The document discusses sterilization and disinfection, outlining methods such as physical (heat, radiation, filtration) and chemical (inorganic, organic agents) approaches. It emphasizes the importance of surgical disinfection processes, particularly high-risk items, and details the operation and effectiveness of autoclaves. Additionally, it provides guidelines for chemical disinfectants, their actions, and standards for surgical scrubbing, gowning, and gloving.

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