Microbiology ||Sterilization and Disinfection in Nursing Practice || For Nursing Students ||

 

Sterilization and Disinfection in Nursing Practice


1. Principles of Sterilization and Disinfection

Sterilization and disinfection are critical to infection prevention in healthcare settings. Their principles ensure the elimination or reduction of harmful microorganisms to maintain a sterile environment.

Principles of Sterilization

  1. Complete Elimination: Sterilization destroys all forms of microbial life, including spores.
  2. Selection of Method: Choose the method based on the material (e.g., heat-resistant, moisture-sensitive).
  3. Effectiveness: Factors like temperature, pressure, duration, and chemical concentration must be optimized. 

Principles of Disinfection

  1. Reduction of Pathogens: Disinfection reduces microorganisms to levels that are not harmful.
  2. Contact Time: The effectiveness of disinfectants depends on adequate exposure time.
  3. Surface Compatibility: Use agents compatible with surfaces and instruments.
  4. Target Specificity: Disinfectants should target specific pathogens present in the area.

2. Methods of Sterilization

Definition of Sterilization

Sterilization is a process that destroys all forms of microbial life, including bacteria, viruses, fungi, and spores, using physical, chemical, or biological methods.

Physical Methods

  1. Heat Sterilization:

    • Moist Heat (Autoclaving): Steam at 121°C–134°C under pressure for 15–30 minutes. Used for surgical instruments, dressings, and lab equipment.
    • Dry Heat: Hot air ovens at 160°C–180°C for 1–2 hours. Used for glassware and oils.
    • Boiling: Limited use for basic decontamination at 100°C for 30 minutes.

  2. Radiation:

    • Ultraviolet (UV): Used for surface sterilization in operating rooms.
    • Gamma Radiation: For single-use medical devices and packaged items.

  3. Filtration:

Chemical Methods

  1. Ethylene Oxide (EtO) Gas: Used for heat-sensitive items like endoscopes and catheters.
  2. Plasma Sterilization: Uses hydrogen peroxide vapor for quick sterilization of delicate instruments.
  3. Chemical Sterilants: Glutaraldehyde and peracetic acid are used for sterilizing surgical instruments.

Biological Methods

  1. Biological Indicators: Test sterilization effectiveness using spores of Geobacillus stearothermophilus or Bacillus atrophaeus.
  2. Enzymatic Decontamination: Utilized for cleaning instruments with protein-based contaminants.

3. Types of Disinfectants and Their Uses

High-Level Disinfectants

  1. Glutaraldehyde (2%): Used for endoscopes and heat-sensitive instruments.

    • Concentration: Soak for 20–30 minutes.
    • Caution: Can irritate skin and respiratory tract.

  2. Hydrogen Peroxide (6–30%): Disinfects surfaces and instruments.

    • Concentration: Applied for 10–30 minutes.
    • Caution: Corrosive at higher concentrations.

Intermediate-Level Disinfectants

  1. Alcohol (70% Ethanol or Isopropyl): Used for skin antisepsis and surface disinfection.

    • Concentration: Applied as a spray or wipe.
    • Caution: Highly flammable, evaporates quickly.

  2. Chlorine Compounds (Sodium Hypochlorite 0.5–1%): Used for spills and environmental cleaning.

    • Concentration: 0.5% for general cleaning; 1% for high-risk areas.
    • Caution: Corrosive to metals.

Low-Level Disinfectants

  1. Phenolics (0.4–5%): Used for non-critical items like furniture.
    • Caution: Harmful to skin and mucous membranes.
  2. Quaternary Ammonium Compounds (QACs): For floors and walls.
    • Caution: Limited activity against some pathogens like spores.

4. Infection Control Practices in Healthcare Settings

Universal Protocols for Infection Control 

  1. Hand Hygiene:

    • Wash hands with soap and water for 20 seconds or use alcohol-based hand rub.

  2. Use of Personal Protective Equipment (PPE):

    • Wear gloves, masks, gowns, and eye protection as required.

  3. Safe Injection Practices:

    • Use sterile needles and syringes. Dispose of sharps in designated containers.

  4. Environmental Cleaning:

    • Routine disinfection of surfaces in patient care areas.

  5. Respiratory Hygiene:

    • Encourage coughing into tissues and maintaining distance.

  6. Isolation Precautions:

    • Standard, airborne, droplet, and contact precautions based on patient conditions.

5. Biomedical Waste Management Guidelines 

Categories of Waste

  1. Infectious Waste: Items contaminated with blood, body fluids, or infectious agents.
  2. Sharp Waste: Needles, syringes, and surgical blades.
  3. Pharmaceutical Waste: Expired or unused medications.
  4. Chemical Waste: Disinfectants, lab reagents.

Waste Segregation and Disposal

  1. Color-Coded Bags:

    • Yellow: Infectious and pathological waste.
    • Red: Contaminated plastics like IV sets.
    • Blue/White: Glassware and sharps.
    • Black: Non-hazardous waste.

  2. Treatment Methods:

    • Autoclaving or Incineration: For infectious and pathological waste.
    • Chemical Disinfection: For liquid waste.
    • Deep Burial: For waste in rural areas.

  3. Monitoring and Documentation:

    • Maintain logs of waste generated and treated.


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