9/20/2011
1
Kher
Learning Objectives Compare and contrast the processes of sterilization disinfection and antisepsis State principle of sterilization Describe methods used in sterilization List agents and equipments commonly used in sterilization List applications of sterilization Describe quality monitoring of sterilization Resource - Ananthanarayan Ch 3
9/20/2011
2
Kher
Why do we need to sterilize? Briefly,
to get rid of microbes! Application in Microbiology Surgery Food, drug industries Many other situations
9/20/2011
3
Kher
What is Sterilization, Disinfection & Antisepsis? Sterilization
: Process by which an article, surface or medium is freed of all organisms. Disinfection : Destruction of all pathogenic organisms or organisms capable of giving rise to infection. Antisepsis : Prevention of infection usually by inhibiting growth of bacteria. Bactericidal & Bacteriostatic agents 9/20/2011
4
Kher
Classification PHYSICAL Sunlight Drying Heat Dry Moist Filtration UV & Sonic waves Radiations
9/20/2011
5
Kher
CHEMICAL Alcohols Aldehydes Gases Heavy Metal Salts Halogens Dyes Surfactants Phenols
Heat : The most reliable method of choice, Unless contraindicated! Factors
influencing – Nature of heat – dry or moist Temperature & time Lower temp with longer duration or repeat cycle
No. of microbes present Types of microbes Type of material to be sterilized 9/20/2011
6
Kher
Dry Heat : And Dry heat maintains sterility longer!! Mechanism Methods
9/20/2011
: Oxidative destruction
:
Flaming : Slides. Scalpels, Needles. Cover-slips Red Heat : Inoculating Loops, Points of Forceps Incineration : Rapid & terminal destruction of soiled material Hot Air Oven 7
Kher
Incinerator
9/20/2011
8
Kher
Hot Air Oven Structure
Holding Time – 160 C X 60 Min Use – Metal, Glass articles, Fats, Oils Greases, Talc & Sulpha powders Not Sterilized – Glass+Metal articles, Culture media Precautions :
9/20/2011
Ensure load dried, No overloading, Proper packing, Open only after cooling 9
Kher
Hot air oven
9/20/2011
10
Kher
Moist Heat
Latent heat makes all the difference! Latent Heat :1600 ml of steam condenses to one ml of water releasing 518 calories of heat Classification :
Temp below 100 C
Temp at 100 C
Boiling Koch’s steam sterilizer
Temp above 100 C
9/20/2011
Pasteurization Vaccine bath Inspissation
11
Autoclave
Kher
Temp below 100 C Pasteurization
9/20/2011
:
Holder – 63 C x 30 min Flash – 72 C x 20 sec followed by rapid cooling to 12 C For milk & milk products
12
Kher
Vaccine
bath :
For pure cultures only 60 C x 30 minutes
Inspissation
:
85 C x 30 min x 3 successive days Egg & Serum containing media
9/20/2011
13
Kher
Temp at 100 C Boiling
At best method of disinfection For instruments used on body surface
Koch’s
9/20/2011
:
steam sterilizer :
100 C x 20 minutes x 3 successive days For sterilization of sugar containing media
14
Kher
Boiling Sterilizer
9/20/2011
15
Kher
Temp above 100 C Autoclave
:
Steam under pressure 15 pound per sq in 121 C x 20 min Problems : Inefficient air discharge system Load remains moist at the end
Types – Non jacketed Jacketed – takes care of both the problems
9/20/2011
16
Kher
Autoclave Drums for autoclave
9/20/2011
17
Kher
Jacketed Autoclave
9/20/2011
18
Kher
Precautions for autoclaving Do not forget to put water in the first place! Keep space for free circulation of steam Lid should be screwed air tight Keep the discharge tap open
9/20/2011
19
Kher
Allow all air to escape before applying pressure Ensure safety valve is functional & adjust to desired level Open discharge valve only after pressure has come to atmospheric level
Autoclave : Uses
9/20/2011
Articles sterilized
Articles not sterilized
Gowns, Towels, dressings, linen Glass or metal instruments Articles with glass & metal components Rubber & plastic articles Culture media, pharmaceutical products
20
Kher
Fats, oils, greases Talc & other powders Egg & serum containing media Heat labile sugars
Sterilization controls Gives you confidence! Physical Methods Continuous temp recording
Chemical Methods Autoclave tapes, spots
Biological Methods Autoclave – B. stearothermophilus
Thermocouples Browne’s tubes Hot air oven – Cl. tetani (nontoxigenic)
9/20/2011
21
Kher
Sterilizer controls Thermocouple
9/20/2011
22
Kher
indicator tape
Filtration
Basically used for heat labile liquids
Candle filters –
Unglazed ceramic e.g. Chamberland Diatomaceous earth e. g. Berkfield
Asbestos filter
Seitz filter
Sintered glass filter Membrane filters –
9/20/2011
Cellulose acetate Cellulose nitrate
23
Kher
Membrane filter
9/20/2011
24
Kher
Filter sizes
9/20/2011
25
Kher
Other Physical Methods
Radiations :
Ionizing e.g.
