definition sterilization: the freeing of an article from all living organisms including bacteria and...

DefinitionDefinition

Sterilization: The freeing of an article from all living organisms including bacteria and their spores.

Disinfection: Removal of some types of pathogenic organisms usually not including spores.

Heatdry & moist

Sterilization by heatSterilization by heatA. Dry heatA. Dry heat

Hot air oven:◦Electrically heated◦Thermostat◦Fan

Holding time:◦160° C 2hs◦180° C 1h

Used for:◦Glass◦Metals◦Dry material in sealed

container: oil, powder

PrecautionsGlass: good quality, dryObject put while oven is

coldHolding time:

calculated?Oven left to cool

Sterilization by heatSterilization by heatA. Dry heatA. Dry heat

Sterilization by heatSterilization by heatB. Moist heatB. Moist heat

1. Below 1001. Below 100°C°C

Sterilization by heatSterilization by heatB. Moist heatB. Moist heat2. At 1002. At 100°C°C

Sterilization by heatSterilization by heatB. Moist heatB. Moist heat2. At 1002. At 100°C°C

Sterilization by heatSterilization by heat B. Moist heat B. Moist heat

2. At 1002. At 100°C°C

Double walled metal cylinder

Lid: tightly fitted with clamps

Manometer: measure pr.Safety valve: exit of

excess heat when pr. Exceeds the required

Sterilization by heatSterilization by heat B. Moist heat B. Moist heat

3. Above 1003. Above 100°C°C (Autoclave) (Autoclave)

Principle (Heating under pressure)

Water is boiling at normal atmospheric pr. At 100°C

When pr to 2 atmospheric pr. temp. of water boiling (steam pr.) is 121°C

Temp.: 121°C at 2 atmospheric pr. for 20 min

Sterilization by heatSterilization by heat B. Moist heat B. Moist heat

3. Above 1003. Above 100°C°C (Autoclave) (Autoclave)

UsesSterilization of most

culture mediaSergical objects as:

dressings, towels, surgical instruments (scissors, clamps, arteries, retractors,…….)

Sterilization by heatSterilization by heat B. Moist heat B. Moist heat

3. Above 1003. Above 100°C°C (Autoclave) (Autoclave)

Hospital autoclavesHospital autoclaves

Wrapping of itemsWrapping of items

Tap with chemical indicator used Tap with chemical indicator used to verify sterilization processto verify sterilization process

Filtration

Principle◦Removal of bacteria from fluids

by passing them through filters with pores so small that bacteria are arrested.

Sterilization by Sterilization by filtrationfiltration

Sterilization by Sterilization by filtrationfiltrationUses

◦Preparation of soluble bacterial products as toxinstoxins.

◦Sterilization of liquids that would be damaged by heat as sera, antibiotics & vaccines.

Efficiency of the filtration:

retain Serratia marcescens average pore diameter 0.75 µm or less.

Seitz filters ◦Formed of asbestos with pore size 0.5-0.75µm.

◦Used for removing bacteria from serum and fluid culture media.

Sterilization by Sterilization by filtrationfiltrationTypesTypes

Membrane filters◦e.g. cellulose acetate-Millipore filter.

Disposable membrane filters Disposable membrane filters Left: a filter system designed for small volumes. Left: a filter system designed for small volumes. Right: a filter system designed for larger volumesRight: a filter system designed for larger volumes

Earthenware candlesEarthenware candles

Sintered filtersSintered filtersGlass filter

HEPA filter (High-efficient-particle-Arresters) Air sterilization ◦ICUs ◦OR◦isolation rooms. ◦safety cabinet in

microbiology labs

Irradiation

a)-Ultraviolet radiation: ◦Mercury lamp.Mercury lamp.

Uses: ◦Operating theatre. ◦Inoculation chamber

for viruses. ◦Water. ◦Killing of vaccines.

Sterilization by Sterilization by IrradiationIrradiationTypesTypes

Irradiation

b)- Ionizing irradiation (gamma rays) : ◦ Cobalt 60Cobalt 60.

Uses:

◦ Sterilization of an article an article not stand the heat not stand the heat as rubber catheters, cat gut or plastic syringes.

Low temperature sterilizationLow temperature sterilization