2. HISTORY OF STERILIZATION IN BRIEF:
• LOUIS PASTEUR: Father of microbiology.
Introduced steam sterilizer, hot air oven and autoclave.
• JOSEPH LISTER: Applied Pasteur’s work and introduced
antiseptic technique in surgery(1867)
He is the father of antiseptic surgery.
• SEMMELWEISS AND HOLEMEUS: First recognized importance
of hand washing in reducing infection.
3. DEFINATIONS:
• STERILIZATION: It is a process by which all living organisms including viable
spores are either destroyed or removed from an article, body surface or
medium.
The agents which achieve sterilization are called as sterilants.
• DISINFECTION: It refers to a process that destroys or removes most of
pathogenic organisms but not the spores.
• ASEPSIS: The term used to indicate the prevention of infection usually by
inhibiting the growth of bacteria in wounds or tissue.
• ANTISEPTICS: Are chemical disinfectants that can be safely applied on the skin
or mucous membrane & are used to prevent infection by inhibiting the growth
of bacteria.
• BACTERICIDAL AGENTS: Are those that can kill bacteria.
• BACTERIOSTATIC AGENTS: Prevent the multiplication of bactereia which may
however remain alive.
5. Level of risk Application Process Storage Example
Critical Entry into
sterile
tissue(blood
stream,cavit
y)
Autoclave if
Heat stable &
ETO or H2O2
Gas plasma if
heat sensitive
Sterility must be
maintained.
Dry items before
removal from
steriliser.
Wrapper should be
intact
Needles, invasive
instruments,
laparoscopes, cardiac
catheters.
Semi-critical Contact with
intact
mucosa(non
-intact skin)
Autoclave
If heat
intolerant,then
chemical
disinfection by
gluteraldehyde
Protect from
environmental
contamination
Endoscopes, proctosope,
urinary catheters
Non-critical Contact with
skin
Detergent(clean)
+ water
Disinfect with
70%alcohol
Store in a clean dry
place
Stethoscopes,
sphygmomanometer,
cardiac electrodes, bed
pans
Spaulding’s classification of Medical devices
6. CLASSIFICATION OF STERILIZATION:
STERILIZATION
CHEMICAL
METHODS
PHYSICAL
METHODS
i) Sunlight
ii) Drying
iii) Dry heat: flaming, incineration, hot air
oven
iv) Moist heat: pasteurization, boiling, steam
under normal pressure, steam under
pressure
v) Filtration: candles, asbestos pads,
membranes
vi) Radiation: ionizing, non ionizing.
vii) Ultrasonic and sonic vibrations
i) Alcohol: ethyl, isopropyl, trichorobutanol
ii) Aldehydes: formaldehyde, glutaraldehyde
iii) Dyes
iv) Halogens
v) Phenols
vi) Surface active agents
vii) Metalic salts
viii) Gases: ethylene oxide, formaldehyde, beta
propiolactone, hydrogen peroxide fogging, plasma
sterilizer.
7. FACTORS INFLUENCING EFFICACY OF STERILANT/ DISINFECTANT:
1) Organism load
2) Nature of organism
3) Concentration of sterilant
4) Contact time
5) Temperature
6) Stability
7) Local pH
8) Relative humidity
9) Organic matter
10) Biofilm formation
9. PROPERTIES OF IDEAL STERILANT:
• Broader microbial activity
• Fast acting
• Not affected by environmental factors
• Non toxic
• Compatible with surface or material
• Odourless / pleasant odour
• Economical
• Environmental friendly.
10. (A)ALCOHOL:
1) ETHYL ALCOHOL AND ISOPROPYL ALCOHOL:
MOA-
Act by denaturing
bacterial proteins bacterial protens.
11. • No action on spores
• Concentration 60-90% in water to be effective.
• Protein slows its action & mineral acids or alkalis enhances its action.
• Mainly used as skin antiseptics.
• Isopropyl alcohol: better fat solvent, more bactericidal, less volatile.
• Used for disinfecting clinical thermometers.
• Sterilium is used for hand hygiene
2) METHYL ALCOHOL:
• Effective against fungal spores and is used
for treating cabinets and incubators
affected by them.
• Methyl alcohol vapours are toxic and
inflammable.
12. (B) ALDEHYDES:
1) FORMALDEHYDE:
MOA: Active against the amino group in the
protein molecule .
USES: - Bactericidal, sporicidal, lethal effect on
viruses.
- Used to preserve anatomical specimen.
- for destroying anthrax spores in hair and wool.
- 10% formalin and 0.5% sodium tetraborate is used to
sterilise clean metal instruments.
