Sterilization its's definitions & basic mechanism on how it works & what it does

1. STERILIZATION
Presented by :-
Karim Yousry Basiuony

2. Table Of Contents
Definition of Sterilization & Disinfection
Types Of Disinfection
Steps Of Sterilization
Methods of Sterilization

3. Introduction
 Healthcare-associated infections are an
important cause of morbidity and mortality in
hospitals.
 Each year more than 2million patients
acquire healthcare-associated infections,
resulting in 90,000 deaths

4.  Millions of surgical procedures and invasive medical
procedures are performed each year.
 Each procedure involves contact by a medical
device or surgical instrument with a patient’s sterile
tissue or mucous membranes.

5. What is the risk
 A major risk of all such procedures is the
introduction of pathogens that can lead to
infection.
 Failure to properly disinfect or sterilize
equipment carries not only risk associated
with breach of host barriers but also risk
for person-to-person transmission (e.g.,
hepatitis B virus) and transmission of
environmental pathogens (e.g., Pseudomonas(

6.  Disinfection and sterilization are essential for
ensuring that medical and surgical instruments do
not transmit infectious pathogens to patients.
 health-care policies must identify, primarily on
the basis of the items' intended use,
whether cleaning, disinfection, or
sterilization is indicated

7. Sterilization
 Sterilization is a process that destroys
or eliminates all forms of microbial life on
item to prevent disease transmission
associated with the use of that item and it
is being carried out in health-care facilities
by physical or chemical means

8. Disinfection
 Disinfection is a process that eliminates
many or all pathogenic microorganisms,
except bacterial spores, on inanimate objects
 In health-care settings, objects usually are
disinfected by liquid chemicals or wet
pasteurization.

9. Types of Disinfection
 High-level disinfection.
 Intermediate-level disinfectants.
 Low-level disinfectants

10. High-level disinfection
 High-level disinfection traditionally is defined
as complete elimination of all microorganisms in or
on an instrument, except for small numbers of
bacterial spores.
 Cleaning followed by high-level disinfection should
eliminate enough pathogens to prevent transmission
of infection.

11. Intermediate-level disinfectants
 Intermediate-level disinfectants
might be cidal for mycobacteria,
vegetative bacteria, most viruses, and
most fungi but do not necessarily kill
bacterial spores

12. Low-level disinfectants
 Low-level disinfectants can kill most
vegetative bacteria, some fungi, and
some viruses in a practical period of
time (<10 minutes).

13. 13
Bacterial Spores
B. subtilis
Mycobacterium
M. tuberculosis
Non-lipid Viruses
Polio-
Rhino-
Fungi
Cryptococcus sp,
Candida sp.
Vegatative Bacteria
Pseudomonas sp.
Staphylococcus
sp.
Salmonella sp.
Lipid Viruses
Herpes
CMV
HBV
HIV
Decontamination Agents – Kill Summary
Sterilization
HLD
LLD
ILD

14. How we eliminate pathogens
From Surfaces &Equipment
 Initial Steps
Wipe and/or wash away organic substances

Blood, etc.
 Sterilization or disinfection

15. Theory of Sterilization:
 1)Denaturation:
Chemical alteration of the cell protein
 2)Coagulation:
Reduce cell protein to a gelatinous mass
 3)Decreased surface tension: (cytolysis)
Surface of the pathogen becomes weak to
fluids which enter cell and cause rupture
 4)Interfere with metabolism:
The cell cannot use or produce energy, so it either dies or cannot
multiply

16. Factors that affect the efficiency of
both disinfection and sterilization
 prior cleaning of the object.
 organic and inorganic load present.
 type and level of microbial contamination
,concentration and exposure time to the germicide.
 physical nature of the object (e.g., crevices, hinges,
and lumens).
 presence of biofilms.
 temperature and pH of the disinfection process.
 and in some cases, relative humidity of the
sterilization process (e.g., ethylene oxide).

