1.
Sterilization
Assistant Professor
Mr. Swapnil Shankar Patil
(M. Pharm, PhD-Research
Scholar)
Department of Pharmaceutics

2.
Sterilization
 It is the process that destroys all microorganisms
(including bacterial microspores).
 The skin could never be sterilized without its own
destruction.

3.
Disinfection
 A process which destroys only the vegetative
forms of organisms =basically clean.
 A disinfectant (germicide, antiseptic): any
chemical substance with either a bactericidal or
a bacteriostatic action.
 Antiseptic -- Agent applied to living tissue
 Disinfectant -- Agent applied to inanimate
surface

4.
Surgical Disinfection
 This is an essential part of a programme for
the control of infection.
 High Risk Items: as they come in close
contact with broken skin or those that breach
mucous membranes or are introduced into a
sterile cavity.

5.
Methods of Disinfection
 Physical: The most important as they can be relied on to
ensure the sterilization of articles used in the treatment
of patients:
– Thermal: Heat or Steam
– Radiation: infra-red radiation, - rays,  particles
– Filtration:utilizing filters capable of screening out microorganisms
 Chemical: Less effective, used for personnel
– Organic
– Inorganic
 Gaseous disinfectants: very efficient, not routine
– Formaldehyde gas
– Ethylene oxide

6.
Physical Methods of Disinfection
HEAT
DRY HEAT
 Kills by Destructive oxidation of cell constituents
 Surest incineration
 Hot-air oven:
– inefficient, poor conductor of heat, penetrates feebly.
– 160°C for 1 hour: damages fabrics, melts rubber
– Used for: Glassware, oily fluids, powders

7.
Physical Methods of Disinfection
HEAT
MOIST HEAT
Effective at low temperature, in a shorter period
of time
 Boiling: 100°C for 30 minutes
 Pasteurisation: 63°C for 30 minutes
 Tyndallisation: steaming for 20 minutes for 3
successive days
 Steaming under pressure= Autoclaving

8.
Advantages of steam
 Kills by denaturing & coagulating enzymes &
proteins
 More rapid (maximum needed time 45mn) & at
lower temperature
 Condensation of steam leads to liberation of
latent heat which raises the temperature, and
gives more penetration
 Half dense as air, so has better penetration

9.
Steam Sterilization: Autoclave
 Principle: An autoclave is a self locking
machine that sterilizes with the high
temperature that steam under pressure
can reach.
 High-vacuum pumps remove as much as
possible air before the steam is admitted,
so the required temperature is reached
very rapidly.

10.
Steam criteria
 Dry: no suspended droplets of water
 Close to its point of condensation: not
superheated
 Free from air: as it decreases the temperature
and the penetration
 Temperature
– 121°C: 15mn-30mn
– 134°C: 4-7mn Flashing

11.
Steps of autoclaving
 Water in the surrounding container full and heated
 Articles in cabinet, doors bolted
 Vacuum to evacuate as much air as possible
 Steam is admitted at a high pressure of and when the
thermometre reaches the required temperature,
sterilisation begins
 Sterilisation is continued for the required time and then
the steam is turned off.
 Drying is carried-out by reapplying a vacuum to evacuate
the steam, introducing dry filtered air into the cabinet (for
15 minutes).

12.
Efficient Autoclaving
 All instruments must be double
wrapped in linen or special paper or
placed in a special metal box
equipped with a filter before
sterilization.
 The white stripes on the tape change
to black when the appropriate
conditions (temperature) have been
met.
 Expiration dates should be printed on
all equipment packs.
 There should be a uniform
development of bars throughout the
length of the strips.
 Ready made plastic bags with strips
printed with a sensitive ink.

