Above ppt includes different types of disinfectants used in microbiology ,classification of disinfectants, and also it includes some important techniques like Plasma sterilization ,ETO sterilization and bleaching of water.
2. INTRODUCTION
Disinfection-
It means the destruction of all pathogens or
organism capable of producing infection but not
bacteria spores.
It results in reduction of at least 103 log colony
forming units of microorganism but not spores
Primary goal in disinfection is to destroy potential
pathogens.
It also substantially reduces the total microbial
population.
3. FACTOR INFLUENCE THE POTENCY OF A DISINFECTANTS -
Concentration
Time of action
pH
Temperature
Nature of organism
Presence of organic matter.
6. HIGH LEVEL DISINFECTANTS
Effectiveness of high level disinfectants may be
equivalent to that of sterilization .
These disinfectants are used for certain types of
endoscope, cystoscopes & surgical
instruments with plastic components,
INCLUDE –
Glutaraldehyde,
Hydrogen peroxide,
Peracetic acid and
Chlorine compounds.
7. INTERMEDIATE LEVEL DISINFECTANTS
It may not be effective against bacterial spores,
These disinfectants are used for instruments (e.g.-
laryngoscopes, fiberoptic endoscopes) where
contamination with spores and other highly
resistant organism is unlikely.
INCLUDE-
Alcohols,
Iodophores &
Phenolic compounds.
8. LOW LEVEL DISINFECTANTS
Many organisms can survive on exposure to low
level disinfectants.
Used for items which come in contact with the
patients but they do not penetrate into tissue.
Example- Stethoscope, electrocardiogram
electrodes etc.
9. ALCOHOLS
Ethyl alcohol and isopropyl alcohol are the most
frequently used.
-Used as surgical spirit,hand rubs & antiseptics.
-Act by denaturing bacterial proteins,
-Kill bacteria including tubercle bacilli but no
sporicidal or virucidal activity.
-HIV is susceptible to 70% ethyl alcohol and & 35%
isopropyl alcohol in the absence of organic matter.
-Used mainly as skin antiseptics.
-should be Used at a concentration of 60-70% in water
12. FORMALDEHYDE (CH2O)
Bactericidal, sporicidal & virucidal,
Used both as aqueous solution and in gaseous form
A 10% aqueous solution of formalin is routinely used
Active against amino group in the protein molecule.
Uses –
a) Preservative of tissue for histological examination.
b) To sterilize bacterial vaccines.
c) To prepare toxoid from toxins.
d) For killing of bacterial cultures and suspensions.
e) For destroying anthrax spores.
13. GLUTARALDEHYDE
Effective against bacterial (M. tuberculosis),
fungi and viruses (HIV, Hepatitis B virus and
enteroviruses ).
Also kills spores
Less toxic and irritant to the eyes and skin than
formaldehyde.
Sterilant and high level disinfectant
Does not damage plastics ,act in the presence of
organic matter,
Used as 2% buffered solution
Available commercially as “cidex” & “Bacillocid”.
15. USES OF GLUTARALDEHYDE-
Sterilization of cystoscope,endoscope &
bronchoscope.
Sterilize plastic endocardial tubes,face masks,
corrugated rubber anaesthetic tubes and metal
instruments.
16. ORTHO-PHTHALALDEHYDE
High level disinfectant
0.5% OPA is sporicidal
Vapours may irritate the respiratory tract & eyes
More rapidly mycobactericidal than glutaraldehyde
17. PHENOLS
First introduced by Lister (father of antiseptic surgery)
As carbolic acid spray on surgery(1867)
Phenols are produced by distillation of coal tar between
temperatures of 170°C & 270°C.
Causes bacterial cell damage, releasing cell contents &
causing lysis.
Phenol(1%) has bactericidal action
As antiseptics- cresols, chlorhexidine, chloroxylenol,
Hexachlorophane
18. 1. CRESOLS
Used as disinfectant in laboratories and hospitals.
Lysol is a solution of cresols in soap.
Most commonly used for infected glasswares, cleaning
floors.
2.Chlorhexidine-
Savlon (chlorhexidine and cetrimide)
Used in wounds,pre-operative disinfection of skin etc.
More active against gram+ve and gram-ve bacteria
No action against tubercle bacilli or spores
Very little activity against viruses .
Good fungicidal activity.
20. 3.CHLOROXYLENOL
It is an active ingredient of dettol.
Less toxic and less irritant
Readily inactivated by presence of organic matter
Inactive against pseudomonas.
21. 4. HEXACHLOROPHANE
More active against gram +ve than gram-ve
bacteria
Applied on skin as prophylaxis against
staphylococcal infection,
It can cause brain damage ,hence its use as
antiseptic is restricted.
22. HALOGENS
Chlorine(Cl) and iodine(I) commonly used
Bactericidal and are effective against sporing
bacteria and virus
CHLORINE- (0.2-1 mg/l)
Used in water supplies
Swimming pools ,food and dairy industries.
In the form of bleaching powder,sodium
hypochlorite and chloramine are also used
24. IODINE-
In alcoholic and aqueous solution is used as a skin
disinfectant
Actively bactericidal,with moderate action against spores
It also inactivated by organic matter
Iodine with surface active agents known as iodophores, more
active,
Betadine(10%) is one
example of commonly used iodophores.
