadvantages
Because of high cost involved all the industries can
not afford to install the plant
UV rays can damage eyes and are known to cause sun
burns & skin cancer in humans.

23. They are powerful radiation and very useful for
sterilization
Gamma Rays – Gamma rays are generally obtained
from radio-active isotopes of cobalt 60.
They kill microorganisms by ionization of atoms of
essential substance present in living
microorganisms.
Gamma rays are similar to X-rays of short wave
length. Being electromagnetic radiation both of
them have high penetration power, the fact which is
used in sterilization.

24. Disadvantages
> They lead to change in colour, solubility and texture of
the preparation.
> They also lead to decomposition of certain
medicaments.
> These radiations are harmful to the persons engaged
in this work so they must by protected and kept under
constant attention.