Cleaning, disinfection, and sterilization are important processes to remove microorganisms. Cleaning removes debris, while disinfection kills pathogens but not bacterial spores. Sterilization kills all microbes including spores. Physical methods like heat and radiation can kill microbes by disrupting proteins and membranes. Chemical disinfectants use different mechanisms like oxidation or interrupting DNA synthesis. The level of disinfection or sterilization required depends on the intended use and potential for infection per the Spaulding Classification. Proper evaluation of disinfectants includes factors affecting efficacy.
2. Cleaning
3/31/20192
A form of decontamination by
removing organic matter, salts, and
visible soils
Physical action of scrubbing with
detergents or surfactants and rinsing
with water
Necessary step prior to sterilization or
disinfection
Prof Dr Muhammad Tauseef Jawaid
3. How can microorganisms
be killed?
3/31/20193
Denaturation of proteins (e.g. wet heat,
ethylene oxide)
Oxidation (e.g. dry heat, hydrogen peroxide)
Filtration
Interruption of DNA synthesis/repair (e.g.
radiation)
Interference with protein synthesis (e.g.
bleach)
Disruption of cell membranes (e.g. phenols)Prof Dr Muhammad Tauseef Jawaid
4. Disinfection
3/31/20194
Disinfection is done to
eliminate as many
microorganisms from an item
or from the environment as
possible, but does not
eliminate spores. Disinfection
is used when items cannot or
needn’t be sterilized or in
situations where no method ofProf Dr Muhammad Tauseef Jawaid
5. Disinfection
3/31/20195
“Spaulding’s* three levels of disinfection:
High-level
Intermediate-level
Low-level
*for treatment of devices and surfaces that do
not require sterility for safe use
Prof Dr Muhammad Tauseef Jawaid
6. The effects types of disinfectants
3/31/20196
Effects level Disinfectants
examples
High level Ethylene oxide,
peracetic
acid ,kinds of
aldehyde
Intermediate-level Kinds of alcohol,
kinds of iodine,
chloric
disinfectants
Low level Chlorhexidine,
phenolic
disinfectants
Prof Dr Muhammad Tauseef Jawaid
7. High-level Disinfection
3/31/20197
Includes powerful sporocidal chemicals
(glutaraldehyde, peracteic acid and hydrogen
peroxide)
Inactivates all vegetative bacteria,
mycobacteria (TB), viruses, fungi, some
bacterial spores, enveloped and non
enveloped viruses
Utilize for items that come into contact with
intact mucous membranes and are heat
sensitive
semi-critical medical instruments (s/a
flexible fiber optic endoscopes)
thermometersProf Dr Muhammad Tauseef Jawaid
8. Intermediate-level Disinfection
Includes Chlorine-containing compounds,
alcohols (small surfaces), some phenolics,
and some iodophors
Inactivates a highly resistant organisms
and exhibits some sporcidal activity
Utilize for non-critical medical equipment
s/a stethoscopes, blood pressure cuffs,
dialysis machines, equipment knobs and
controls.
3/31/20198 Prof Dr Muhammad Tauseef Jawaid
9. Low-level Disinfection
3/31/20199
Includes quaternary ammonium compounds,
some phenolics, and some iodophors
Inactivates vegetative bacteria, fungi, and
some lipid enveloped medium size viruses
Utilize for items that come in contact with
intact skin such as examining table top, baby
weigh scale, blood pressure cuff
Prof Dr Muhammad Tauseef Jawaid
10. Hand Hygiene
3/31/201910
Avoid artificial nails and keep natural nails
< ¼ in
For visibly soiled hands use soap and
water
Use alcohol-based handrubs
Before and after each patient
Before and after glove use
Improved hand hygiene adherence has:
Terminated outbreaks in health care
facilities
↓ transmission of AR organismsProf Dr Muhammad Tauseef Jawaid
13. Physical Methods of Microbial Control
3/31/201913
Exposure to extremes of heat
Exposure to extremes of cold
Desiccation(To dry out thoroughly.)
Filtration.
Osmotic pressure.
Radiation.
Microwave disinfection sterilization.
Mechanical methods .