13. 2) GLUTARALDEHYDE
• Trade names: Cidex, Sonacide, Sporicidin, Hospex.
• Concentration: 2-3% -is active against a wide range of microorganisms.
• MOA:
Causes Alkylation of sulfhydryl, hydroxyl, carboxyl, and amino groups of
organism
ALters RNA, DNA, and protein synthesis.
• Used to sterilize a variety of heat sensitive instruments viz. endoscopes,
bronchoscopes, dialysis equipment, anesthesia & respiratory equipment,
transducers & spirometry apparatus.
• Spectrum of activity:Active against MRS,VRE, Influenza A virus, E.coli,
Salmonella typhi, P.aeruginosa, Klebsiella, Avian rotavirus.
• 2% cidex in our hospital is used in serology and virology for decontamination
of ELISA wells, rapid test kits, microtips, etc.
14. • Use and handling:
- While transferring, pour the liquids carefully and minimize splashing
- Rinse soaked instruments under running water.
- Use adequate ventilation.
- Use protective equipments: Gloves, Glasses, gas masks, etc.
• Transportation and storage:
- Should be done in closed containers with tight
fitting lids that it will not spill.
- Store in a cool area and lebel it properly.
- Dispose off outdated solutions properly.
15. ADVANTAGE DISADVANTAGE
• Biodegradable
• Non carcinogenic (unlike
formaldehyde)
• Non corrosive to metals,
rubbers, plastics
• Relatively inexpensive
• Excellent material compatibility
• Side effects due to
glutaraldehyde vapours:
Respiratory and dermal irritant,
occupational asthma, itching of
eyes, rhinitis.
• Pungent & irritating odour
• Slower mycobacterial activity as
compared to OPA
GLUTERALDEHYDE
16. ADVANTAGES DISADVANTAGES
• Active against glutaraldehyde
resistant Mycobacterium
• Non-irritant to the eyes and
nasal passages
• Has excellent stability over a
wide range of pH (pH 3-9)
• Does not require exposure
monitoring, and has a bareable
odour
• OPA has excellent material
compatibility
• OPA stains proteins gray
(including unprotected skin) so
must be handled with caution
(i.e., use of gloves, eye
protection, fluid-resistant
gowns).
3) ORTHO-PHTHALDEHYDE (OPA):
• MOA: similar to glutaraldehyde.
17. (C) DYES:
1) ANILINE DYES: Brilliant green, malachite green, crystal violet
MOA: They react with the acid groups in
bacterial cells.
USES: - Skin and wound antiseptic
- more active against gram positive
organisms than gram negative .
- Have no activity against tubercle bacilli
hence malachite green used in LJ
medium.
- Used as selective agent in culture
media.
18. 2) ACRIDINE DYES: Proflavin, euflavin, acriflavine, aminacrine.
MOA: They impair the DNA complexes of
organism kill or destroy the
reproductive capacity of bacterial cell.
- They are very little affected by presence of
organic matter.
- More active against gram positive than gram
negative organisms.
- Impregnate them in gauze they are slowly
released in a moist environment .
19. (D) HALOGENS:
1) IODINE:
MOA: Iodine rapidly penetrates into microorganism
Oxidizes proteins, nucleotides & fatty acids
Causes Cell death
USES: - Skin disinfectant
- Actively bactericidal with moderate action against spores
- Active against tubercle bacilli and viruses.
Iodophores- Compounds of iodine with surface active
agents.
- More active.
20. 2) CHLORINE:
Active as hypochlorous acid ( HOCl)
and hypochlorite ion (OCl- )
• MOA: Break the chemical bond in the molecules on membrane
Rupture of membrane
Loss of permeability and coagulation of cytoplasm.
• USES: - wide spectrum of action against viruses
- Organic chloramines are used as antiseptic
for dressing wounds.
- As disinfectant in water supplies, swimming
pools, dairy & food industry
- 10% Sodium hypochlorite used in spill management
in hospitals.
21. 3) CHLORINE DIOXIDE(CIO₂)
• Prepared by reacting Hypochlorus acid and sodium or potassium chlorate.
• MOA: It is a free radical and disinfects by oxidation
Organic materials in bacterial cells react with chlorine dioxide Interruption
in cellular processes.
Chlorine dioxide reacts directly with amino acids and the RNA in cell
Proteins synthesis is blocked
Cell death
• USES:
- Drinking water disinfection.
- Can be used against anthrax (ClO2 is effective against spore forming bacteria)
22. ADVANTAGES DISADVANTAGES
• Better disinfectant activity than
chlorine.
• Deactivates chlorine resistant
Giardia and Cryptosporidium.
