Informative presentation on Sterilization techniques - useful for Medicine & Health Science educational streams.

1. Sterilization Techniques
presterilizing preparation of medical instruments

2. What is sterilization technique?
 It is a technique that include all the means used to eliminate or destroy living
microorganisms( such as, fungi, bacteria, viruses, spore forms) completely
from the surface.
 Sterilization can be achieved through the application of heat, chemicals,
irradiation, high pressure or filtration.
 It is required for medical devices penetrating sterile body sites, parenteral
fluids and medications.

3. Quality control parameters for the sterilization process:
 Load number
 Temperature and time exposure
 Regular physical/chemical techniques(daily)
 Regular biological testing (weekly)
 Steam processing
 Ethylene oxide processing

4. Following records must be maintained
for all type of sterilization, there are:
 Date of service
 Model and serial number
 Location
 Description of replaced parts
 Biological testing records
 Name and signature of the controller

5. Benefits of sterilizing medical
equipment:
 Eliminate pus, blood, foreign particles and dirt left behind that could lead to
dangerous complications
 It decreases bioburden- the number of non-sterilized bacteria living on a
surface
 It prevents the corrosion of expensive and highly precise tools
 It removes the breeding ground for the surviving germs
 It ensures the safe transport of equipment needing to be packed and
assembled for sterilization

6. Levels of sterilization
 Critical objects- includes surgical instruments that come in contact with
sterile tissue
 Semi-critical objects-includes endoscopes that come in contact with mucous
membranes
 Non-critical objects- includes stethoscopes that come in contact with only the
intact skin

7. Methods for sterilizing medical
equipment
 Thermal sterilization:
Wet sterilization: exposure to steam saturated with water at 121 Celsius for 30
minutes or 134 Celsius for 13 minutes in an autoclave.
Dry sterilization: exposure to 160 Celsius for 120 minutes or 170 Celsius for 60
mintues.this process is often considered less reliable than the wet sterilization
for hollow medical devices.

8.  Chemical sterilization:
It is not always appropriate to heat because it can damage heat sensitive materials such as, biological
materials, fiber optics and plastics.
Low temperature gas sterilizers function by exposing the article to high concentration (5-10%) of very
reactive gases (alkylating agents –ethylene oxide and oxidizing agents such as hydrogen peroxide and
ozone)
Liquid sterilant and high disinfectant typically include oxidizing agents such as hydrogen peroxide and
aldehydes such as glutaraldehyde and ophthalaldehyde.
Once sterilized, rinse off the equipment and allow it to dry. Chemical sterilization isn’t suitable for
biological materials and fiber optics.

9.  Steam sterilization utensils:
Widely used method for heat sterilization is the autoclave, which is also called the converter.
Autoclave commonly use steam heated to 121 – 134 Celsius for a holding of 15 minutes for 121 C or 3
minutes for 134 C.
Additional sterilizing time is required for liquids and instruments packed in layers of cloth as they may
take longer to reach the required temperature. Proper autoclave treatment will inactivate all fungi,
bacteria, viruses and bacterial spores, But it will not necessarily eliminate all prions.
Autoclave sterilization uses coagulation in the form of highly-pressurized steam to denature the
proteins inside of the microorganisms.

10.  Radiation sterilization :
It includes electron beams, x-rays, gamma rays or subatomic particles.
Gamma rays:
They are deeply penetrating and commonly used for sterilization of disposable medical equipment such
as syringes, needles, cannulas and IV sets. Gamma radiation requires bulky shielding for safety and a
storage of radioisotope which continuously emits gamma rays.
X-rays:
It’s the form of ionizing energy allowing to irradiate large packages and pallet loads of medical
devices.it is sufficient to treat multiple pallet loads of low-density packages with very good dose
uniformly ratios.it does not require chemical or radio active materials.
Electron beams:
This uses on-off technology and a much higher dosing rate than gamma or x rays . Less exposure time is
needed but electron beams are less penetrating than gamma or x rays.

11.  Ultraviolet light irradiation (UV, from a germicidal lamp)
It is useful only for sterilization of surfaces and some transparent objects. Many objects which are
transparent to visible light absorb UV. This method is used to sterilize the interiors of biological safety
cabins but its ineffective in shaded areas (under dirt) and also damages many types of plastics.
Irradiation with X-rays or gamma rays does not make materials radioactive.
 Sterile Filtration:
Clear liquid that would be damaged by heat, chemical, or irradiation sterilization can be sterilized by
mechanical filtration. This method is used for sensitive pharmaceuticals and protein solution in
biological research.
A filter with pore size 0.2micrometers will effectively remove bacteria and for viruses pore size around
20nm is needed. Prions are not removed through filtration.
Filtration equipment can be purchased as pre-sterilized disposable units or must be sterilized by
autoclaving before use.