Download Sterilization

Physical
methods
Heat
Moist
Heat
Radiation
Dry
Heat
Ionized
radiati
on ,e.g.
X-ray,
Gamma
Ray
Nonionized
radiation,
e.g. UV
Heat
Moist heat
Autoclave
Boiling water,
Hot water,
Pasteurization
Dry heat
Incineration
Sterilization Disinfection
Sterilization
Dry oven
Sterilization
is used to sterilize
biohazardous trash and heatstable objects.
METHODS OF MOIST HEAT
the most commonly used
method of moist heat.
.
This method can kill all
kind of microorganisms including
vegetative forms and spore forming
m.o. like Clostridium spp., Bacillus spp.
and viruses.
cannot used to sterilize
heat sensitive media, heat sensitive
plastics and substance that repel
moisture like waxes, oils, powders. Care
is needed during this process in
addition to experience and skill.
Required special instrument for the
sterilization.
Intermittent
sterilization on 3 days intervals passing a
steam of hot air on the material for 30-60
min this cycle will repeated for 3 days.
Substance that can't withstand the
high temperature of the autoclave.

only used for sensitive
culture media, i.e. Those containing sera
or eggs.
this method can't kill the
spores, long time is required for complete
sterilization so it is not practical.
A simple boiling water
chamber is used.
Used mostly for drinking water,
food preparation and bedding.
It is a relied process for
disinfection not for sterilization because
it will kill most m.o but not the sporeforming bacteria.
can't kill heat resistant
bacteria, sporforming microorganisms,
the materials easily recontaminated
when removed from the water.
METHODS OF MOIST HEAT
is a technique in which
heat is applied to liquid to kill potential
agent of infection and spoilage, while at
the same time retaining the liquid's flavor
and food value.
to prevent transmission of milk –
borne bacteria from transmission from caw
to human like Brucella .milk after regular
Pasteurization is not sterile completely.
It longing the storage time of
milk, use to stop fermentation by some
winners.
not
kill
sporforming
bacteria, or some heat resistant viruses.
it is not commonly
used
as
moist
heat;
the
temperature used mostly is higher
than those used for moist
sterilization.
Kill by
dehydration that cause irreversible
denaturation of an essential enzymes.


1most commonly used to sterilize
the inoculating loop and needles using Bunsen
burner in microbiology labs.
in hospital and research labs for complete
destruction and disposal of infectious materials such
as syringes ---etc.
help to get rid of large amount of
contaminated materials at once. Fast and effective
but also limited to metals and heat resistant glass
materials.
Toxic air emissions and the presence
of heavy metals in ash have limited the use of
incineration, this method represents hazards to
operator (open flame) and to the environment
(contaminants on needle or loop often spatter when
placed in flame).
sterilization.
another mean of dry
used in labs and clinics
with heat resistant items that don't sterilize
well in moist heat substances like glassware,
metallic instruments, powders and oil (that
do not penetrated by steam).

this method is not suitable
for plastic , cotton ,papers which will burn
at high temperature, or for liquids which
will evaporate ,also this method requires
longer exposure times, and higher
temperatures than moist heat.
COLD
STERILIZATION
the principle effect of this method is to slow
the growth of culture and microbes in food
during storage. This method would kill some
m.o. but not kill staphylococcus spp.,
Clostridium spp., Bacillus endospores. This
method include: chilling, freezing,
desiccation, all of which is not considered as
sterilization method because it have erratic
effect as well as their killing effect is
uncertain.
omitted energy can be used as
an antibiotic agent,
 Can be divided into ionized radiation and
non-ionized radiation the most important
used radiation is gamma rays, X-ray,
Ultraviolet Ray (UV).
When a cell is bombarded by a certain waves its
molecules absorb the energy leading to one of
two consequences :
(1) Ionization radiation directly affect the microbe
DNA which would undergo mutations which
lead to chemical changes in the m.o. organelles
and production of toxic substances. Gamma
rays, X-ray are both ionization radiation.
(2) in case of non ionization radiation _UV_ high
energy waves that effect the molecules without
causing them to be ionized also leading to
formation of abnormal bond in the DNA and
thus become a source of mutations.

food sterilization
can penetrate liquids ,most of solid materials ,
sterilizing disposables such as plastic syringes,
catheters, or gloves before use, the most
commonly used are gamma radiation.
heat sensitive materials, can kill
not only bacteria but also insects, worms, fast,
high penetration power.
potential dangers to radiation
machine operators from exposure to radiation
and possible damage to some materials.
the
most common application of UV is by the UV light
lamp called germicidal lamp it is disinfectant
rather than steralint. Used to sterilize the air in
surgery room, microbiological labs,
slaughterhouses….etc. sterilization of drinking
water, for sterilization of vaccins and plasma,
walls, floors, meat, drugs, grafting tissue.
simple, not expensive, easy to
operate, not need heat, can kill fungal cells,
parasites, viruses, bacterial vegitativecells in
addition to spores.
poor penetrating power
through solid such as glass, even paper.UVhas a
damaging effect on human tissues, including
sunburn, retinal damages, cancer …etc.
(UV) TREATMENT SYSTEM FOR THE DISINFECTION
WATER.
OF
it is an effective method to remove microbes from
air and liquids.
Filtration of liquids is
accomplished by pulling the solution through a cellulose
acetate or cellulose nitrate membrane with a vacuum.
In practice, a fluid is strained through a filter' openings
large enough for the fluid to pass through small for
microorganisms to pass through. Most modern
microbiological filters are thin membranes whose pore
size can be carefully controlled and standardized.
FILTRATION
FILTRATION
is
the
method
of
choice for antibiotic solutions, toxic chemicals,
radioisotopes,
vaccines,
IV
fluids,
water
purification, milk…etc. which are all heatsensitive. Even air sterilization in some closed
environment (sterile room).
have no toxic effect on the material
that sterilized , and not subjected to heat that
might change its chemical nature, no harmful
effect on the environment, no hazard to the
operator.
cannot
remove
soluble
molecules (toxins) that can cause disease.
:


The use of chemical materials in sterilization, there
are 10000 chemical that has been use in sterilization in
homes, lab, hospitals …etc.
in every aspect of life like food preservations,
labs, surgery floors walls, as detergents used for
sterilizing heat-sensitive objects.
The most common chemical sterilant is
used for sterilizing heat-sensitive objects. Fast, easy to
find , some of the chemicals can kill all kind of
microorganisms.
Wide range of side effect, some of
them are toxic to humans, can be abused by people,
there is no perfect chemical that fulfill all the
requirements of a safe effective agent.
the most common used
methods for both detection of
microorganisms' directly in clinical
specimens and for characterization
of organisms grown in culture.
 There
are four types of microscopy:
The most
commonly used microscopy in ordinarily labs; allow
observing the dead m.o. need many kind of stain like gram
stain.
This method is
not commonly used in diagnostic
microbiology only used to identify the
medically important fungi that grown in
culture. It allows seeing the viable m.o. as
well as the dead one.
Similar to phase
contrast microscopy in that it use microscopic
technique rather than the use of dies it use to
detect spirochetes because it is difficult to
grown in culture.
The m.o. in the
specimen are stained with fluorescent
dye , on exposure to excitation light , m.o
are visually detected by the emission of
fluorescent light by the dye with they
have been stained.
This kind of
microscopy is using light rather than
the dye to visualize the small objects,
(like T.V.) 3 Dimensional pictures