13.
Control of autoclave efficiency
 Bowie-Dick test: Used for high-vacuum autoclaves, Done
every day:
– In the middle of a test pack of towel, a paper on to which a strip of
a specific tape is put, for testing.
– Uniform development of dark color indicates that the steam has
passed freely and rapidly to the center of the load.
 Biological sterilization indicators: Spores of a non-
pathogenic organism: Done weekly
– They are killed at 121°C after 15 minutes.
– Attempts to culture them is subsequently made

14.
CHEMICAL DISINFECTION
A SATISFACTORY AGENT SHOULD:
 Be active against a wide range of organisms and
spores. Only few are truly sterilizer
 Have a rapid action
 Should not be toxic or irritant to the skin
 Should be Persistent
There is no one disinfectant which can be
used to kill all micro-organisms in all
situations.

15.
Types of Chemical disinfectants
 Inorganic:
– Iodine
– Chlorine
 Organic:
– Alcohols
– Aldehydes
– Phenols
– Cationic surface-active agents

16.
Inorganic disinfectants
The halogens: Chlorine and Iodine
 Have a rapid action against vegetative
organisms and spores= true sterilizers
 Their action is annulled by foreign organic
material

17.
Iodine disinfectants
The broadest spectrum of all topical anti-infectives, with action
against bacteria, fungi, viruses, spores, protozoa, and yeasts.
 Tincture iodine:
– 2.5% iodine & 2.5% potassium iodide in 90% ethanol.
– Best skin disinfectant
– Irritating to raw surfaces: due to its alcoholic component
– Allergic dermatitis
 Iodophors: Solutions of iodine in non-ionic detergents= Povidone
iodine= Betadine
– Less irritating and less staining
– Less disinfectant than tincture

18.
Chlorine disinfectants
 Powerful, Disinfect water
 Particularly active against viruses
 Concentrated solutions too corrosive
 Usually diluted with a compatible detergent

19.
Organic Disinfectants
 Alcohols: bactericidal: 50-70% ethanol
 Aldehydes:
– Formalin: irritant, powerful=sterilizer
– Glutaraldehyde: less irritant, not volatile, more rapid action.
 Phenols: continued activity in organic matter as human
excreta.
– Phenol: Toxic, expensive
– Cresols: Lysol
– Chloroxylenol: Dettol
– Chlorhexidine: Hibitane- Alkanol
– Hexachlorophane
 Cationic surface-active agents:
– Cetrimide: Cetavlon

20.
Alcohol
 Isopropyl Alcohol 70% (or Ethyl Alcohol 90%)
ADVANTAGES:
 Causes protein denaturation, cell lysis, and metabolic
interruption.
 Degreases the skin.
DISADVANTAGES:
 Ineffective against bacterial spores and poorly effective
against viruses and fungi.

21.
Glutaraldehyde (Cidex)
Cold Sterilization:
 Instruments must be dry before immersion.
 Glutaraldehyde is bactericidal, fungicidal,
viricidal, and sporicidal
 Sterilization: a 10 hour immersion. This
prolonged chemical action can be more
detrimental to surgical instruments.
 3 hours exposure time is needed to destroy
spores.
 If the instruments need to be "disinfected"
only, cold sterilization is okay as
disinfection will take place in only 10
minutes.

22.
Lysoformin
 Formaldehyde & glutaral
 Lysoformin: liquid concentrate with which any dilution
required can be made by simply adding water (20ml + 4-
8L)
 The timing depends on the concentration used:
– flexible endoscopes
– deactivation of HBV & HIV
 Used for heat labile instruments and cleaning
 Does not harm metal instruments
1.5 % - 30 min
2.0 % - 15 min

23.
Sterility Check List
Before assuming a pack is sterile, always
evaluate the following before opening the
pack:
 Expiration date
 Indicator color change
 General condition of wrapper and how it
had been stored
 Always check for holes or moisture damage

24.
Standards for
Surgical Scrubbing, Gowning and
Gloving
 The pre-surgical practice of scrubbing,
gowning and gloving is integral to the
minimization of risk of infection from micro-
organisms present in the wound at the time
of surgery.

25.
Accessing to the operating theatre
 Wear prescribed
operating suite attire
 Remove jewellery
 Keep fingernails short,
clean, healthy
 Wear appropriate
protective attire: masks,
head, overshoes..

26.
REMEMBER
 What went inside the machines is
the STERILISED material
 Personnel are only DISINFECTED

27.
THANK YOU