DISINFECTION.pptx

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.

1. DISINFECTION Prepared by- Arpita C handra

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 10 3 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.

4. Including disinfectant Alcohol Aldehydes Phenols Halogens Oxidizing agents Salts Surface Active Agents Dyes Gases

5. Classification of disinfectants

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 , H ydrogen peroxide, P eracetic acid and C hlorine 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, I odophores & P henolic 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

10. Methyl alcohol Effective against fungal spores and used for treating cabinets affected by them,vapour is toxic and inflammable.

11. ALDEHYDES 1.Formaldehyde 2.Glutaraldehyde 3.Ortho-phthaldehyde

12. Formaldehyde (CH2O) B actericidal, sporicidal & virucidal , U sed 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 – Preservative of tissue for histological examination. To sterilize bacterial vaccines . To prepare toxoid from toxins. For killing of bacterial cultures and suspensions. 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 . S terilant 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 ”.

14. 1.Cidex solution with 2% glutaraldehyde . 2.bacillocid for OT surface cleaning.

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 A s 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.

19. 1.Savlon ( chlorhexidine & cetrimide solution) 2.microsheild (4% chlorhexidine handwash )

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

23. Sodium hypochlorite solution(5%)

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% K ills 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 s terilizing 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 Aniline 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 E uflavine P roflavine Aminacrine Affected very little by the presence of organic material D o not use as selective as the aniline dyes Interfere, synthesis of nucleic acids & proteins in bacterial cells.

35. 9.gases Ehthylene oxide gas Formaldehyde gas Betapropiolactone (BPL)

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-

37. three working stages- 1.Preconditioning- -Air is removed from the chamber ,leakage test performed - Temperature,pressure and humidity will be set in chamber.

38. 2. S terilization- 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)

41. Sterilization control- Spores of Bacillus atrophaeus as biological indicator Uses-

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.

43. Testing of disinfectants- Rideal Walker test Chick Martin test Kelsey-Sykes test In-use tests

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.

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