Physical methods of sterilization include heat, radiation, filtration, and chemical agents. Heat-based methods like autoclaving use high temperatures to kill microbes through protein denaturation. Radiation methods employ UV light or gamma rays which damage microbial DNA. Filtration removes microbes by trapping them in fine pore membranes or filters. Sterilization is important in healthcare and food production to prevent transmission of disease and control microbial growth.
1. PHYSICAL METHODS OF STERILIZTION
TEACHER :- DR SHAHIDA MANGI
SUB:- MICOBIOLOGY
IMRAN UL HASSAN SOLANGI
ROLL NO:- ZO-0119-046
Session 2019
Department of ZOOLOGY
SHAH ABDUL LATIF UNIVERSITY ( SALU)
KHAIRPUR
3. INTRODUCTION
Sterilization:-
Sterilization refers to any process that eliminates, removes, kills, or deactivates all forms of life and
other biological agents(such as fungi, bacteria, viruses, spore
forms, prions, unicellular eukaryotic organisms such as Plasmodium, etc.) present in a specified
region, such as a surface, a volume of fluid, medication, or in a compound such as biological culture
media.[1][2]Sterilization can be achieved through various means,
including: heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct
from disinfection, sanitization, and pasteurization, in that sterilization kills, deactivates, or eliminates
all forms of life and other biological agents which are present.
Define Sterilization
Destruction of all living organisms including vegetative forms of bacteria and spores.
What are the 3 musts of sterilization?
1. Must destroy all microbial life.
2. Must not leave toxic residues.
3. Must not cause instrument damage.
Define disinfection:
destruction of most pathologic microbes on inanimate objects.
define Antisepsis:
destruction of most pathologic microbes on animate objects.
4. TERMS USED IN STERILIZATION
Sterilize:- To kill or remove all microorganisms and their spores.
Disinfectant:- Germicidal agent used on inanimate objects, such as a tabletop.
Aseptic:- Sterile
Asepsis:- Removal and or prevention of microbes.
Sepsis:- Illness due to presence of pathogenic microbes and their toxins in the body
Vector:- A living agent that transmits a microbe (lice)
Fomite:- A contaminated object that transmits a microbe, such as a tabletop
Sanitize:- To reduce the bacterial contamination to a level consistent with safety--does not kill
the organism
Sporicide:- Chemical or physical agent used to kill spores
Spores:- The most resistant form of life, if you kill spores, you kill everything
Nosocomial infection:- A hospital acquired infection
Germicide:- Chemical agent that kills vegetative cells of microorganisms
Sterile:- Free from all living microorganisms
ETO:- Ethylene Oxide - very flammable and explosive
Order of Efficiancy of sterilization by heat:-
a. autoclaving -steam under pressure
b. steam at atmospheric pressure
c.boiling water
d.dry heat under pressure
e. dry heat at atmospheric pressure
f. water below its boiling point (pasteurization)
Reverse isolation
when patient is ill due to cancer, aids (any type of immuno deficiency)etc. and needs to be kept
away from our germs.
ETO typical cycle
a. temp. 54.4 degrees Celsius
b. 30-70% RH
c.pressure 5-7 psi
d. conc. 450mg eto/l of air
e. time 6 hours
Denaturization
to alter the protein's structure chemically causing it to lose some or all of its specific
characteristics
autoclaving cycles
a. 121C at 15 psi for 15 min
b. 126C at 20 psi for 10 min
c. 134C at 29.4 psi for 3 min
ETO indicator tape
shows equipment was exposed to ETO
Aeration time after ETO sterilization
24 hours for most materials, 7 days for PVC, neoprene, rubber--absorbs
ETO
Methods of sterilization - heat
most common for respiratory equipment, practical and efficient method.
Heat - important factors to ensure sterilization
1) temperature
2) length of exposure
a. increased temp=decreased exposure time
b. heat sterilization must be sufficient enough to kill most resistant spores.
5. METHODS OF STERILIZATION
1. • Heat (Dry and moist):-
Dry Heat:
Causes denaturation of proteins and oxidative damage.
Techniques include:
• Red Heat (common uses: straight wires, bacterial loops and spatulas)
• Flaming (Common uses: bacterial loops, wires and spatula’s)
• Incernation (common uses: soil dressing, pathological bedding)
• Hot Air oven (discovered by Louis Pasteur, common uses: in dairy industry)
• Infra red rays (common uses: heat glassware and metallic instruments)
Moist Heat:
Moist heat is more efficient in contrast to dry heat; it causes coagulation and denaturation of proteins.
At temperature below 100°C:
• Pasteurization: Food(dairy) Industry
• Vaccine bath: (vaccine sterilization)
• Serum bath: (serum contaminants, does not kill spores survive)
• Inspissation: (egg and serum containing media, can kill spores)
At temperature 100°C:
• Boiling: Boiling water (100°C)
• Steam (100°C)
At temperature above 100°C:
• Autoclave
2. Sun Light:-
Direct sunlight is a natural method of sterilization of water in tanks, rivers, and lakes.
Direct sunlight has an active germicidal effect due to its content of ultraviolet and heat
rays.
Bacteria present in natural water sources are rapidly destroyed by exposure to sunlight.