• Low contact time required
• Explosive.
• Safety equipment must be used
while handling as it causes
irritation,watery eyes.
• Highly unstable when in contact
with sunlight.
• More expensive than chlorine.
CHLORINE DIOXIDE
23. (E) PHENOLS:
- Obtained by distillation of coal tar between temperature
of 170 to 270 degree C.
- Lister, the father of antiseptic surgery first introduced
them in surgery (1865)
- MOA: Cell membrane damage
Releasing cell content
Lysis of cell.
- Low concentration of phenols precipitate proteins.
24. USES:
- Lysol and cresol active against wide range of organisms.
- They are not much affected by presence of organic matter. Good general
disinfectant.
- They are used in control of pyogenic cocci in surgical and neonatal units in
hospitals in different combinations.
- Aqueous solutions are used in treatment of wounds.
25. (F) SURFACINE:
• Surfacine is a surface coating that kills microorganism contact, by selectively
delivering Silver.
• Used on animate or inanimate surfaces.
• Silver has a broad spectrum of activity (bacteria, yeast and fungi)
CAN BE USED IN:
• Medical devices: prostheses, catheters, endotracheal tubes etc.
• Dental care products.
• Water storage, treatment and delivery systems.
• Antimicrobial effect remains for 13 days.
26. The object to be disinfected is
sprayed,dipped or brushed with surfacine.
silver-iodide(water insoluble) compound incorporate
in Polyhexamethylenebiguanide on surface coating
microorganisms contacting the coating accumulate
silver until the toxicity threshold is exceeded.
dead microorganism lyse and detach from the surface.
SURFACINE MOA:
27. ADVANTAGES:
• Very low leaching of silver into solutions.
• Duration of activity: Long term.
• Reservoir capacity: High.
• Non toxic to humans
DISADVANTAGE:
Not active against viruses and very less activity
against spores.
28. (G) SUPEROXIDIZED WATER: (STERILOX/MEDILOX)
• Broad spectrum disinfectant, introduced recently.
• Prepared by electrolyzing saline solution with titanium coated electrodes. The
main products are Hypochlorous acid[HCIO] as well as free chlorine radicals &
superoxide radicals
• MOA is not clear but probably relates to a mixture of oxidizing species.
• Applications: Freshly generated superoxidized water is rapidly effective
(<2minutes) against microorganisms (Mycobacterium tuberculosis, M.
chelonae, poliovirus, HIV, MRSA, E.coli, Candida albicans, Enterococcus faecalis,
Pseudomonas aeruginosa)
• Advantages:-Basic materials i.e saline and electricity, are cheap & the end
product (water) is not damaging to the environment.
- Nontoxic to Humans
• Disadvantage: Equipment used to produce the product may be expensive
29. (H) ENDOCLENS :
• Used for sterilization of flexible endoscopes.
• Consists of a computer-controlled endoscope reprocessing machine that uses
performic acid as a sterilant.
• Performic acid is produced by mixing of the two component solutions of
hydrogen peroxide and formic acid
Endoscope
30. • WORKING- during washing enzymatic detergent is automatically dispense,
diluted with warm water and sprayed on and into endoscope
• ADVANTAGES
- Automatic
- Rinsing and drying done after sterilization
- Total cycle time less than 30 minutes
31. (I) PERACETIC ACID:
• Rapid action against all microbes
• Remains effective in the presence of organic matter
• MOA: Denatures proteins
Disrupt cell wall , permeability
Oxidizes sulfhydryl and sulfur bonds in
proteins and other enzymes.
32. ADVANTAGES DISADVANTAGES
• Rapid cycle time (30-45 min)
• Environmental friendly by-
products (acetic acid, O2, H2O)
• No adverse health effects to
operators under normal
operating conditions
• Compatible
• Does not coagulate blood or fix
tissues to surfaces
• Sterilant flows through scope
facilitating salt, protein, and
microbe removal
• Rapidly sporicidal
• One scope or a small number of
instruments can be processed
in a cycle
• More expensive (endoscope
repairs, operating costs,
purchase costs) than high-level
disinfection
• Serious eye and skin damage
(concentrated solution) with
contact
• No long-term storage
33. (J) QUATERNARY AMMONIUM COMPOUNDS:
• MOA:
- Inactivation of energy-producing enzymes
- Denaturation of essential cell proteins
- Disruption of the cell membrane
• USES:
- They are commonly used in ordinary environmental sanitation of noncritical
surfaces, such as floors, furniture, and walls.
- For disinfecting medical equipment that contacts intact skin (e.g., blood
pressure cuffs).
