STERILISATION AND DISINFECTION
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Transcript of STERILISATION AND DISINFECTION
By T.Divya R.Manjeera Bharat Kishore.
STERILISATION AND
DISINFECTION
LABORATORY SAFETY Wear gloves Wash hands after working with
infectious materials Disinfect all instruments after use Use water to moisten specimen labels Disinfect all contaminated waste
before discarding Report to appropriate personnel all
accidents or exposures to infectious agents
STERILISATIONThe process by which an article ,surface or
medium is freed of all living microorganisms either in the vegetative or spore state.
Object of Sterilisation :Uses:- .to prevent contamination by
organisms in surgery to maintain asepsis .in food manufacture .in drug manufacture Methods :depend on purpose,material
and nature of microorganisms to be removed or destroyed
DISINFECTION :- destruction or removal of all pathogenic organisms or organisms capable of giving rise to infection.
ANTISEPSIS :- prevention of infection usually by inhibiting the growth of bacteria in wounds or tissues.
ANTISEPTICS :-chemical disinfectants which can be safely applied on skin and mucous membrane
BACTERICIDAL AGENTS or GERMICIDES :-those which are able to kill bacteria
BACTERIOSTATIC AGENTS :-prevent multiplication of bacteria which may however remain alive
CLEANING :-an important preparatory role before sterilisation by removing soil and other dust , reducing microbial burden making sterilisation more effective.
DECONTAMINATION :-process of rendering an article or area free of danger from contaminants.
A. PHYSICAL AGENTS Sunlight Drying Dry heat:flaming,incineration,hot air Moist heat :pasteurisation,boiling,steam
under pressure Filtration Radiation Ultrasonic and sonic vibrations
B. CHEMICAL AGENTS Alcohols :ethyl,isopropyl,trichlorobutan
ol Aldehydes :formaldehyde,glutaraldehyd
e Dyes Halogens Phenols Surface active agents Metallic salts Gases:ethylene
oxide,formaldehyde,betapropiolactone
1.SUNLIGHT bactericidal activity spontaneous sterilisation under
natural conditions action is due to uv rays Germicidal effect due to uv and heat
rays
2.DRYING unreliable spores are unaffected
3 .HEAT reliable Factors influencing nature of heat temperature and time no.of microorganisms present characteristics of organisms type of material from which the
organisms have to be eradicated
THERMAL DEATH TIME :-minimum time required to kill a suspension of organisms at a predetermined temperature in a specified environment.
STERILISATION TIME depends on no. of organisms in suspension spores characteristics of organisms
DRY HEAT FLAMING : bunsen flame
INCINERATION :an excellent method for safely destroying hospital wastes
INCINERATOR
HOT AIR OVEN widely used temperature 160 C time 1 hour sterilises
glassware,foreceps,scissors,scalpels,syringes,swabs
Oven is heated by electricity It is fitted with a fan for even distribution
of air Should not be overloaded Glassware should be perfectly dry before
being placed in the oven 180 C –cotton plugs get charred 150 C , 2hrs –instruments used in
ophthalmic surgery 150 C , 1hr –oils, glycerol and dusting
powder Oven is allowed to cool slowly for 2 hrs.
Sterilisation control :Spores of non toxigenic strain of
Clostridium tetani are usedPaper strips impregnated with 106
spores placed in envelopes inserted into suitable packs
sterilisation
Strips removed and inoculated into
thioglycollate or cooked meat media
Incubated for sterility test under strict anaerobic conditions for 5 days at 37 C
Brownes tube
MOIST HEAT 1. Temp. below 100 C Pasteurisation of milk : Holder method :63 C , 30
min. Flash process :72 C , 15-20
sec. Cooled quickly to 13 C
Non sporing pathogens destroyed Coxiella burnetti survives holder
method Inspissator 80 C , 5 -10 min.-
bacteria ,yeasts moulds 60 C , viruses
2. Temp. at 100 Ca) Boiling : vegetative
bacteria killed spores not killedb) Steam at atmospheric
pressure 100 C Koch or Arnold steamer
STEAMER
TYNDALLISATION or INTERMITTENT STERILISATION
100 C ,20 min , 3 successive days
C) Steam under pressure : Temp. 108 C -147 C :
dressings,instruments,laboratory ware,media,pharmaceutical products sterilised
For aqueous solutions 108 C -126 C Steam sterilisers laboratory autoclaves hospital dressing sterilisers bowl and instrument sterilisers rapid cooling sterilisers
HOSPITAL DRESSING STERILISER
INSTRUMENT STERILISER
RAPID COOLING STERILISER
PRESSURE COOKER
LABORATORY AUTOCLAVE
PRINCIPLE –Water boils when its vapour pressure equals that of the surrounding atmosphere.
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LABORATORY AUTOCLAVE
DEFECTS The method of air discharge is inefficient if air is not completely removed , the desired temperature is not attained There is no facility for drying the load after sterilisation and before taking it out. STERILISATION CONTROL :spores of Bacillus stearothermophilus are used
as the test organism.Spores require 121 C , 12 min. to get killed