This document discusses methods of decontamination including cleaning, disinfection, and sterilization. It provides details on various sterilization methods such as steam, dry heat, chemicals, and their advantages and disadvantages. Specific sterilizing agents like ethylene oxide, formaldehyde, and autoclaving are described. The document also covers types of disinfectants like alcohol, phenol, hypochlorite, glutaraldehyde, chlorhexidine, iodophors and quats along with their characteristics and effectiveness against different microorganisms. Monitoring of sterilization using biological and chemical indicators is also mentioned.

1. By
Dr. Yousra El-Maradny
Lecture 6
Disinfection
&
sterilization

2. Decontamination
• Decontamination ‫التلـوث‬ ‫إزالـة‬ is combination of processes to
remove pathogenic microorganisms from an item, making
it safe to handle, use or discard.
• Decontamination is achieved at three levels:
(
‫والتعقيم‬ ‫والتطهير‬ ‫التنظيف‬
)
- Cleaning
- Disinfection(process) Disinfectant (Agent) ‫المطهــرة‬ ‫المــادة‬
- Sterilization (process) Sterilant (Agent) ‫المعقمة‬ ‫المــادة‬
Heat stable critical & semi-critical instruments should
be sterilized between uses.

3. •Cleaning: a process that removes of
foreign material (soil & organic
material) from an object.
Cleaning is essential before
disinfection or sterilization.
‫مباشرة‬ ‫االستخدام‬ ‫بعد‬ ‫التنظيف‬ ‫عملية‬ ‫في‬ ‫البدء‬ ‫يتم‬ ‫أن‬ ‫يفضل‬
(
‫ومنظف‬ ‫ماء‬
‫إنزيمية‬ ‫مادة‬ ‫أو‬ ‫سائل‬
)
‫إرسال‬ ‫لحين‬ ‫منظف‬ ‫محلول‬ ‫في‬ ‫النقع‬ ‫يتم‬ ‫أن‬ ‫أو‬
‫إلى‬ ‫ها‬
‫المركزي‬ ‫التعقيم‬ ‫قسم‬
.
‫االد‬ ‫تجريح‬ ‫لمنع‬ ‫ناعمه‬ ‫فرشاة‬ ‫استخدام‬ ‫يتم‬
‫وات‬
.
‫تجفيف‬
‫االدوات‬
‫مهم‬
‫جدا‬
‫بعد‬
‫تنظيفها‬
.

4. •Disinfection: a process that reduce number of vegetative
microorganisms to a level not harmful to health (below
infective dose) but NOT bacterial spores. (toxic to living
tissues).
•Antiseptic: disinfection of living tissue (skin).
•Sterilization: a process that destroy all microorganisms
including bacterial spores.

5. Sterilization
Physical
Heat
Dry
heat
Hot air
oven
Moist
heat
Autoclave
Radiation Filtration
Chemical
Liquid
Glutaraldehy
de
Hypochl
orite
Gaseous
Ethylen
e oxide
Formald
ehyde

6. Heat sterilization
Moist heat sterilization (steam under
pressure)
Dry heat sterilization
Steam autoclave: uses steam under pressure (15 psi)
for a specific duration
long time at high temperature:
• 180°c for 30 min
• 170°c for 1 hour
• 160°c for 2 hours
• 149°c for 2.5 hours
• 141°c for 3 hours
Temperature: Unwrapped (121°c for 20 min) OR
(134°c for 3min).
Wrapped (121°c for 30 min) OR (134°c for 15min).
Package material requirements:
• Must allow steam to penetrate
• Must not insulate items from heat
• Must not be destroyed by
temperature
Suitable for: most instruments as
paper, plastic, clothes
Mirror - glass container – cutting
metal – aluminum foil
Not suitable for: glass container - mirror (dull),
metal (rust), carbon steel (corrosion)
paper – plastic – liquid

7. Autoclave Hot air oven

8. Method Advantages Disadvantages
Steam
Sterilization
• The most common
• Safe and Nontoxic
• In-expensive
• Short sterilization time
• Heat and moisture sensitive
components can be damaged
Dry Heat
Sterilization
• Low corrosiveness
• Deep penetration ‫اختراق‬
‫عميق‬in the material
• Simple & Safe for the
environment
• long sterilization time
• Heat-labile ‫بالحرارة‬ ‫تتأثر‬
components can be damaged

9. Chemicals sterilization
•E.g., Glutaraldehyde
•Take a very long time (about 10 hours)
•Useful for heat sensitive materials (plastic-
rubber)
Liquid chemical sterilant followed by:
1. Rinsing ‫شط‬
‫ف‬ with sterile water.
2. Drying ‫تجفيف‬ .
3. Placed in sterile container if not used at
time.

