Concept & Need to Sterilize instruments
• Pakistan carries one of the world's highest burdens of chronic hepatitis and mortality due to liver failure and hepatocellular carcinomas.
• Contaminated needle use in medical care ,drug abuse, unsafe blood and blood product transfusion .
• 19 million, of Pakistan’s population of 160 million are suffering from hepatitis.
• One out of every 10 Pakistanis suffers from either Hepatitis B or C.
• 40,000 - 45,000 cases of H.I.V./ A.I.D.S. since 1986.
Terms & Definition• Sepsis: Breakdown of living tissue by
action of microorganisms and is usually accompanied by inflammation.
• Asepsis: Avoidance of sepsis.• Antiseptic and disinfectants:
Substances that can prevent the multiplication of organisms capable of causing infection.
• Sterility: Freedom from viable forms of microorganisms.
Universal Precautions
• “All patients and blood contaminated body fluids are treated as infectious”.
• What body fluids can be highly infectious? Semen, vaginal secretions, synovial fluid, cerebrospinal fluid, pleural fluid, peritoneal fluid, pericardial fluid, amniotic fluid.
How to follow Universal precautions?
• Recognition of potential hazards (body fluids)
• Personal protective equipment (P.P.E.): Use of barriers e.g. gloves, lab coat, masks, eye shield, facemask etc.
• Knowledge and application of techniques that reduce the exposure e.g. hand washing, disposal of contaminated needles, disposal of body fluids.
Sterilization & Types• Sterilization is defined as the process that
destroys all forms of microbial life including bacteria, fungi, viruses as well as bacterial spores.
• Types of sterilization
Physical Chemical
(Dry heat, moist heat, autoclave, (Ethylene Oxide radiation) Aldehydes,Ozone)
Physical Methods of Sterilization
• Heat: Protein denaturation, coagulation, oxidative damage to cells.
• Moist heat superior to dry heat; quick and lower temperature.
• Steam pressure sterilization (Autoclaving): Utilizes steam under increased pressure. Uses 121 0 C at 15 Ibs Pressure for 15 minutes or 134 0 C at 30 Ibs pressure for 4 minutes.
• Irradiation: Gamma rays or accelerated electrons used.
Chemical Methods• Ethylene Oxide: Rapidly destroys spores.• Highly flammable, hence mixed with CO2 or
Nitrogen to make it safer.• Gas concentration: 200 -800 mg/l,
Temperature: 30-60 0 C, Humidity: 45-85%, Time: 3 hours.
• Aldehydes (Formaldehyde, Gluteraldehyde & Phthalaldehyde) : Formaldehyde slower action, 2% Gluteraldehyde requires 3 hours immersion, 0.55% solution Phthalaldehyde better and quicker action than Gluteraldehyde and effective against Gluteraldehyde resistant spores.
Technique Advantages Disadvantages Comments
Autoclave Rapid, effective for dental instruments, surgical packs & towels packs.
Items sensitive to heat e.g. carbon steel instruments, carbide and diamond burs corrode.
121 0 C 15 Ibs 15 mins134 0 C, 30 Ibs 4 mins
Dry heat Items sensitive to heat e.g. carbon steel instruments, carbide and diamond burs can be sterilized.
Rubber, plastic instruments cannot be sterilized.Maximum sterilization failures.
160 0 C 60 minutes, 170 0 C 40 minutes, 180 0 C 20 minutes.Don’t open until temperature falls below 60 0 C
Ethylene Oxide Heat & moisture sensitive articles, electrical equipment.
Toxic, flammable, carcinogenic.
Gas:200 -800 mg/l, Temperature: 30-60 0 C, Humidity: 45-85%, Time: 3 hours.
Irradiation Syringes, gloves, plastic dishes, glassware, antibiotics
Poor penetrative power and costly.
Sterilizing dose: 25 K Gy in few seconds.
Aldehydes. Heat sensitive instruments.
Irritant, carcionogenic, inactivated by proteins.
Variable time :10 mins to 3 hours.
Sterilization Check
• Sterilization bags and tapes change color upon exposure to heat and sterilization chemicals.
• If used alone, reliability is questionable.
• Commercially available bacterial spores.
• Bacillus strarothermophilus; evaluation of heat sterilization.
Other Measures
• Do not store gloves in sunlight to prevent oxidation; store in tightly closed plastic bags.
• Remove watches, jewelry, rings before treatment.
• Wash hands when changing gloves.• Chlorhexidine hand cleaners preferred.• Head rest, light handle, tray table can be
covered with disposable cover/sheets.• If several patients waiting, treat the non-
infectious patients first.