Microbial Control: Sterilization Methods

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Questions and Answers

Which antiseptic is known for having a broad antimicrobial activity and residual effect?

  • Alcohol
  • Iodophor (Betadine)
  • Triclosan
  • Chlorhexidine (correct)

What is a significant disadvantage of using alcohol as an antiseptic?

  • It requires no cleaning of organic matter.
  • It has a residual effect.
  • It is toxic to tissues.
  • It causes dryness to the skin. (correct)

Which of the following antiseptics is noted for being less toxic to tissues than other iodine solutions?

  • Iodophors (Betadine) (correct)
  • Alcohol
  • Chlorhexidine
  • Triclosan

What sets Triclosan apart from other antiseptics mentioned?

<p>It is primarily used in deodorant soaps and toothpaste. (C)</p> Signup and view all the answers

What is a key factor to consider before applying alcohol as an antiseptic?

<p>The skin should be cleaned of organic matter first. (A)</p> Signup and view all the answers

What is a key advantage of plasma gas sterilization?

<p>It is efficient and produces non-toxic byproducts. (D)</p> Signup and view all the answers

Which type of disinfectant is most appropriate for surgical equipment that cannot withstand sterilization?

<p>High-level disinfectant (D)</p> Signup and view all the answers

What is the main purpose of disinfection?

<p>To eliminate disease-causing microorganisms from non-living objects. (D)</p> Signup and view all the answers

Which method of disinfection uses moist heat?

<p>Pasteurization (A)</p> Signup and view all the answers

Which chemical sterilization agent is most commonly used for surgical instruments?

<p>Glutaraldehyde (D)</p> Signup and view all the answers

What is the effectiveness of disinfection on bacterial spores?

<p>Some resistant bacterial spores may survive disinfection. (B)</p> Signup and view all the answers

Which of the following is a characteristic of intermediate-level disinfectants?

<p>They are used on surfaces unlikely to have spores. (D)</p> Signup and view all the answers

Which chlorine compound characteristic is correct?

<p>Chlorine is a rapid bactericidal agent. (B)</p> Signup and view all the answers

What is the main purpose of sterilization, disinfection, and antisepsis?

<p>To control infections (D)</p> Signup and view all the answers

Which method is NOT considered a physical sterilant?

<p>Hydrogen peroxide vapour (A)</p> Signup and view all the answers

Which of the following is a characteristic of the boiling method of sterilization?

<p>Inexpensive and widely used (C)</p> Signup and view all the answers

What type of sterilant is ethylene oxide?

<p>Chemical sterilant (B)</p> Signup and view all the answers

Why is boiling considered inefficient as a sterilization method?

<p>It does not kill all microbes (C)</p> Signup and view all the answers

Which of the following is NOT a gas vapor sterilant?

<p>Chlorine dioxide (D)</p> Signup and view all the answers

What type of items is ethylene oxide gas primarily used to sterilize?

<p>Sensitive items like catheters (D)</p> Signup and view all the answers

Which of the following methods requires prolonged exposure times to be effective?

<p>Chemical sterilants (C)</p> Signup and view all the answers

What is the primary use of intermediate-level disinfectants?

<p>To disinfect semi-critical instruments (B)</p> Signup and view all the answers

Which of the following is true about alcohols as disinfectants?

<p>They do not act against bacterial spores (C)</p> Signup and view all the answers

What is the main function of tincture of iodine?

<p>It precipitates proteins and oxidizes essential enzymes. (B)</p> Signup and view all the answers

Which statement describes phenolic compounds?

<p>They are not effective at lower temperatures. (A)</p> Signup and view all the answers

What type of disinfectant is used for treating non-critical instruments?

<p>Low-level disinfectants (C)</p> Signup and view all the answers

Which of the following organisms is known to be resistant to quaternary ammonium compounds?

<p>Trichophyton (D)</p> Signup and view all the answers

What is a characteristic of iodophor compounds?

<p>They complex iodine with a carrier. (A)</p> Signup and view all the answers

What is the primary limitation of low-level disinfectants against certain organisms?

<p>They are ineffective against mycobacteria. (C)</p> Signup and view all the answers

Flashcards

Sterilization

The complete destruction of all microbial life, including resistant forms like spores.

Disinfection

Methods used to eliminate or kill most microorganisms, but not necessarily all spores.

Antisepsis

A process that reduces the number of microbes on living tissue, often used to prevent infections during surgery or medical procedures.

Main Purpose of Microbial Control

The primary goal of sterilization, disinfection, and antisepsis is to control the spread of infections.

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Physical Sterilization Methods

Methods like heat (e.g., steam under pressure), radiation, or filtration that physically destroy microbes.

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Chemical Sterilization Methods

Chemicals that destroy microbes.

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Ethylene Oxide

A gas that is commonly used to sterilize medical equipment.

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Glutaraldehyde

A highly effective sterilant, but typically used on heat-sensitive medical instruments.

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Disinfectants

Substances used to destroy microorganisms on non-living objects.