25. 5. OXIDIZING AGENTS
-Hydrogen peroxide(H2O2)
Used for high level disinfection & sterilization,
Effective against most organisms at concentration of 3-6%
Kills all organism including spores at higher concentration
(10-25%)
Libration of free hydroxyl radical on decomposition of H2O2
H2O2 is used to disinfect contact lenses,surgical prostheses
& implants.
26. -Peracetic acid
An oxidizing agent
High level disinfection
Effective in the presence of organic matter
More potent germicidal agent than hydrogen
peroxide
Uses-
To disinfect hemodialyzer and
Also use for sterilizing endoscopes
27. -PLASMA STERILIZATION
Recently introduced sterilization method.
Principle:-
-It refers to a gaseous state consisting of ions, photons and
free electrons and neutral uncharged particles(such as O
and OH)
-Active agents present in plasma such as photons of UV
rays and radicals are capable of killing microbes and
spores efficiently.
28. -Mixture of H2O2 and peracetic acid are used which
provide O and OH.
-Low temperature is maintained (37-44°C)
-Preserves the integrity of heat labile items
-1 hour- cycle duration
-2 commercial plasma sterilizers available are Sterrad
100S sterilizer & plazlyte sterilizer.
29. USES-
Sterilization of materials and devices that can not
tolerate high temperature and humidity of
autoclave,
Such as some plastic, electrical devices, and
corrosion-susceptible metal alloys.
Sterilization control- tested using Geobacillus
stearothermophilus.
30. 6. HEAVY METAL SALTS
Salt of copper ,silver and mercury are used as
disinfectant
They are protein coagulants
Combining with sulphydryl (SH) groups of bacterial
proteins and other essential interacellulr compounds
Mercuric chloride, thiomersal and mercurochrome
were known antiseptic and antifungal agents ,but are not
used nowadays due to their toxicity.
Copper salts are fungicides.
31. 7. SURFACE ACTIVE AGENTS-
These substances producing a reduction of surface
tension are known as surface active agents
They are classified- anionic, cationic, nonionic and
amphoteric compounds.
Surfactants may act as detergents,wetting agents
and emulsifiers.
Gram +ve species species are more susceptible
No action on spores and tubercle bacilli
Active against viruses with lipid envelopes
32. Cationic compounds
- Acetyl trimethyl ammonium bromide and benzalkonium
chloride.
- More active at an alkaline pH.
Anionic compounds
- Common soaps, have strong detergent but weak
antimicrobial properties,
- Most active at acidic pH,
- More Effective against gram positive organism.
Amphoteric surfactants
-They possess detergent properties of anionic
compounds and antimicrobial activity of cationic
compounds.
Ex- Tego compounds
33. 8.DYES
1. Aniline
2. Acridine dyes
used extensively as skin & wound antiseptics.
Aniline Dyes- Crystal violet,
Gentian violet,
Brilliant green and
Malachite green.
-non toxic ,non irritant
-more active against gram +ve than gram –ve.
-No activity against M. tuberculosis
-As selective agents on culture media (Malachite
green in Lowenstein-jensen medium.
34. Acridine dyes -
Include- Acriflavine
Euflavine
Proflavine
Aminacrine
Affected very little by the presence of organic material
Do not use as selective as the aniline dyes
Interfere, synthesis of nucleic acids & proteins in
bacterial cells.
36. ETHYLENE OXIDE GAS
Widely used gaseous chemical sterilants in present
days
Microcidal and sporocidal both
Special equipment used Ethylene oxide sterilizer
ETHYLENE OXIDE STERILIZER-
38. 2. Sterilization-
- Gas allowed to enter the chamber
- EtO concentration- 700mg/L
- 40-80% humidity
- Sterilization is achieved in 4-5 hours at 38°C or 1
hour at 55°C.
39. 3. Aeration –
Aeration of sterilized materials for 8-12 hrs necessary
to remove residual EtO.
40. ADVANTAGES-
More chamber capacity
Low temperature
Highly diffusible
Penerates area that cannot be reached by steam
Non corrosive to plastic ,metal & rubber materials
Disadvantages-
Highly inflammable
Irritant,explsive and carcinogenic
Long duration of cycle(12-14hrs)
42. 2. FORMALDEHYDE GAS-
Used for fumigation of operation theaters,wards
,laboratories.
However this method is no longer preferred
Formaldehyde gas is generated by adding 150g of
KMnO4 to 280ml formalin for every 1000cu. Feet
of room volume
Room should be sealed for 48hrs.
3.Betapropiolactone-
-BPL Gas 0.2% is active against all microbes
including spores
-Used for inactivation of vaccines.
44. 1. RIDEAL WALKER TEST
Suspensions containing similar quantities of
organisms are submitted to the action of varying
concentration of phenol & of the disinfectant to be
tested
Dilution of the test disinfection which sterilizes the
suspension in a given time is devided by the
corresponding dilution of phenol,
This gives the phenol coefficient =1
Higher the phenol coefficient ,more effective is the
disnfection.
45. 2.CHICK MARTIN TEST-
Modification of Rideal Walker Method
Is done conditions mimicking naturality i.e, in the
presence of organic matter
3% dried human feces is a added
Contact time is increased to 30min.
Both S. typhi & St.aureus are used for testing
efficacy.
46. 3.KELSEY-SYKES TEST
Also called capacity use dilution test
Triple challenge test
Designed to determined concentration of
disinfectant that will be effective in clean and dirty
conditions.
Duration of test -30min
47. IN USE TESTS-
A new disinfectant is determined by its ability to
inactivate a known number of a standard strain of a
pathogenic staphylococcus on a given surface
within a certain time.