Sterilization: complete removal, destruction, inactivation of all forms of microbial life

viruses, viruses, Fungi,Fungi,bacteria, bacteria, Spores. Spores.

• Disinfection: elimination of most pathogenic organisms excluding sporicidal activity. There are 3 levels;

•HLD, all vegetating bacteria, MTB, fungi, all viruses

•ILD, all vegetating bacteria, MTB, majority of fungi, majority of viruses

•LLD, vegetating bacteria except MTB, some fungi, some viruses

•Antiseptics: chemical disinfectants applied to skin, mm but not systemic

•Cleaning: removal of dust, dirt, organics, FM.

•Decontamination: general term applied to any procedure by which microorganisms are reduced to a level where items are safe to handle

•Antiseptics: chemical disinfectants applied to skin, mm but not systemic

•Cleaning: removal of dust, dirt, organics, FM.

•Decontamination: general term applied to any procedure by which microorganisms are reduced to a level where items are safe to handle

Patient’s care items are divided into 3 Patient’s care items are divided into 3 categories:categories:

Critical itemsCritical items

Semi-critical itemsSemi-critical items

Non-critical itemsNon-critical items

Depending on the risk of infection due to their utilizationDepending on the risk of infection due to their utilization

Critical Semi critical NoncriticalCritical Semi critical Noncritical

Items enter -sterile tissues-cavities-vascular system

e.g. needles, implants, catheters, surgical instruments

Sterilization: EO, autoclave, plasma, sterilant

Items come in contact with intact mm & non intact skin

e.g. endoscopes, endotracheal tube, thermometer

High level disinfectant, glutaraldehyde, chlorine active, hydrogen peroxide

Items come in contact with intact skin

e.g. sphygmomanometers, bed linens, floors

Intermediate and low level disinfectants, alcohols, phenols

Decreasing order of resistance of Decreasing order of resistance of microorganisms to disinfection and microorganisms to disinfection and

sterilizationsterilization ResistantResistant

SusceptibleSusceptible

• Prions Prions

• Bacterial spores Bacterial spores

• MycobacteriaMycobacteria

• Small non-enveloped Small non-enveloped virusesviruses

• Gram-negative Gram-negative bacteria bacteria

• Fungi Fungi

• Large non-enveloped Large non-enveloped virusesviruses

• Gram-positive bacteria Gram-positive bacteria

• Lipid enveloped Lipid enveloped virusesviruses

Decontamination StepsDecontamination Steps

I. HeatI. Heat

1- Moist heat or steam sterilization1- Moist heat or steam sterilization

2- Dry heat sterilization2- Dry heat sterilization

II. Low temperature (cold):II. Low temperature (cold):

1. chemical1. chemical

a. ethylene oxidea. ethylene oxide

b. liquid steriliants: GLD, PAA, H2O2b. liquid steriliants: GLD, PAA, H2O2

2- plasma sterilizer2- plasma sterilizer

III. Other sterilizers:III. Other sterilizers:

1- ionizing radiation1- ionizing radiation

2- filtration2- filtration

3- microwaves; in pharmaceutical 3- microwaves; in pharmaceutical industriesindustries

• Heat is the Heat is the most practical, efficient, and most practical, efficient, and inexpensiveinexpensive method of sterilization and method of sterilization and disinfection of objects that can withstand high disinfection of objects that can withstand high temperaturestemperatures. .

• There are two forms:There are two forms: – Moist heatMoist heat is much is much more efficientmore efficient than dry heat than dry heat

because: because: • it kills microorganisms it kills microorganisms by coagulating and by coagulating and

denaturing their enzymes and structural proteinsdenaturing their enzymes and structural proteins • it is quicker in heating up the article to be sterilized.it is quicker in heating up the article to be sterilized.

– Dry heatDry heat is believed to kill microorganisms by causing is believed to kill microorganisms by causing destructive oxidation of essential cell constituentsdestructive oxidation of essential cell constituents..

Autoclave = Autoclave = saturated water steam under high pressure. saturated water steam under high pressure. heating water under controlled conditions in a closed vessel in heating water under controlled conditions in a closed vessel in order that boiling point of water rises above 100°C. order that boiling point of water rises above 100°C.

Saturated steam carries the same temperature of boiling Saturated steam carries the same temperature of boiling water. water.

It is essential to make steam saturated and free of any It is essential to make steam saturated and free of any residual residual air because air acts as an insulator, reduces temperature and air because air acts as an insulator, reduces temperature and hinders penetration. hinders penetration.

Sterilization temperature and exposure time : Sterilization temperature and exposure time : at 121°C for 20-30 minutes at double atmospheric pressure (2 at 121°C for 20-30 minutes at double atmospheric pressure (2 bar)bar)or at 134°C for 3-6 minutes (at 3 bar). or at 134°C for 3-6 minutes (at 3 bar).

Autoclave = Autoclave = saturated water steam under high pressure. saturated water steam under high pressure. heating water under controlled conditions in a closed vessel in heating water under controlled conditions in a closed vessel in order that boiling point of water rises above 100°C. order that boiling point of water rises above 100°C.

Saturated steam carries the same temperature of boiling Saturated steam carries the same temperature of boiling water. water.

It is essential to make steam saturated and free of any It is essential to make steam saturated and free of any residual residual air because air acts as an insulator, reduces temperature and air because air acts as an insulator, reduces temperature and hinders penetration. hinders penetration.

Sterilization temperature and exposure time : Sterilization temperature and exposure time : at 121°C for 20-30 minutes at double atmospheric pressure (2 at 121°C for 20-30 minutes at double atmospheric pressure (2 bar)bar)or at 134°C for 3-6 minutes (at 3 bar). or at 134°C for 3-6 minutes (at 3 bar).

• Steam sterilization is Steam sterilization is the most common the most common and preferred and preferred method for method for sterilizing those sterilizing those items that can items that can withstand high withstand high temperature and temperature and moisture, e.g. moisture, e.g. culture media, culture media, surgical instruments surgical instruments and dressings.and dressings.

Autoclave:Advantages:

1- Non-toxic2- liberation of latent heat due to condensation of steam3- Inexpensive4- Rapidly microbicidal5- Least affected by organic/inorganic soils6- Rapid cycle time7- Penetrates medical packing, device lumens

Disadvantages:

1- Deleterious for heat labile instruments2- Potential for burns not for powders and oils

Sterilization monitored routinely Sterilization monitored routinely by combination of mechanical, by combination of mechanical, chemical, and biological chemical, and biological parametersparameters

• Physical - cycle time, Physical - cycle time, temperature, pressuretemperature, pressure

• Chemical - heat or chemical Chemical - heat or chemical sensitive inks that change color sensitive inks that change color when germicidal-related when germicidal-related parameters presentparameters present

• Biological - Biological - Bacillus Bacillus spores that spores that directly measure sterilization directly measure sterilization ((Geobacillus stearothermophilus)Geobacillus stearothermophilus)

Chemical IndicatorsChemical Indicators