Prof Dr Muhammad Tauseef Jawaid
14. Heat-Related Methods
3/31/201914
Effects of high temperatures
Denaturation of proteins
Interference with integrity of cytoplasmic
membrane and cell walls
Disruption of structure and function of nucleic
acids
Thermal death point – lowest temperature that
kills all cells in broth in 10 minutes
Thermal death time – time to sterilize volume of
liquid at set temperature
Prof Dr Muhammad Tauseef Jawaid
15. Moist Heat
3/31/201915
Used to disinfect, sanitize, and sterilize
Kills by denaturing proteins and destroying
cytoplasmic membranes
More effective than dry heat; water better
conductor of heat than air. Moist heat is also more
penetrating than dry heat
Methods of microbial control using moist heat
Boiling
Autoclaving
Pasteurization
Ultrahigh-Temperature Sterilization
Prof Dr Muhammad Tauseef Jawaid
16. Boiling
3/31/201916
Kills vegetative cells of bacteria and fungi,
protozoan trophozoites, and most viruses within 10
minutes at sea level
Temperature cannot exceed 100ºC at sea level;
steam carries some heat away
Boiling time is critical
Water boils at lower temperatures at higher
elevations; requires longer boiling time
Endospores, protozoan cysts, and some viruses
can survive boiling
Prof Dr Muhammad Tauseef Jawaid
17. Autoclaving
3/31/201917
Pressure applied to boiling water prevents steam
from escaping
Boiling temperature increases as pressure
increases
Autoclave conditions – 121ºC, 15 psi, 15 minutes
Volume
Contact
Wrapping
Testing
Prof Dr Muhammad Tauseef Jawaid
20. Hot air drying
3/31/201920
Make use of the specially made hot air drying oven to
sterilize, the heat power spread and penetration
depends on the air convection and medium
conduction, and the effect of this method is reliable
Suitable for
the articles that do not change in character ,do not
damage and do not evaporate under high
temperature.
For example: oil, powder ,glass products and metal
products,etc.
Not suitable for
Fiber products, plastics productsProf Dr Muhammad Tauseef Jawaid
21. Illumination disinfection(radiation
sterilization)
3/31/201921
Make use of the
ultraviolet rays
to photolyze
and
denaturalize the
bacteria’s
protein and lead
the bacteria’s
Insolation under
the sun
Ultraviolet lamp
disinfection
Ozone lamp
Prof Dr Muhammad Tauseef Jawaid
22. Insolation under the sun
3/31/201922
Commonly used for mattress,
carpet,clothes,books.
Method:insolate the articles
directly under the sun for 6
hours, and turn over the articles
periodically to make each side
of the articles exposure to the
sun
Prof Dr Muhammad Tauseef Jawaid
23. Ultraviolet lamp disinfection
3/31/201923
C wave,
wavelength:200~275nm, the
most effective:250~270nm
Ultraviolet rays can kill
bacillus, virus fungus,
bacterial vegetative form,
spores.
Prof Dr Muhammad Tauseef Jawaid
24. Ozone lamp
3/31/201924
This method can be used to kill
bacterial vegetative form, virus,
spores, fungus and destroy botulin
Mainly used to air disinfection,
hospital dirt water disinfection and
articles surfaces disinfection
Prof Dr Muhammad Tauseef Jawaid
25. Chemical Disinfection
Sterilization
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The chemicals used for
disinfection are called as
disinfectants. The effects of
some disinfectants are enough
strong to sterilize, these
disinfectants are also called as
sterilants.Prof Dr Muhammad Tauseef Jawaid
26. Chemical disinfectants use
principles
3/31/201926
Select the proper disinfectants according to the
types of the objects to be disinfected and the
characters of the microorganisms to be killed
Strictly control the effective concentration of the
disinfectants and the disinfection time , the use
methods
The disinfectants should be changed
periodically, the disinfectants which vaporize
easily should be covered and examine and
regulate its concentration
Prof Dr Muhammad Tauseef Jawaid
27. Chemical disinfectants use
principles
3/31/201927
The objects must be cleaned and dried
beforehand
There should not be the gauzes, cotton and
so on in the disinfectant solutions, for these
kinds of objects can absorb the disinfectants
so that the effect of the disinfectants can be
weakened.
The objects after being disinfected must be
rinsed with physiological saline() before use to
protect body tissues from the disinfectants’
irritatingProf Dr Muhammad Tauseef Jawaid
28. use methods of chemical
disinfectants
3/31/201928
Immersion:
Firstly, clean the articles to be disinfected, secondly,
dry the articles, then, immerse the articles into the
disinfectant solution..
Immersion time and the concentration of the
solution should be according to the provision.
Prof Dr Muhammad Tauseef Jawaid
29. use methods of chemical
disinfectants
3/31/201929
Rubbing:
Which is the method to use the chemical
disinfectants to rub the surfaces of the
contaminated articles or the method to disinfect
the skin.
e.g:using iodophor of 0.5%~1.0% to disinfect skin;
using chloric disinfectants to rub the walls and the
floors.
Prof Dr Muhammad Tauseef Jawaid
30. use methods of chemical
disinfectants
3/31/201930
Nebulization
The method is that using a nebulizer spray the
chemical disinfectants evenly on the surfaces of
articles or the air.
