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STERILISATION - 3

STERILISATION - 3. DR SATHYA ANANDAM. FILTRATION. Removal of microbes by passage of a liquid or gas through a screen like material with small pores. Heat sensitive materials like vaccines, enzymes, antibiotics, and some culture media.

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STERILISATION - 3

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  1. STERILISATION - 3 DR SATHYA ANANDAM

  2. FILTRATION • Removal of microbes by passage of a liquid or gas through a screen like material with small pores. • Heat sensitive materials like vaccines, enzymes, antibiotics, and some culture media. • As viruses pass through ordinary filter, filtration used to obtain bacteria-free filtrates for virus isolation. • concentrate bacteria from liquids as for example in testing water samples for cholera vibrios or typhoid. • Bacterial toxins obtained by passing through filters.

  3. Types of Filtration • Candle filters- Unglazed ceramic eg. Chamberland,Doulton. Diatomaceous earth eg. Berkefeld, Mandler • Asbestos filters- disposable discs eg. Seitz, Sterimat • Sintered glass filters • Membrane filters– cellulose esters, polymers • High Efficiency Particulate Air Filters

  4. FILTERSCandle filter Seitz filter sintered glass filter

  5. Candle filters • For purification of water for industrial &drinking purpose . • a)unglazed ceramic filters -Chamberland &Doulton filters . • b)Diatomaceous earth filters : Berkefeld& Mandler filters . • Sterilized by Hypochlorite solution . • Not withstand for scrubbing

  6. CHAMBERLAND FILTER

  7. DOULTON FILTER

  8. Asbestos filters • Disposable ,single use type . • High adsorbing capacity ,Tend to alkalize the fluid • carcinogenic potential • Eg ;seitz &Sterimatfilters • seitz : Chrysotile type of Asbestos. (Magnesium silicate). • This filter disc is supported on metal mount and filter is attached to a vacuum flask. • This is sterilized by autoclave

  9. SEITZ-FILTER

  10. Sintered glass filters • Sintered glass filters : By heat fusing finely powdered glass particles of diff grades . • low absorptive capacity ,cleaned easily . • brittle &Expensive .

  11. Membrane filters • 0.2 - 0.22 micron for sterilization • composed of cellulose esters or other polymeric materials • filter material must be compatible with liquid being filtered • used in water purification and analysis ,sterilisation & sterility testing • for preparation of solutions for parenteral use & in industry & research.

  12. Filtration assembly

  13. High Efficiency Particulate Air Filters (HEPA) • Used in operating rooms and burn units to remove bacteria from air • unable to remove viruses and some small bacteria (mycoplasma)

  14. HEPA filter

  15. Forms of Radiation

  16. RADIATION • Two types -1.Ionising . 2.Non –ionising . • Ionisingtype –X-rays ,gamma rays ,cosmic rays .No rise in the temperature –cold sterilisation . • Non –ionising type :Infrared & ultra violet rays. Hot air sterilisation.

  17. Non-Ionizing Radiation Low energy, non- ionizing, low penetrating power electromagnetic rays. Rays are absorbed as heat on the surface of an article. Hot air sterilization. Types of rays used for this purpose are: A. Infrared rays B. UV rays

  18. Penetration power is poor • Irritation of eye and skin Lethal effects: 1. Denaturation of proteins. 2. Damage to DNA. 3. Inhibition of DNA replication.

  19. Uses: 1. Mass sterilization of syringes. 2. Entryways. 3. Hospital wards. 4. Small inoculating cabinets. 5. Piped-water supplies. Draw backs: 1. Sterilize only surfaces . 2. Retinal damage to operator.

  20. Ionizing radiation (Cold sterilization) • Gamma rays generated by Cobalt 60 • Rays with high penetrating power like X-rays, gamma - rays, cosmic rays. Highly lethal to DNA. • Uses:Disposable syringes, Culture plates, Catheters, Animal feeds, Surgical catgut, Bone and tissue grafts. • Disadvantages: Penetrates human tissues. May cause genetic mutations.

  21. ULTRASONIC AND SONIC VIBRATIONS Ultrasonic and Sonic waves are used. Results are variable. Bactericidal No practical value in sterilization and disinfection.

  22. Methods of sterilization (I) Not for virus

  23. CHEMICAL AGENTS( DISINFECTANTS & ASEPTICS)

  24. Chemical Methods 1. Phenols and Phenolics2. Halogens 3. Alcohols 4. Heavy Metals 5. Surface active agents 6. Aldehydes 7. Gaseous Sterilizers 8. Peroxygens (Oxidizing Agents) 9. Dyes

  25. CHEMICAL AGENTS • Include : 1.Anti septics . 2.Disinfectants . • Criteria for a ideal chemical agent : • have a wide spectrum of activity . • active in presence of organic matter . • effective in acid &alkaline media . • speedy action &high penetrating power . • stable ,not corrode metals . • not cause local irritation ,sensitisation . • not toxic ,not interfere with healing . • easily available ,safe &easy to use .

