By  T.Divya  R.Manjeera  Bharat Kishore.

 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

The 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,trichlorobutanol  Aldehydes :formaldehyde,glutaraldehyde  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,syring es,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 used Paper 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, sec.  Cooled quickly to 13 C

Non sporing pathogens destroyed  Coxiella burnetti survives holder method  Inspissator  80 C, min.-bacteria,yeasts moulds  60 C, viruses

2. Temp. at 100 C a) Boiling : vegetative bacteria killed spores not killed b) Steam at atmospheric pressure 100 C  Koch or Arnold 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

 LABORATORY AUTOCLAVE  PRINCIPLE –Water boils when its vapour pressure equals that of the surrounding atmosphere.

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