Control and Destruction of Microbes


Q1.Define sterilization. Explain different methods of sterilization in detail.

Ans:Definition of Sterilization

Sterilization is the process of eliminating or destroying all forms of microbial life, including bacteria, viruses, fungi, and spores, from a surface, fluid, medication, or biological culture medium. It ensures that an object or substance is completely free from any living microorganisms.

Different Methods of Sterilization

There are several methods of sterilization, each suitable for different materials and purposes. The main methods include:

1. Heat Sterilization

  • Moist Heat Sterilization (Autoclaving): Uses steam under pressure (usually at 121°C and 15 psi for 15-20 minutes) to kill microorganisms. It is effective against all types of microbes including spores.
  • Dry Heat Sterilization: Involves hot air ovens operating at 160-170°C for 2 hours or 180°C for 30 minutes. It is used for materials that can withstand high temperatures but are damaged by moisture.

2. Chemical Sterilization

  • Ethylene Oxide Gas: Used for sterilizing heat-sensitive equipment. It penetrates materials and kills microorganisms by alkylating their DNA.
  • Formaldehyde: Used in gaseous or liquid form for sterilizing instruments and rooms.
  • Hydrogen Peroxide Plasma: A low-temperature sterilization method using hydrogen peroxide vapor and plasma.

3. Radiation Sterilization

  • Ultraviolet (UV) Radiation: Used for surface sterilization and air sterilization. It damages the DNA of microorganisms.
  • Gamma Radiation: Used for sterilizing disposable medical equipment and pharmaceuticals. It penetrates deeply and kills microbes.

4. Filtration Sterilization

  • Used for heat-sensitive liquids and gases. It involves passing the fluid through a filter with pores small enough (usually 0.22 micrometers) to remove microorganisms.

5. Other Methods

  • Gas Plasma Sterilization: Uses ionized gas to sterilize equipment at low temperatures.
  • Chemical Disinfectants: Though primarily for disinfection, some chemicals at specific concentrations and exposure times can achieve sterilization.

Each method is chosen based on the nature of the material to be sterilized, the type of microorganisms present, and practical considerations such as cost and safety.



Previous Year Questions (As per INC & ANC Syllabus)

Long Questions (5–10 Marks)


Q.Define sterilization. Explain different methods of sterilization in detail.

Q.Differentiate sterilization and disinfection with examples.

Q.Describe physical methods used for control of microorganisms.

Q.Explain chemical methods of disinfection and sterilization.

Q.Discuss the role of autoclaving in hospital infection control.

Q.Explain methods of destruction of microbes by heat.

Q.Describe moist heat and dry heat sterilization methods.

Q.Define antiseptics and disinfectants. Explain their uses in hospitals.

Q.Discuss biomedical waste management in prevention of infection.

Q.Explain standard precautions followed in hospitals for infection control.

Q.Describe the principles of asepsis.

Q.Explain the preparation and care of sterile articles.

Q.Define fumigation and explain its uses.

Q.Explain methods of disposal of infectious waste.

Q.Discuss nurse’s responsibility in sterilization and disinfection procedures.


Short Notes (3–5 Marks)


Sterilization

Disinfection

Antiseptics

Disinfectants

Autoclave

Hot air oven

Boiling

Pasteurization

Radiation sterilization

Fumigation

Incineration

Biomedical waste management

Surgical asepsis

Medical asepsis

Universal precautions

Chemical sterilization

Steam sterilization

UV rays

Filtration

Cross infection prevention


Very Short Questions 


Define sterilization.

Define disinfection.

What is antiseptic?

What is disinfectant?

Name one method of dry heat sterilization.

Name one method of moist heat sterilization.

What is autoclave?

What temperature is used in autoclaving?

Define pasteurization.

What is fumigation?

Name one chemical disinfectant.

What is biomedical waste?

What color bag is used for infectious waste?

Define asepsis.

What is incineration?

Name one radiation used for sterilization.

What is filtration?

Define surgical asepsis.

Define medical asepsis.

What is contamination?