The method is commonly used for the disinfection
of floors, walls, and environment, etc.
Attention to wet the articles’ surfaces well when one
spray.
Prof Dr Muhammad Tauseef Jawaid
31. use methods of chemical
disinfectants
3/31/201931
Fumigation
The method means creating air to disinfect
through heating a disinfectant or add oxidants
into it.
The method is commonly used for disinfection
of space, e.g: the space of operation rooms,
dressing rooms and wards.
And in the closed containers this method can
also be used to disinfect the contaminated
articles.
The formaldehyde gas and ethylene oxide gas
Prof Dr Muhammad Tauseef Jawaid
32. Chemical Methods of Microbial Control
3/31/201932
Major Categories
Phenols
Alcohols
Halogens
Oxidizing agents
Surfactants
Heavy Metals
Aldehydes
Gaseous Agents
Antimicrobics
Prof Dr Muhammad Tauseef Jawaid
33. Factors that influence efficacy of
disinfection/sterilization
3/31/201933
Contact time
Physico-chemical environment (e.g. pH)
3 Presence of organic material
4 Temperature
5 Type of microorganism
6 Number of microorganisms
7 Material composition
Prof Dr Muhammad Tauseef Jawaid
34. Ideal sterilization/disinfection process
3/31/201934
Highly efficacious
Fast
Good penetrability
Compatible with all materials
Non-toxic
Effective despite presence of organic
material
Difficult to make significant mistakes in
process
Easily monitored
Prof Dr Muhammad Tauseef Jawaid
35. Spaulding Classification
Category Description Requirement
Critical Enters sterile body cavity Sterile
Semi-critical Contacts mucous
membranes, non-intact
skin
High level
disinfection
Non-critical Contacts intact skin Low level
disinfection
3/31/201935 Prof Dr Muhammad Tauseef Jawaid
37. Sterilization process
3/31/201937
Clean items
Package items
Load sterilizer
Monitor
Physical (time/temp/pressure)
Chemical
Biological
Storage post-sterilization
Documentation
Prof Dr Muhammad Tauseef Jawaid
38. Problems with sterility
3/31/201938
Lack of understanding of risk/process
physicians introducing new products (borrowed,
samples)
Multidose vials
What is sterile vs not
Lack of understanding of components of
process
MDs, technologists have less training than nurses
(anaesthesiology, imaging, urology)
Prof Dr Muhammad Tauseef Jawaid
39. Flash Sterilization
3/31/201939
Unwrapped objects,
132°C, 3mins, 27-28lbs
pressure in gravity
Acceptable for
processing items that
cannot be sterilized and
stored before use
Prof Dr Muhammad Tauseef Jawaid
40. Problems with semi-critical items
3/31/201940
Complex and delicate pieces of
equipment
Expensive equipment used frequently
Centralizing process difficult
Time an important factor
Absence of regulation/guidance for
design
Narrow margin of safety
Prof Dr Muhammad Tauseef Jawaid
41. Methods for Evaluating Disinfectants
and Antiseptics
3/31/201941
Phenol Coefficient
Use-Dilution Test
Disk-Diffusion Method
In-Use Test
Prof Dr Muhammad Tauseef Jawaid
42. Phenol Coefficient
3/31/201942
Evaluating the efficacy of disinfectants and
antiseptics by determining the ratio of
agent’s ability to control microbes to that of
phenol
Greater than 1.0 indicates that agent is more
effective than phenol
Has been replaced by newer methods
Prof Dr Muhammad Tauseef Jawaid
43. Use-Dilution Test
3/31/201943
Especially useful for determining the ability of
disinfectants to kill microorganisms dried onto a
typical clinical surface (stainless steel)
Metal cylinders dipped into broth cultures of
bacteria and dried
Contaminated cylinder immersed into dilution of
disinfectant for 10 minutes
Cylinders removed, washed, and placed into tube
of medium for 48 h
Most effective agent entirely prevents growth at
highest dilution
Prof Dr Muhammad Tauseef Jawaid
44. Disk-Diffusion Method
3/31/201944
A method that requires less manipulation to judge
the efficacy of disinfectants
Here filter paper is soaked with disinfectant and
then simply placed on the agar surface of a petri
dish that has been inoculated with a lawn of test
organism
The clear area around the disk following incubation
is used as an indication of disinfectant efficacy
Prof Dr Muhammad Tauseef Jawaid
46. In-Use Test
3/31/201946
Swabs taken from objects before and after
application of disinfectant or antiseptic
Swabs inoculated into growth medium and
incubated
Medium monitored for growth
Accurate determination of proper strength
and application procedure for each specific
situation
Prof Dr Muhammad Tauseef Jawaid