Sterilization involves the complete elimination of all forms of microbial life, including bacteria, viruses, fungi, and their resilient spores. This process is important for preventing the spread of germs and infections, particularly when instruments may come into contact with the body.
Understanding Sterilization and Disinfection
While often used interchangeably, sterilization and disinfection are distinct processes with different outcomes. Disinfection reduces the number of microorganisms on a surface, but it does not necessarily eliminate all microbial life, especially bacterial spores. Common household disinfectants, such as chemical sprays or wipes, are effective for surfaces like countertops, helping to make environments safer by targeting most viruses and fungi.
Sterilization, in contrast, eliminates virtually all microorganisms, including bacterial spores. This comprehensive removal is typically employed where complete freedom from microbes is necessary, such as medical facilities. For home use, understanding this difference helps in selecting the appropriate method based on the instrument’s intended use and the level of microbial control required.
Preparing Instruments for Sterilization
Before any sterilization, instruments must undergo thorough cleaning to remove visible debris. This initial step involves using soap and water to scrub away any organic material like blood or tissue. A brush can help reach intricate areas, ensuring all surfaces are clean.
After scrubbing, instruments should be thoroughly rinsed under running water to remove all soap residue and loosened debris. Pre-cleaning is important because organic material can shield microbes from sterilization agents, making the process ineffective. Instruments commonly found at home that might require this preparation include tweezers, nail clippers, or even gardening shears.
Practical Sterilization Methods for Home
One accessible method for sterilizing instruments at home is boiling, though it is primarily a disinfection method as it may not eliminate all bacterial spores. To disinfect by boiling, immerse clean metal instruments in a pot of water, ensuring they are fully submerged. Bring the water to a rolling boil and maintain the boil for at least 20 to 30 minutes, starting the timer once the water reaches a full boil. This method is suitable for metal tools and can also be used for some rubber or plastic equipment, though prolonged boiling can damage certain materials.
Dry heat sterilization offers another option, particularly for metal instruments that withstand high temperatures and are sensitive to moisture, using a conventional oven.
After cleaning and drying, instruments can be wrapped in four layers of clean cloth or heavy paper, or placed in a heat-safe container. Place them in a preheated oven at approximately 170°C (338°F) for one hour, or 160°C (320°F) for two hours.
Dry heat works by denaturing proteins in microorganisms, effectively destroying them. This method suits glass or metallic instruments but not rubber or plastic items, as they will melt.
Household bleach solutions can be used for disinfection and, with higher concentrations or longer contact, for sterilization of certain items. A common disinfection dilution is 1:10 (one part bleach to ten parts water), or about 1½ cups per gallon, or 4 teaspoons per quart. Instruments should be cleaned and dried before immersion, ensuring all surfaces are covered. A contact time of at least 10 minutes is recommended for effective disinfection.
Bleach is corrosive to metals, so instruments should be rinsed thoroughly with water after treatment to remove residues and prevent damage. Bleach solutions should be prepared fresh daily as effectiveness degrades over time.
Safe Handling and Storage Post-Sterilization
After sterilization, maintaining instrument sterility is important to prevent recontamination. Instruments should cool and dry completely before handling, as moisture can compromise sterility. Once dry, handle instruments with clean hands or gloves to avoid introducing microorganisms.
To preserve sterility, store instruments in clean, dry, sealed containers or sterile pouches. These protect instruments from environmental contaminants like dust and airborne bacteria. Store them in a clean, dust-free environment, preferably in closed cabinets, to maintain their sterile state until next use. Once exposed to air or touched by unsterile hands, a sterilized instrument is no longer sterile and should be reprocessed if sterility is required.