Complete steps of sterilization method, with all aspects. It will be very helpful for science students.

1. Welcome
STERILIZATION METHODS

2. STERLIZATION
WHAT
How
WHY

3. What is Sterlization ?
Complete Removal/Killing Of Microorganisms like
Bacteria, Fungi, Viruses Or any Pathogens.
WHY it is Essential ?
Before 18th Century Hospital acquired Infections HAI/HCAI-
Helth Care Associated Infections is The Cause of 10%
Surgical Case and 25% Delivering Mother Death.
To Create Aseptic Environment in Modern days Lab Practice
HOW to Sterlize?/METHODS Of Sterlization:
Luis Pasteur discoveries described that the Microbes are the
Cause for Disease. English Physician Joseph Lister et al,
were the first who used Sterilization before medical
procedure.

5. PRESENT DAY STERLIZATION
METHODOS
• PHYSICAL METHODS
Drying, Heating, Radiations and Ultrasonic Vibration
• CHEMICAL:
Alcohol, Aldehydes, Phenols,, Halogens, Oxidising Agents, Heavy Metal Salts, Surface
Active Agens, Dyes and Gas Sterilization.
• MECHANICAL: Filtration

7. DRYING IN DIRECT SUNLIGHT
2 hours exposure kills bacteria like
B. typhii
INCINERATION: 870-
1200°C temp. For Disposal
of medical/biological waste
DIRECT FLAMING: small glassware, metallic utensils
HOT AIR OVEN: Stainless steel electric chamber, used for
glassware and surgical instruments

8. MOIST HEAT STERLIZATION METHODS
TEMPERATURE BELOW 100°C
TEMPERATURE AT 100°C
BOILING : Most common method, 15-20 min. boiling.
STEAMING: At atmospheric pressure for 90 minutes
TYNDALLIZATION: Intermittent Sterilization, 100°C, 30 minutes, 3days for Egg, Serum,
Suger rich media
TEMPERATURE ABOVE 100°C : AUTOCLAVE, 15 minutes at 121°C
PASTEURATION
WATER BATH For Serum, Vaccine,
body fluids

9. AUTOCLAVE: Means “self lock” device,most common Sterilization device, Discovered By C. Chamberland
1879. It works on principle P♾️T when pressure of gas increases temp. also increases equally. It takes 15 minutes at
121°C to sterlize 50 ml volume.
Volume (ml) Time (minutes)
50 15
75 20
250-500 25
1000 30
1500 35
2000 40
Volume (ml)
Time
Volume (ml)
Time
Volume (ml)
Time
Volume (ml)
Time

10. RADIATIONS
Microbial cell get deforms depending upon Wavelength, Intensity and
Duration of exposure.
IONIZING: Short Wavelength, High energy, Rapid action radiation, destructure DNA
without increasing Temperature e.g, X- ray , Gamma rays, Cosmic rays
NON-IONIZING: Low Wavelength, Low energy radiation,but can damage DNA e.g,
Infrared rays, UV rays
Ultrasonic waves/Vibration
High Frequency ultrasonic waves damage bacterial cells,but not very reliable
and widely used.

11. CHEMICAL METHODOS OF STERILIZATION
1. ALCOHALS Denatured proteins, Obstruct membrane, and breakdowns lipids of microbes, e.g, Ethanol
& Isopropanol
2. ALDEHYDES Formaldehyde(more irritant) , Glyceraldehyde(less irritant) formalin have
37%formaldehyde
3. PHENOLS Firstly used by Joseph Lister(1867), Damage lipids of membrane, remain for long
time e.g, Lysol, Cresol, Xylenol. Mostly toxic & irritant but Chlorhexidine used in Savlon is less
irritant. In Dettol Chloroxylenol present

12. CHEMICAL METHODS OF STERILIZATION
6. HEAVY METAL SALTS: e.g, HgCl2 0.1-1% solution, AgNO3 1%solution used in Eye infections,
CuSO4 used to disinfect swimming pools, Silver sulphadiazine used in Burn patients
7. SURFACTANTS: e.g, Soap and Detergents
4. HALOGENSS: e.g, Chlorine & Iodine. Iodine can kill all species of Pathogens (Bacteria, Fungi,
and some strains of Viruses. It impairs synthesis of proteins and Cell membrane. Used in tincher(aquas
solution of Iodine), Betadine, NaOCl(Bleach)- used in food industry, CaOCl2
5. OXIDISING AGENTS: e.g, Hydroxy peroxide – attacks membrane lipids and
DNA, used to sterlize Ventilator, Contact lenses,Tonometer. Peracetic acid- powerful
than Hydroxy peroxide used to sterlize Hemodialysis & Plasma Sterilization

13. 8.DYES: ANILIN e.g, Gentian Violet, Melachite crystal Voilet- target gram +ve bacteria, but
action affected in presence of organic compounds.
ACRIDINE e.g, Acriflavin, Euflavin, Proflavin, Interrupt Proteins and DNA synthesis
9.GASEOUS STERILIZATION: e.g, ET.O Ethylene Oxide,Can kill all of bacteria
vegetative body & Spores, but is Highly inflammable, irritant, explosive and carcinogenic.
Used to sterlize only plastic equipment, Respiratory and Dental utensils
MECHANICAL STERILIZATION METHODS
FILTRATION: used to sterlize liquid and gas material, which are heat labile and can’t be sterlized by
Chemical sterlizants.
Depth Filter: Retains microbes throughout the depth of filter rather than on Surface. Used to purify Air
and Water.
Membrane Filter: Retain microbes larger than the pore size on the
Surface. Used to sterlize Bacteriophage, Toxins, Virus, Suger and
Antibiotics Solution.

14. The End