Disinfectants in microbiology , bpharm 2nd year

disinfectants

1. DISINFECTANTS
CLASSIFICATION AND MODE OF ACTION OF DISINFECTANTS

2. DISINFECTANTS
•Disinfectants are chemical substances or compounds used to inactivate or
destroy microorganisms on inert surfaces.
•Process that eliminates many or all pathogenic microorganisms, except
bacterial spores, on inanimate objects.
•Usually disinfectants are bactericidal. Occasionally it maybe bacteriostatic.

3. IDEAL PROPERTIES OF DISINFECTANT
•Broad Spectrum of Antimicrobial Activity.
•Non-Toxic and Non-Corrosive.
•Chemically stable during storage.
•Odorless or have a pleasant odor.
•It should work well in both acidic and alkaline media.
•Quick action is essential for effective microbial control.
•The disinfectant should be soluble in both water and lipids.
•Cost-effectiveness (Economical).

4. CLASSIFICATION OF DISINFECTANTS
Based on Consistency:
Disinfectants can be classified based on their physical form or
consistency:
•Liquid Disinfectants: These include alcohols (such as ethanol and
isopropanol) and phenols.
•Gaseous Disinfectants: Examples include formaldehyde vapor
and ethylene oxide.

5. Based on Spectrum of Activity:
Disinfectants are categorized into three levels based on their effectiveness
against various microorganisms:
•High-Level Disinfectants: These are effective against a broad range of
microorganisms, including bacterial spores.
•Intermediate-Level Disinfectants: They work against most bacteria, fungi,
and viruses but may not eliminate bacterial spores.
•Low-Level Disinfectants: These have limited activity and are primarily
effective against vegetative bacteria and some viruses

6. Based on Mechanism of Action:
Disinfectants act through different mechanisms to destroy or inhibit microorganisms:
•Action on Membrane: Some disinfectants disrupt cell membranes, leading to cell
death.
•Denaturation of Cellular Proteins: Disinfectants cause protein denaturation,
rendering essential cellular proteins nonfunctional.
•Damage to Nucleic Acids: Certain disinfectants target DNA or RNA, preventing
replication.
•Oxidation of Essential Sulfhydryl Groups of Enzymes:Oxidizing agents interfere
with enzyme function.
•Alkylation of Amino-, Carboxyl-, and Hydroxyl Groups: Alkylating agents modify
functional groups in proteins and nucleic acids.

7. Disinfectants are used to inactivate pathogens by:
•Destroying Cellular Structures: Disinfectants disrupt the cellular structure of
microbes, rendering them unable to grow or reproduce.
•Metabolism Disruption: They interfere with microbial metabolism, making it
impossible for the microorganisms to thrive.

8. MODE OF ACTION OF DISINFECTANTS
The primary function of disinfectants is to act on microorganisms. Their action
can be categorized in two ways:
•Growth Inhibition (Bacteriostasis, Fungistatic): Disinfectants inhibit the
growth of microorganisms without necessarily killing them. This effect prevents
further multiplication.
•Lethal Action (Bactericidal, Fungicidal, or Virucidal): The main objective of
disinfectants is to cause lethal action, effectively killing the microorganisms.

9. APPLICATIONS OF DISINFECTANTS
Common chemical disinfectants along with their applications:
1.Alcohols:
Examples: Ethyl alcohol (ethanol) and isopropyl alcohol (isopropanol).
Applications:
•Healthcare Settings: Used for surface disinfection, hand sanitization, and medical
equipment sterilization.
•Household: Found in hand sanitizers, surface wipes, and cleaning products.
•Water Treatment: Used for water disinfection

10. 2. Chlorine and Chlorine Compounds:
Examples: Sodium hypochlorite (bleach), calcium hypochlorite, and
chlorine gas.
Applications:
•Water Treatment: Chlorine is commonly used to disinfect drinking water and
swimming pools.
•Healthcare Facilities: Used for surface disinfection and sterilization.

11. 3. Hydrogen Peroxide:
Applications:
•Household: Used for wound cleaning and as a surface disinfectant.
•Healthcare: Used for wound care, sterilization, and surface disinfection.
•Water Treatment: Sometimes used for water disinfection.
4. Iodophors:
Applications:
•Healthcare: Used for skin disinfection before surgery and as an antiseptic.
•Veterinary: Used for wound care in animals.
•Water Treatment: Rarely used due to potential toxicity.

12. 5. Quaternary Ammonium Compounds (Quats):
Examples: Benzalkonium chloride, cetylpyridiniumchloride.
Applications:
•Household Cleaners: Found in disinfectant wipes, sprays, and surface cleaners.
•Healthcare Facilities: Used for surface disinfection.
•Swimming Pools: Used to control microbial growth.
The choice of disinfectant depends on the specific application, the type of
microorganisms present, and the intended level of disinfection.