Non-ionizing
9/20/2011
X-rays Gamma rays Cosmic rays Infra red UV light
Ultra sonic & Sonic vibrations
26
Kher
9/20/2011
27
Kher
9/20/2011
28
Kher
Ideal Disinfectant or Antiseptic It simply doesn’t exist! Wide spectrum Effective in presence of organic material Effective at wide range of pH Speedy action Stability Compatibility with other agents
9/20/2011
29
Kher
Non-corrosive Non-irritant Non-sensitizing No interference in healing Non-toxic Safe & easy to use Cheap & easily available
Chemicals used as Disinfectants/Antiseptics
Alcohols
Formaldehyde Glutaraldhyde
Dyes
Aniline dyes
Brilliant green Malachite green Crystal violet
Kher
Iodine Chlorine & its compounds
Phenols
30
Acriflavin Proflavin Euflavin Aminacrine
Halogens
9/20/2011
Acridine dyes
Ethyl alcohol Isopropyl alcohol Methyl alcohol
Aldehydes
Carbolic acids Chlorphenols Chloroxyphenols Hexachlorphene Chlorhexidine
Chemicals used as Disinfectants/Antiseptics
Gases
Surface active agents
9/20/2011
Ethylene oxide (ETO or EO) Formaldehyde Betapropiolactone Anionic – common soaps Cationic – Cetrimide, Benzylcolium chloride Non-ionic Amphoteric
31
Kher
Metallic salts
Copper – Fungicide Silver – Crede’s prophylaxis Mercury
9/20/2011
32
Kher
ETO STERILIZER
9/20/2011
33
Kher
Efficiency of different antimicrobial chemicals
9/20/2011
34
Kher
Working concentrations of the commonly used disinfectants
Ethanol – 70%
Methylated spirit – 70%
Glutaraldehyde – 2%
Hydrogen peroxide – 3%
Savlon – 2%, 5%.
Dettol – 4%
Betadine – 2%
Ethylene oxide – 10%
Bleaching powder –
Calcium hypochlorite – 1.4% Sodium hypochlorite – 0.1 to 1%
9/20/2011
35
Kher
Methods of sterilization / Disinfection of important materials Material
Method
1
Inoculating wires & Loops
Red Heat
2
Glassware – Syringes, petridishes, test tubes, Flasks, Universal container, Oily fluids, powders
Hot air oven
3
Disposable syringes & other disposable items
Ethylene Oxide / Gamma irraditaion
4
Culture Media
Autoclaving
5
Culture Media containing serum, eggs
Inspissation (Tyndallization)
6
Toxins, sera, sugars, antibiotic solutions
Filtration
7
Milk, Milk products
Pasteurization
8
Cystoscope & Endoscopes
Glutaraldehyde
9
Operation Theatre (Fumigation)
Formaldehyde
10
Infective material like soiled dressings, beddings, animal carcasses
Incineration
11
Skin
Tincture iodine, 70% ethenol, savlon
12
Aprons, gloves, catheters, surgical instruments except sharps
Autoclaving
13
Sharp instruments
5% cresol
14
Rubber, plastic & polythene tubes
Glutaraldehyde
Testing of Disinfectants Rideal Walker test Phenol coefficient taken as 1 Comparison made of new agent with phenol Test carried out in lab conditions
9/20/2011
37
Kher
Chick Martin Test Similar to Rideal Walker test but in presence of 3% dried human faeces Indicates effectivity in field conditions
Solve this online quiz Solve
this online quiz . Ignore MCQs not related to medical microbiology.
9/20/2011
38
Kher
9/20/2011
39
Kher
9/20/2011
41
Kher
