Sterilization and Disinfection Methods

Study Notes

Sterilization eliminates ALL microorganisms, including highly resistant bacterial spores. It's used for sterilizing medical equipment.
Disinfection kills or inhibits many, but not all, microorganisms. Some organisms and spores may survive. Example: Disinfection of the skin before blood collection using 70% ethanol.
Disinfectants are antimicrobial agents applied to non-living objects to destroy microorganisms.
Antiseptics are antimicrobial substances applied to living tissue/skin to reduce infection and sepsis.

Chemical agents disrupt cell membranes, modify proteins, or act as oxidizing agents.
- Alcohols (ethanol/isopropyl alcohol): Maximal activity at 70%. Kills bacteria and fungi, but not spores. Used in hand sanitizers and antiseptic swabs.
- Phenols are powerful disinfectants, effective against a wide range of microorganisms.
- Chlorine kills bacteria, viruses, and fungi but not spores. Used for disinfecting surfaces.
- Iodine is a potent antiseptic, effective against a wide range of microorganisms.
- Heavy metals have antimicrobial properties but are often toxic.
- Hydrogen peroxide is an oxidizing agent used as a disinfectant and antiseptic.
- Formaldehyde & Glutaraldehyde are strong disinfectants used for sterilizing medical instruments.
Physical agents target microorganisms through heat, radiation, or filtration.
- Heat is a common method for sterilization.
  - Moist heat (autoclave) uses high pressure steam to sterilize materials like surgical instruments, culture media, linen, plastic ware, and solutions.
- Radiation uses UV light, X-rays, or gamma rays to sterilize medical supplies and food products.
- Filtration is used to remove bacteria and other microorganisms from liquids or gases.

Chlorine tablets are used to disinfect surfaces. They kill bacteria, viruses, and fungi but not spores.

Virkon is a powerful disinfectant effective against viruses, bacteria, and fungi but less effective against spores.

Alcohol-based hand sanitizer is an antiseptic commonly used for hand hygiene.

Chlorhexidine Gluconate is a chlorinated phenol used as a hand scrub before surgery and for wound cleansing.

Heat is effective for sterilization.
Radiation uses ultraviolet (UV) light, X-rays, or gamma rays to sterilize materials.
Filtration separates microorganisms from liquids or gases.

Autoclaves use moist heat (high-pressure steam) to sterilize materials.
Applications include surgical instruments, culture media, linen, plastic ware, solutions, and water.