Possesses bactericidal activity. Action – Content • UV rays, • most oil which are screened
out by glass • presence of ozone in outer regions of atmosphere.
3. • Vibration:-
Sound waves of frequency >20,000 cycle/second kills bacteria and some viruses on exposing for one hour.
Microwaves are not particularly antimicrobial in themselves, rather the killing effect of microwaves are largely
due to the heat that they generate. High frequency sound waves disrupt cells. They are used to clean and
disinfect instruments as well as to reduce microbial load. This method is not reliable since many viruses and
phages are not affected by these waves.
4. • Radiation:-
There are 2 types of Radiation:
Non-ionizing: wavelength longer then visible light.
6. • UV Radiation has a wavelength of 200-280nm; it has a germicidal effect on microorganisms.
• Common uses: Surface disinfection, in hospitals, operating theatre and laboratories.
Ionizing: 2 types:
• Particulate (Electron beam)
• Common uses: sterilisation of instruments such as syringes, gloves, dressing packs, foods and
pharmaceuticals.
• Electromagnetic (Gamma rays)
• Common uses: sterilisation of disposable petri dishes, plastic syringes, antibiotics, vitamins, hormones and
fabrics.
The Other physical methods used in sterilization do not kill all the organisms hence considered to be a form of
disinfection. Refer to the disinfection question.
5. • Filtration:-
In this method, liquids are filtered through bacterial filters to remove any microbes present. This method is
very effective for sterilization of heat sensitive liquids. The chances of clogging and long time duration for the
process to happen are drawbacks.
For sterilization three types of filters are used:
A) Membrane filters: These are thin filters which are made of cellulose. They can be employed for
online sterilization during injection by placing the membrane between the syringe and needle. Used for
sterilization of solvents, gasses.
B) Seitz filters: These are made of asbestos or other material. They are pad like and thicker than
membrane filters. They do not rupture during filtration. But the solution might get absorbed by the filter
pad itself.
Sintered glass filters: These are made of glass and hence do not absorb liquids during filtration. The
disadvantage is that they are very brittle and break easily.
c) Candle filters: These are made of clay like diatomous mud. This special mud has minute pores
made by algae. The filters have many minute lengthy pores. The microbes get stuck during their travel
through the pore in the candle.
7. IMPORTANCE OF STERILISATION
A method employed to minimize the growth of organisms and transmission of disease from
one individual to another. In the environment the use of disinfection techniques decreases
the growth of bacteria on surfaces, which leads to the decrease in transmission of organisms
amongst the population. These techniques are commonly used today in medical care and
food industry.
1. To reduce the risk of contamination on surgical apparatus
2. To minimize the growth of organisms on culture medium.
3. Control diseases by killing some germs like deadly Bacteria, Fungi & Virus
4. It also minimizes some biological changes on organisms.
Pharmaceutical Importance of Sterilization:-
Moist heat sterilization is the most efficient biocidal agent. In the pharmaceutical industry it
is used for: Surgical dressings, Sheets, Surgical and diagnostic equipment, Containers,
Closures, Aqueous injections, Ophthalmic preparations and Irrigation fluids etc.
• Dry heat sterilization can only be used for thermo stable, moisture sensitive or moisture
impermeable pharmaceutical and medicinal. These include products like; Dry powdered
drugs, Suspensions of drug in non aqueous solvents, Oils, fats waxes, soft hard paraffin
silicone, Oily injections, implants, ophthalmic ointments and ointment bases etc..
Gaseous sterilization is used for sterilizing thermolabile substances like; hormones, proteins,
various heat sensitive drugs etc.
• U.V light is perhaps the most lethal component in ordinary sunlight used in sanitation of
garments or utensils.
• Gamma-rays from Cobalt 60 are used to sterilize antibiotic, hormones, sutures, plastics
and catheters etc.
Filtration sterilizations are used in the treatment of Heat sensitive injections and ophthalmic
solutions, biological products, air and other gases for supply to aseptic areas. They are
also used in industry as part of the venting systems on fermentors, centrifuges, autoclaves
and freeze driers. Membrane filters are used for sterility testing
8. External links/References
Introduction of sterilization:-
https://en.wikipedia.org/wiki/Sterilization_(microbiology)
https://quizlet.com/18244345/4-physical-chemical-methods-of-sterilizaiton-flash-cards/
Intro pic :-
https://en.wikipedia.org/wiki/File:Der_Apparat_zur_Sterilisierung_der_Operationsinstrumente_-
_CH-BAR_-_3240236.tif
Terms used in sterilization:- https://quizlet.com/2910135/sterilization-terminology-flash-
cards/
Physical method Of Sterilization:- https://www.wikilectures.eu/w/Sterilization
Sunlight:- https://microbiologyonlinenotes.com/sterilization/
Vibration:- http://microbiologyon-line.blogspot.com/2009/09/ultrasonic-vibrations.html
Filtration:-https://bohatala.com/physical-and-chemical-method-of-
sterilization/
IMPORTANCE OF STERILIZATION:- https://www.wikilectures.eu/w/Importance_of_Sterilisation
https://www.slideshare.net/saivivekkosaraju/sterilization-methods-32401134?from_action=save
Thank you Pic :- https://www.dreamstime.com/stock-illustration-thank-you-d-people-man-person-
amarker-image58790007