17. Resistance of
Microorganisms
 Microorganisms vary greatly in their resistance to
chemical germicides and sterilization processes.
 The most resistant microbial population controls the
sterilization or disinfection time. That is, to destroy
the most resistant types of microorganisms (i.e.,
bacterial spores), the user needs to employ exposure
times and a concentration of germicide needed to
achieve complete destruction.

18. biofilm
 The biofilm life cycle in three steps:
 (1) attachment, (2) growth of colonies, (3)detachment in
clumps.

19. Disinfection and
Sterilization
It can be divided into object’s intended to use by:
 CRITICAL – objects: which enter normally sterile tissue or
the vascular system or through which blood flows should be
sterile.
 SEMICRITICAL – objects: that touch mucous membranes
or skin that is not intact require a disinfection process (high-
level disinfection [HLD] that kills all microorganisms
and high numbers of bacterial spores.
 NONCRITICAL –objects: that touch only intact skin require
low-level disinfection

20. Critical items
 Critical items has a high risk for infection if they are
contaminated with any microorganism.
 Objects that enter tissue or the vascular
system must be sterile because any microbial
contamination could transmit disease.
 This category includes surgical instruments,
cardiac and urinary catheters and ultrasound probes
used in body cavities.

21. TYPES OF CRITICAL
INSTRUMENTS
urinary catheters
ultrasound probes

22. Semicritical items
 items contact mucous membranes or non-
intact skin.
 This category includes respiratory and anesthesia
equipment, some laryngoscope blades , cystoscopies and
diaphragm fitting rings.
 These medical devices should be free from all microorganisms;
however, small numbers of bacterial spores are permissible
 Semicritical items minimally require high-level
disinfection using chemical disinfectants.

23. Respiratory & anesthesia eq
cystoscope
laryngoscope blades
Types of Semicritical instruments

24. Noncritical Items
 Noncritical items are those that come in contact
with intact skin but not mucous membranes
 noncritical items are divided into:
1- noncritical patient care items e.g, bedpans,
blood pressure cuffs, crutches and computers .
2-noncritical environmental surfaces e.g, bed
rails, some food utensils, bedside tables, patient furniture
and floors

25. Types of Noncritical instruments
Blood pressure cuffs Crutches Bedrails

26. Preparation for sterilization
 All instruments must be
double wrapped in linen or
special paper or placed in a
special metal box equipped
with a filter before
sterilization.

27. Methods of Sterilization:
1) Dry Heat -Hot air oven , Heating to
redness , Incineration , Flaming.
2) Wet Heat ---------- Steam sterilization.
(autoclaving)
3) low-temperature sterilization(Gas Plasma)
4) Radiation
5) Filter Sterilization

28. Sterilization BY HEAT
1) DRY HEAT:
 Incineration:
( There must be high temp to complete the operation )
why it’s used on: Too contaminated object or
to clean and the disposable of an object.

29. STERILIZATION BY DRY
HEAT
Hot air oven
 It is a practical way to
sterilize needles ,metals
,glassware , heat resistant
oils and waxes.
 A convection oven with an
insulated stainless steel
chamber and perforated
shelving to allow the
circulation of hot air is
recommended.

30. The Cycle of sterilization By Dry Heat
 Dry heat:
170C for 1 hour:(total cycle time—placing instruments in
oven, heating to 170C, timing for 1 hour, and then cooling
is from 2–2.5 hours).
or
160C (320F) for 2 hours:(total cycle time is from 3–3.5h).

