Sterilization And Disinfection Flashcards
Sterilization definition
Removal of pathogens including spores
Disinfection definiton
Removal of Pathogens but not spores
Asepsis definition
To make body surface/skin/wound free of mirco-organisms
Sterilization methods are divided into
Physical
Chemical
Physical Sterilization methods includes
Heat
Filtration
Radiation
Chemical sterilization methods includes
Alcohol
Aldehydes
Phenols
Halogens
Oxidizing agents
Plasma sterilization
Gas sterilization
Heavy metal salts
Surface acting agents
Dyes
Heat method of Sterilization is divided into
Dry heat
Moist heat
Examples of Dry heat methods
Candle
Flame burners
Sunlight
Hot air oven
Incinerator
Mechanism of Dry heat Sterilization methods
CODE
Charring
Oxidative damage
Denaturation of proteins
Elevation of electrolytes
Hot air oven temperature and duration
160°C for 2 hr
For every 10° increase in temperature - time should be decreased by half
For Ex. 170°C × 1hr, 180°C x 30 min
Hot air oven is used to sterilize
Glasswares
Cotton swabs
Wax, oils, powder gels
Dusting powder
Greasy paraffin wax
Metallic (sharp and non sharps)
Physical control of Hot air oven
Temperature monitoring by thermocouples
Chemical control of Hot air oven
Brownies tube (green spot)
Biological control of Hot air oven is done by
C. Tetani or Bacillis subtilis/atropheus
Incinerator is used for sterilization of
Hospital waste
Human anatomical waste
Animal carcasses
Expired Cytotoxic drugs
Temperature maintained in Incinerator
2 chambers - 700-800°C and 1000-1100°C
Mechanism of Moist heat Sterilization
Coagulation and denaturation ot proteins
Which Heating sterilization method is considered better - Dry or Moist heat
Moist heat
Moist heat Sterilization methods classification on basis of temperature
1) Below 100°C - IPL100 - Inspissation, Pasteurisation, Vaccine water bath
2) At 100°C - BAT - Boiling and Tyndalisation
3) Above 100°C - Autoclave
Methods or Milk Pasteurisation
Holder method
Flash method
Ultra high temperature method
Holder method of milk Pasteurisation temperature and duration
63°C for 30 minutes
Temperature and duration of Flash method of Milk Pasteurisation
72°C for 20 seconds - Rapidly cool it to <13°C
Ultra high temperature method of Milk Pasteurisation
149°C for 1-2 sec
Which method of Milk Pasteurisation is better
Flash method as it kills Coxiella brunetti
Tests for efficacy of Pasteurisation
1) Phosphatase test - On adding substrate - no color change (enzymes denatured)
2) Coliform test - No growth on MacConkey agar
Temperature and duration for Inspissation method
80°C for 20-30 min for 3 consecutive days
80-80-80
Inspissation method is used for sterilization of
Lowenstein Jensen media
Loeffler’s serum slope
Temperature and duration of Vaccine water bath method and uses
60°C for 1 hour
Bacterial vaccines are heat inactivated
Temperature and duration for Boiling method
At 100°C for 15 min
Doesn’t kill spores
Temperature and duration for Tyndalisation method of Sterilization
At 100°C for 20 min for 3 consecutive days
Kill spores
Tyndalisation Method is used for sterilization of
Used for media with gelatin/sugar
TCBS
XLD
DCA
Selenite F broth
Temperature and duration of Autoclave method
121°C for 15 min for 15psi
To kill Prions - 134°C × 1.5 hrs
Control used for Autoclave
Bacillus Stearothermophilus
Uses of Autoclave method
Instruments (non sharps)
Aprons
Sutures except catgut sutures
Media except LJ and LSS
Sputum (prior to descending)
Average Pore size in Filtration method
0.22 micron
Types of Filtration methods
Depth filters
Membrane filters
Depth filters include
Candle filters
Seitz filters - not used
Glass filters
Membrane filters includes
Cellulose acetate
Cellulose nitrate
Uses of Filtration method of Sterilization
For heat sensitive substances
Vaccine
Antibiotics
Serum
Toxins
Sugar solutions
Control of Filtration method is done by
Brevendimonas diminuta (chota chota)
Serratia
HEPA full form and its efficacy
High efficacy particulate air filter
99.97% efficacy
ULPA full form and it’s efficacy
Ultra low particulate air filter
99.999% efficacy