  26. CHEMICAL DISINFECTANTS .

  27. CHEMICAL AGENTS • DETERMINANTS OF DISINFECTANT POTENCY - Concentration - Time of action - pH of medium - Temperature - Nature of organisms - Presence of extraneous material • ACTION - Protein coagulation - Cell membrane disruption - Removal of sulphydryl groups - Substrate competition

  28. ALCOHOLS • Methyl alcohol, Ethyl alcohol, Isopropyl alcohol - Most widely used • Concentration to be used is 70 - 90% in water. • Rapidly –1. Bactericidal .(opt concn-60-70%) 2.tuberculocidal . 3. Virucidal. 4. Fungicidal . • Not sporicidal • Isopropyl alcohol: Better.

  29. Uses :1. Skin disinfectant (Ethyl alcohol). 2. Disinfection of clinical thermometers (Isopropyl Alcohol). 3. Treating small cabinets, incubators (Methyl alcohol) 4. External surfaces of equipments

  30. Disadvantages: • Vapors are toxic and inflammable (Methyl Alcohol) have to be stored in cool & well ventilated place • Limited action on Mycobacteriae • Poor action in the presence of blood & organic matter • Evaporate rapidly

  31. ALDEHYDES • Formaldehyde: • Active against amino group in protein molecule. • Bactericidal, tuberculocidal ,fungicidalSporicidal and viricidal. • Available and gaseous forms. • 10% formalin as aqueous preparation.

  32. Uses : • To preserve anatomical specimens. • To destroy anthrax spores in hair and wool. • 10% formalin + 0.5% sodium tetra borate sterilize clean metal instruments in dentistry. • To prepare toxoidsfrom toxin • Formaldehyde gas –sterilising instruments & catheters . • Fumigating sick rooms ,wards ,laboratories.

  33. Disadvantage: • Toxic and irritants when inhaled • Potentially carcinogenic

  34. Gluteraldehyde • High-grade disinfectant. • Specially effective against TB bacilli, fungi and viruses. • Available as 2% buffered solution ( Cidex) • Active in presence of organic matter . • No deleterious effect on cementing substance of lenses

  35. Uses : Sterilization of Cystoscopes. Bronchoscopes. Anesthetic tubes. Plastic endotracheal tubes rubber anesthetic masks ,rubber tubes. Polythene tubes Metal instuments

  36. DYES • Skin & wound antiseptics • Low bactericidal activity • Aniline dyes – brilliant green, Crystal violet • Acridine dyes – Proflavine, acriflavine

  37. Aniline dyes • Reacts with acid groupsin cells. • Ineffective in the presence of organic matter like pus. • Active against Gram positive than Gram negative bacteria. • Ex: Brilliant green. Crystal violet. Malachite green.

  38. Acridine dyes More active against Gram positive bacteria. Impairs the DNA complexes in microbes. Ex:Proflavine Acriflavine Enflavine Aminacrine Efficacy affected very little in the presence of organic matter.

  39. Uses :1.Skin and wound antiseptics. Impregnated gauge: Wound debridement. 2. Selective agents in culture media(Malachite green in L.J medium ) Advantages : Non irritant and nontoxic to skin and mucus membranes.

  40. Halogens A.Iodine: Tincture of iodine (alcohol solution) was one of first antiseptics used. Combination of iodine in aqueous & alcoholic solutions. • Combines with amino acid tyrosine in proteins & denatures proteins. • Stains skin and clothes. Actively bactericidal, active against tubercle bacteria & viruses, with moderate action against spores

  41. Iodophors • Compounds of iodine with nonionic wetting or surface active agents. • Slow releasing, take several min to act. • Used as skin antiseptic in surgery, hand disinfectant. • Disinfection of blood culture bottles & medical equipments such as hydrotherapy tanks, thermometers & endoscopes. • Not effective against bacterial endospores. • Eg. Betadine & Isodine

  42. Chlorine • When mixed in water forms hypochlorousacid: Cl2 + H2O ------>H+ + Cl- + HOCl(Hypochlorousacid) • Used to disinfect drinking water, pools, sewage, food & dairy industry . • Chlorine & hypochlorites markedly bactericidal & wide spectrum of action against viruses. • Inorganic chlorine solution used for disinfecting tonometer heads & for spot disinfection of countertops & floors • Chlorine is easily inactivated by organic materials. • Alcohol based formulations of chlorine like Chlorhexidine is Good choice for hand disinfection

  43. Chlorine • Sodium hypochlorite (NaOCl): Is active ingredient of bleach. • Chloramines: Consist of chlorine & ammonia. Used as antiseptic for dressing wounds. Less effective as germicides. • Calcium hypochlorite, sodium dichloroisocyanurate – solid form, microbicidal activity greater than liquid form. • Chlorine compounds may damage material like plastic, rubber, some metals & fabrics. • When hypochlorite come in contact with formaldehyde, carcinogen bischloromethyl ether is formed.

  44. Uses : 1. For swabbing the local parts prior to any procedure. 2. Iodine preparations active against TB, bacilli ,viruses. 3. Water supplies, swimming pools. 4. Food and dairy industry (Chlorine) 5. For dressing of the wounds. 6. Cleaning & Debridement of wounds.

  45. Advantages : Broad spectrum of activity • Fast acting • Inexpensive • Limitations : unstable ,corrosiveness • Used to disinfect –swimming pools ,water suppliers ,food&dairy industries

  46. JOSEPH LISTER

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