10. Method Advantages Disadvantages
100% Ethylene
Oxide (ETO)
•Penetrates packaging
materials
• Compatible with most
medical materials
• Simple to operate and
monitor
• ETO is toxic (carcinogen),
and flammable
Formaldehyde • Not flammable and
explosive
• Compatible with most
medical materials
• Toxic and allergenic

11. Monitoring sterilization
1- Biological indicators (spore test) Weekly
Either biological or chemical.

12. 2- Chemical Indicator
•Change color after exposure to heat
•Chemical indicators alone do not
ensure adequacy of a sterilization.
•Used on the outside of each pack of
instruments OR inside unwrapped
instruments to confirm heat
penetration during sterilization.

13. Disinfection
• By chemical methods (= disinfectants).
• Suitable for inanimate objects.
• kill or reduce the vegetative not the spore forms of all
pathogenic organisms.
• Carried out where absolute sterility is not essential or
not practicable.

14. Criteria of disinfectants
• Easy to use. ‫االستخدام‬ ‫سهل‬
• Non-volatile. ‫متطاير‬ ‫غير‬
• Not harmful. ‫ضار‬ ‫غير‬
• With pleasant smells. ‫طيبة‬ ‫رائحة‬ ‫له‬
• Effective with short time.‫قصير‬ ‫وقت‬ ‫في‬ ‫فعال‬

15. Types of disinfectants
• Alcohols
• Phenol
• Hypochlorite
• Glutaraldehyde
• Chlorhexidine
• Iodophors
• Quats

16. Alcohol
• 70% Ethanol or isopropanol.
• Used as antiseptic rather than disinfectant
• Have limited residual activity due to evaporation.
• Non-corrosive but can be a fire hazard.
• Not effective in presence of organic matter (blood,
pus, feces, vomitus).
• Not effective against fungal or bacterial spores.

17. • Most effective when combined with purified water to
facilitate diffusion through the cell membrane (100% alcohol
denatures only external membrane proteins).
• Effective when in solution with wetting agent (coconut soap)
even against spores if stay contact for 10 min.
• Effective against non-enveloped viruses (HAV) but not all of
them.
• Effective against lipid enveloped viruses (HIV, HCV, HBV)
Alcohol

18. Phenol
•Suitable as 1-2% .
•Cheap.
•Toxic and corrosive. ‫تاكل‬ ‫يسبب‬ ‫و‬ ‫سام‬
‫المادة‬
•Not effective against viruses or
bacterial spores.
•Active in the presence of organic
matter.

19. Hypochlorite
• Chlorine
• Expressed as parts per million (ppm).
• Corrosive.
• Effective against fungi, bacteria &
viruses (HIV, HBV).
• Activity is reduced in the presence of
organic matter.

20. Glutaraldehyde
• E.g., Cidex
• 2% solution.
• Expensive.
• Disinfection is achieved after a contact time
of 20 minutes.
• Prolonged contact of 3 hours or more will
destroy spores, acid fast bacilli and viruses,
achieving sterilization.

21. Chlorhexidine
• E.g., Hibitane
• Used as antiseptic rather than disinfectant.
• Used incorporation with alcoholic hand rub.
• Non-toxic
• Non-corrosive
• Expensive

22. Iodophors
•E.g., Betadine (povidone-iodine).
•Destroy spores.
•Used as antiseptic rather than
disinfectant.

23. Quaternary ammonium
compounds (Quats)
• E.g., Savlon (mixture of cetrimide & chlorhexidine).
• Destroy bacteria.
• Not effective against spores.
• Not effective against organic matter.
• Used as antiseptic rather than disinfectant.

24. Alcohol Phenol Hypochlori
te
Glutarald
ehyde
Chlorhexi
dine
Iodophors Quats
Bacterial
spores X X √ high
concentration
√after 3
hrs
X √ prolonged
contact time
X
Enveloped
Viruses √ X √ √ after 3 hrs √ √ √
Non-
Enveloped
Viruses
≈ X √ -- X √ X
Fungal spores X X √ high
concentration
√after 3
hrs
X √ prolonged
contact time
X
Flammable √ -- X √ X -- --
Antiseptic √ X X X √ √ √
Price Moderate Cheap Cheap Expensive Expensive Moderate Moderate