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Sterilization: complete removal, destruction, inactivation of all forms of microbial life viruses, Fungi, bacteria, 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 Patient’s care items are divided into 3 categories: Critical items Semi-critical items Non-critical items Depending on the risk of infection due to their utilization Critical Semi critical Items enter -sterile tissues-cavitiesvascular system Items come in contact with intact mm & non intact skin e.g. needles, implants, catheters, surgical instruments e.g. endoscopes, endotracheal tube, thermometer Sterilization: EO, autoclave, plasma, sterilant High level disinfectant, glutaraldehyde, chlorine active, hydrogen peroxide Noncritical 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 microorganisms to disinfection and sterilization Resistant • • • • • • • Susceptible • • Prions Bacterial spores Mycobacteria Small non-enveloped viruses Gram-negative bacteria Fungi Large non-enveloped viruses Gram-positive bacteria Lipid enveloped viruses Decontamination Steps I. Heat 1- Moist heat or steam sterilization 2- Dry heat sterilization II. Low temperature (cold): 1. chemical a. ethylene oxide b. liquid steriliants: GLD, PAA, H2O2 2- plasma sterilizer III. Other sterilizers: 1- ionizing radiation 2- filtration 3- microwaves; in pharmaceutical industries • Heat is the most practical, efficient, and inexpensive method of sterilization and disinfection of objects that can withstand high temperatures. • There are two forms: – Moist heat is much more efficient than dry heat because: • it kills microorganisms by coagulating and denaturing their enzymes and structural proteins • it is quicker in heating up the article to be sterilized. – Dry heat is believed to kill microorganisms by causing destructive oxidation of essential cell constituents. Autoclave = saturated water steam under high pressure. heating water under controlled conditions in a closed vessel in order that boiling point of water rises above 100°C. Saturated steam carries the same temperature of boiling water. It is essential to make steam saturated and free of any residual air because air acts as an insulator, reduces temperature and hinders penetration. Sterilization temperature and exposure time : at 121°C for 20-30 minutes at double atmospheric pressure (2 bar) or at 134°C for 3-6 minutes (at 3 bar). • Steam sterilization is the most common and preferred method for sterilizing those items that can withstand high temperature and moisture, e.g. culture media, surgical instruments and dressings. Autoclave: Advantages: 1234567- Non-toxic liberation of latent heat due to condensation of steam Inexpensive Rapidly microbicidal Least affected by organic/inorganic soils Rapid cycle time Penetrates medical packing, device lumens Disadvantages: 1- Deleterious for heat labile instruments 2- Potential for burns not for powders and oils Sterilization monitored routinely by combination of mechanical, chemical, and biological parameters • Physical - cycle time, temperature, pressure • Chemical - heat or chemical sensitive inks that change color when germicidal-related parameters present • Biological - Bacillus spores that directly measure sterilization (Geobacillus stearothermophilus) Chemical Indicators