Sterilization and Disinfection Quiz

Sterilization, Disinfectants, and Antiseptics

• Sterilization: Killing all forms of microbes, including spores
• Disinfectants: Antimicrobial agents applied to non-living objects to reduce pathogenic microorganisms
• Antiseptics: Antimicrobial substances applied to living tissue/skin to reduce infection risk. Not all disinfectants are antiseptics; antiseptics must not harm living tissue.

Sterilization Methods

• Divided into chemical and physical methods
  • Chemical Sterilization: Typically used for heat-sensitive devices or materials susceptible to damage from irradiation (e.g., rubber, plastics).
    • Subdivided into chemical liquid and chemical vapor sterilization methods

Chemical Liquid Sterilization

• Classifications of disinfectants: high-level, intermediate-level, and low-level, based on their efficacy against different types of microbes (e.g., vegetative bacteria, spores).

• High-level disinfectants: Effective against a large number of microbes including spores following prolonged exposure (e.g., Hydrogen peroxide (3-6%))

• Intermediate-level disinfectants: Effective against few numbers of spores and microbes (e.g., 70% ethyl alcohol and isopropyl alcohol)

• Low-level disinfectants: Primarily effective against vegetative bacteria and some fungi (e.g., Providone-iodine 5% and 10%)

Chemical Vapor Sterilization

• Chemical Vapor Under Pressure (Chemiclave): Sterilization process using a mixture of chemicals (e.g., alcohol, formaldehyde, ketone) heated under pressure to form a sterilizing gas. Requires specific time and temperature (e.g., 20 minutes at 131°C and 20 lbs pressure).
• Fumigation: Sterilizing using potassium permanganate mixed with formalin in a specific ratio (w/v 2:3) to produce a fumigant.

Physical Sterilization Methods

• Utilizes physical agents or processes to eliminate or inactivate microorganisms (e.g., bacteria, viruses, spores).
• Includes autoclaving, dry heat sterilization, filtration, radiation, and ultraviolet (UV) radiation.

Autoclaving

• Uses pressurized steam at high temperatures (e.g., 121°C or 250°F) for a defined period (e.g., 15-20 minutes) to sterilize media, instruments, surgical tools, and biohazardous waste. Effective due to combined heat and moisture effects.

Dry Heat Sterilization

• Involves heating materials to high temperatures (160-180°C or 320-356°F) for a period (e.g., 1-2 hours) in a dry oven. Suitable for sterilizing metal instruments, glassware, and powders. Works by oxidizing microbial cells.

Filtration

• Removes microorganisms from liquids or air using filters with small pores. Useful for heat-sensitive liquids (e.g., vaccines, enzyme solutions).

Radiation

• Uses gamma rays or electron beams to break down DNA of microorganisms, sterilizing materials. Effective even for heat-sensitive materials.

UV Radiation

• Uses UV-C light (at specific wavelength) to damage the DNA of microorganisms, preventing replication. Commonly utilized for surface sterilization.

Boiling

• Boiling water (100°C or 212°F) for a period (10-15 minutes) can kill many bacteria and viruses but may not be effective against all spores. Useful for certain household items and in emergencies.

Incineration

• Destroys contaminated materials through high-temperature burning. Suitable for disposable medical waste like contaminated dressings or sharps.

Laboratory Safety and Accident Prevention

• Includes general safety precautions, first aid measures, handling of chemical and biological hazards, and proper use of personal protective equipment (PPE).