31. Sterilization by heat
2) Wet Heat:
How it works:
moist heat in the form of saturated steam
under pressure is the most widely used and the
most dependable.
Advantages:
Steam sterilization is nontoxic, inexpensive ,
rapidly microbicidal, sporicidal, and rapidly
heats and penetrates fabrics

32. steam sterilization
Autoclave:
The basic principle is to expose
each item to direct steam contact at
the required temperature and
pressure for the specified time.
The two common steam-sterilizing
temperatures are 121oC (250oF)
and 132oC (270oF) in the pressure
chamber at 15 P.S.I.
 ( Four parameters of steam
sterilization)

33. How it works:
Moist heat destroys microorganisms by the
irreversible coagulation and denaturation of enzymes
and structural proteins
Uses:
Steam sterilization should be used whenever possible
on all critical and semicritical items that are heat and
moisture resistant

34. Types of high-pressure
steam sterilizers:
There are three types of high-pressure
steam sterilizers:
 The Gravity displacement
 The high-speed Prevacuum
 The Flash

35. Simplified Diagram of a Gravity
Displacement Steam Sterilizer

36. The gravity displacement
autoclaves
 Uses:
 For gravity displacement sterilizers the
penetration time into porous items is
prolonged because of incomplete air
elimination.

37. The high speed
prevacuum sterilizers
 similar to the former except they are
fitted with a vacuum pump (or ejector)
to ensure air removal before the steam
is admitted.
 The advantage of using a vacuum
pump is that there is nearly
instantaneous steam penetration even
into porous loads.

38. Flash Sterilization
 sterilization of an unwrapped object at 132oC
for 3 minutes at 27-28 lbs. of pressure .

39. 3) Low-Temperature Sterilization
 Heat-sensitive objects
 An ideal low-temperature (<60oC)
sterilant.
low-temperature sterilization
a) Ethylene oxide.
b) Hydrogen peroxide gas plasma.
c) Ozone.
d) liquid chemical sterilants.

40. a) Ethylene oxide
What does ETO stands for :
Ethylene oxide
 Two types of ETO sterilizers are available,
mixed gas and 100% ETO.
 The basic ETO sterilization cycle takes
approximately 2 hrs & consists of five stages :
1- preconditioning and humidification.
2- gas introduction. 3- exposure.
4- evacuation. 5- air washes.

41. Compact One-Chamber
EtO Sterilizee
Uses:
ETO is used in
healthcare facilities to
sterilize critical items (and
sometimes semicritical
items) that are moisture or
heat sensitive and cannot
be sterilized by steam
sterilization

42. b)Hydrogen Peroxide GasPlasma
The mechanism of this device:
the production of free radicals within a plasma
field that are capable of interacting with essential
cell components (e.g., enzymes, nucleic acids)
disrupting the metabolism of microorganisms.
Disadvantages: Expensive

43. c) Ozone
 Ozone is used in industrial settings to
sterilize water and air, as well as a
disinfectant for surfaces.
 It has the benefit of being able to
oxidize most organic matter.
 it is a toxic and unstable gas that must
be produced on-site, so it is not
practical to use in many settings

44. d) liquid chemical sterilants
 A few disinfectants will kill spores with prolonged
exposure times (3–12 hours), these are called
chemical sterilants.
I. Peracetic Acid Sterilization.
II. Cold (Chemical) Sterilization.
III. ortho-phathaladehyde.

45. 4-Radiation Sterilization
Electron beams: commonly used for medical device sterilization.
provide a much higher dosing rate than gamma or x-rays. are less
penetrating than either gamma or x-rays.
Ultraviolet light: sterilization of surfaces and some transparent
objects. sterilize the interiors of biological safety cabinets between uses
X-rays: less penetrating than gamma rays and tend to
require longer exposure times, but require less shielding.
cobalt 60 gamma rays: are very penetrating and are commonly
used for sterilization of disposable medical equipment, such as syringes,
needles, cannulas and IV sets. always presents a hazard in the area of
the facility).
subatomic particles

46. 5(Filter Sterilization
 Filters are used for removal of
microorganisms in fluids and
gases.
 They come in a wide variety of
types and sizes. A 0.2 micron
filter is required to remove
bacteria from fluids.
 The filter is placed in the IV
line or on a syringe, so that the
contaminated solution is
sterilized before reaching the
patient.

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