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Plasma Gas Sterilization

A type of sterilization using plasma gas, which is effective in destroying microorganisms by targeting their essential components like enzymes and DNA.

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Chemical Sterilization

A method of sterilization that utilizes chemicals to kill microorganisms.

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High-level Disinfectants

Used for items that can't withstand sterilisation, such as instruments with plastic parts. Examples include moist heat and chemical disinfectants.

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Intermediate Level Disinfectants

Used to clean surfaces or instruments with low risk of spore contamination. Examples include alcohols.

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Low-level Disinfectants

Used to treat non-critical devices like blood pressure kits and stethoscopes. Examples include quaternary ammonium compounds.

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Alcohols

Commonly used intermediate-level disinfectants that are effective against many types of bacteria, mycobacteria, some fungi, and certain viruses.

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Iodine

A powerful disinfectant that is highly reactive and can destroy most organisms, including spores. It works by damaging proteins needed for microbial survival.

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Iodophors

Iodine combined with a carrier molecule for a gentler and more stable form. Still effective against a wide range of microbes, including spores.

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Phenolic compounds

Disinfectants that are active against bacteria with high lipid content in their cell walls, like Mycobacteria. However, they have limited activity against spores and certain viruses.

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Quaternary ammonium compounds

A type of low-level disinfectant that can be bacteriostatic at low concentrations and bactericidal at higher concentrations. However, they are ineffective against certain bacteria, viruses, spores, and fungi.

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Spore-forming bacteria

Bacteria that are particularly resistant to disinfectants and require more rigorous sterilization methods to eliminate.

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Triclosan

A group of chemicals that kill bacteria, but not spores, and are often found in soaps and toothpaste.

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Alcohol as an antiseptic

Alcohols are effective against most microbes, but not spores. They're non-toxic, but can dry out skin and are easily inactivated by organic matter.

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Iodophors (Betadine)

Iodophors are stable, non-toxic to tissues, and effective against many microbes but can irritate skin.

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Chlorhexidine

Chlorhexidine is broad-spectrum, has residual activity (lasts longer), but kills microbes slower than alcohol.

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Study Notes

Microbial Control: Sterilization, Disinfection, and Antisepsis

  • The main purpose of sterilization, disinfection, and antisepsis is controlling infections.
  • Sterilization eliminates all forms of microbial life, including spores. This is achieved through methods like gas vapor, physical, or chemical sterilants. It aims to preserve treated products safely at room temperature.
  • Physical sterilants include flaming, steam under pressure, filtration, ultraviolet radiation, and ionizing radiation.
  • Chemical sterilants include per acetic acid and glutaraldehyde.
  • Gas vapor sterilants include ethylene oxide, formaldehyde, hydrogen peroxide vapor, and plasma gas.
  • Boiling is an inefficient method of sterilization as it only kills vegetative organisms at 100°C. Spores remain viable.
  • Chemical methods of sterilization include ethylene oxide, formaldehyde, hydrogen peroxide vapor, and plasma gas.
  • Ethylene oxide gas is used to sterilize sensitive items like catheters, plastic packaging, and equipment with integrated electronics.
  • Plasma gas sterilization effectively destroys microorganisms' components, like enzymes, nucleic acids, and DNA.
  • Chemical sterilization in an automated machine is used for medical, surgical, and dental instruments (e.g., endoscopes, bronchoscopes). Aldehydes (e.g., glutaraldehyde) are used to sterilize surgical instruments.

Disinfection

  • Disinfectants destroy microorganisms living on non-living objects.
  • Disinfection is less effective than sterilization, as it does not necessarily kill all microorganisms, especially resistant bacterial spores.
  • Disinfection aims to make surfaces free of disease-causing microorganisms.
  • Disinfectant levels vary: high, intermediate, and low.
  • High-level disinfectants treat items that can't withstand sterilization (e.g., surgical equipment with plastic components). Examples include moist heat and chemicals like glutaraldehyde, hydrogen peroxide, and peracetic acid and chlorine compounds.
  • Intermediate-level disinfectants are used where contamination with bacterial spores is unlikely. Examples include alcohols, iodophor compounds, and phenolic compounds (e.g., phenol, carbolic acid). They're used on semi-critical instruments like flexible fiber optic endoscopes, laryngoscopes, vaginal specula, and anesthetic breathing circuits.
  • Low-level disinfectants treat non-critical instruments and devices (e.g., blood pressure cuffs, electrocardiogram electrodes, and stethoscopes). Quaternary ammonium compounds are an example.

Antisepsis

  • Antiseptics reduce the number of microbes on living tissue, unlike disinfectants which act on non-living surfaces.
  • They aim to reduce the possibility of infection or sepsis on living tissues.
  • No sporicidal action is involved.
  • Selected antiseptic agents include alcohols (e.g., 70-90% ethanol and isopropyl alcohol), iodophors (e.g., betadine), chlorhexidine, and triclosan.
  • Alcohol is effective against most organisms except spores. However, it has the disadvantage of being drying to the skin and being inactivated by organic matter.

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