Helpful to learn about the sterilization process.

1. Bsc nursing
Microbiology
Unit:- 3 sterilization
BY:- PRAGYA TIWARI

2. Sterilization:-
The process of killing or removing bacteria and all other forms of living
microorganism and their spore from preparation
Term disinfection and sterilization causally interchange.
Use of sterilization:-
1.In food and drug industry.
2.Surgical instruments etc need sterilization.
3.For bacteriological work, culture media container in laboratory.

3. Classification of sterilization :-

4. Classification:-
1. Physical agents
 Sunlight :- bacterial cell is filled with 4/5 of the weight with water. Moisture is essential for
the growth of bacteria.
Bacteriocidal Efrect due to the uv rays, heat rays. Large reservoir of water are naturally steriled by
it ie. River, pound ect.
Drying :- it shows deleterious (harmful) effect on many bacteria this method however is
unreliable.It is only theoretical intereste. Spores are unaffected by dying 4/5 of the bacterial cell
consist of water.
Spore are unaffected. Deleterious effect on many bacteria.
Heat :- heat is most reliable sterilization method it should be the method of choice unless it is
contraindicated. It is the method of choice or heat resistance. The substance or articles that may be
damaged by heat can be sterilised at lower temp. For linger period or by repeated cycle.

5. Heat is used in two forms :-
1. Drying heat
2. Moist heat
Dying heat :- dryheat has low power of penetration. The distraction effect of dry heat on bacteria due
to coagulation of cell protein.
Like :- flaming, incineration, hot air etc.
Moist heat :- temp. Below 100° c
Like :- pasteurization, (below 100°c), boiling and steam, under pressure.
Temp. Above 100°c is called steam under pressure.
Autoclave :- it is the process of sterilization by saturated steam under pressure above 100° . Steam
sterilization is carried out in a pressure chamber called an autoclave.

6. Many autoclave are used to sterilized equipment mad supplies by subjetive them to pressurized saturation steam
at 121°c for around 15-20 min depending on size of the load inter content.
Procedure:-
Water:- sufficient water put in cylinder.
Lid :- the lid is screwed tight with the discharge lap open and the safety valve is adjusted to the required pressure.
pressure.
Air removal :- the steam air mixture is allowed to escape freely till all the air has been displaced.
The discharge tap is now closed
Holding period:- the steam pressure raise inside and when it raach the desire set level, the safety valve open and
and the excess steam escape, from this point, the holding period is calculated.
Autoclave cooling :- when the holding period is over, the heater is turned off and the autoclave allowed to cool
cool
Air entry in autoclave:- thr discharge tap open slowly and air is allowed to enters the autoclave.

7. Removal of article :- the lid is now
opend, the sterilized articles remove.
 Uses:-
1. The sterilising culture media and
other lab. Supplies, rubber material,
dressing material.
2. For all material that are water
containing permeable or Wetable
and not liable to damage by the
process.

8. Filtration:-
It is a principle method used in the lab. For sterilization of heat labile material eg:-
cera, solution of sugar, antibiotics used for preparation of culture media.
Uses:-
 For sterilization of ophthalmic solutions, culture media, oil, antibiotics etc.
 For separation of bacteriophage and bacterial toxin from bacteria.

9. Chemical agents :-
 Alcohol :- the commonly used alcohol are ethyl alcohol, Isopropyl alcohol.
They must be used a conc. Of 60-70%in water to be affective, they are most
frequently used disinfectants and at by denaturation bacteria.
 Aldehydes:- Most aldehyde are used as disinfectants formulation along or in
combination. It is used for as aqueous and gaseous form. Formaldehyde gas is
widely used to sterilization.
 Phenol:- it is 1% bacteriocidal action. Phenolies an Protoplasmic poison at higher
conc. But at lower conc. Inactivated cellular enzymes system.

10. Chemotherapy:-
he treatment of disease with chemical substance is known as chemotherapy. The chemical
substance used in chemotherapy is called as Chemitheraputic agent.
Chemotherapy have been practice to reduce the no. Of microbes. Kr
inhibites their growth at conc. Low enough to avoid Undisarable damage to the host. Most of the
Chemitheraputic agents are antibiotics microbial product or their derivatives that can kill Suspetible
microorganism or inhibit their growth are called antibiotics.
 Chemotheraputic agent:- they are the chemical substance used to kill or inhibit the growth of
microorganism already Stablished tissue of body now-a-day the term antibiotics is used loosely
to describe agent used to treat systemic infection.
 Antimicrobial agent:- it would be more meaning to used term antimicrobial agent to designate
synthetic as well as naturally obtained durga that attenuated microorganism.

11.  Antiseptic and disinfectants :-
Antimicrobial substance that
are too toxic other than the topical
therapy and environment
decontamination are referred as
antiseptic or disinfectants

12. Classification of antimicrobial drugs :-
Several ways to classify antimicrobial drugs
 According to chemical structure :- sulfonamide, penicillin, tetracycline, polypeptide,
Cephalosporin.
 According to machenism of action :- inhibiting protein synthesis, inhibiting cell wall synthesis
etc.
 According to organism against which effect that antibacteria, antifungal, antiprotozol etc.
 According to spectrum
 According to type of action:- bacteriostatic, bacteriocidal
 According to source :- bacteria, fungi, Actinomyctes etc.