1- Low temperature steam: dry steam at 73C° for 20 minutes at sub atmospheric pressure. 2- Boiling water exposure to 100C° for 5 minutes at normal pressure. 3-Formaldehyde gas exposure in specialized cabinet at 50C°. 4-Glutaraldehyde 2% effective for heat sensitive material like flexible endoscopes, but its toxic and cause allergic reaction.

Methods of Sterilization 1- Autoclave: specialized container supply moist steam under pressure with high temperature. Used for metal ware, glassware, rubber and dry goods. The temp and time needed are: 3 minutes at (132°C), 8 minutes at (125°C), 15 minutes at (118°C). 2-Ethylene oxide: A penetrative non corrosive gas used to sterilizes heat and moist sensitive substance. 3-Irradiation:Using gamma ray to sterilize syringes, catheters, cannulas and other plastic tubes and heat sensitive objects. 4- Peracitec acid: chemical agent cause protein denaturation suitable for endoscopes.

1- Povidone iodine: Can be used to disinfect skin before operation and to clean infected wounds and ulcers. Side effects: allergy, metabolic acidosis, interfere with thyroid function test, not recommended in pregnancy, not used inside abdominal cavities. 2- Chlorhixidine: Effective against gram positive MO. Can be used to disinfect skin before operation and to clean infected wounds und ulcers. 3- Alcohol: 70% used as disinfectant to prepare skin for operation, not used for wound or ulcer. 4- Hydrogen peroxide: Week disinfectant help to flush out depress from cavities by mechanical action.

1) At patient level 1- Avoid prolonged preoperative hospital stay. 2- Control any source of infection if possible. 3- Control DM, uremia, anemia, malnutrition, electrolyte disturbance. 4-Preoperative bathing. 5-Stop smoking. 5- Avoid shaving the area of operation, if this is mandatory it should be on the table. 6- Prophylactic antibiotic. 7-Early post operative mobilization and exercise.

2) At staff level 1-Staff with focus of infection should not deal with patients. 2-Decrease number of staff in the operative theatre with less movement as possible. 3-Warring of special clothes and gowns. 4- Using the head caps, face mask and boots. 5- Hand washing. 6- Warring sterile gloves during surgical procedure and usual gloves when dealing with infective focus.

3) At operative theatre level 1- The operative theatre design and building. 2- The ventilation system. 3- The table and light source. 4-Anesthetic machines and equipments. 5-Suckers and electro- cauterization devices. 6- Surgical instruments.

4) At surgical word and medical devices level 1- Surgical word devices including: beds, mattresses, pillows, urinals and surgical truly. 2-Reception and examination rooms. 3- Canula, IV set line, drains, tubes and blood transfusion sets. 4- The visitors.

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