ANTIMICROBIAL AGENTS

LEARNING

ü  Antimicrobial Agents

ü  Antiseptic

ü  Disinfectant

ü  Germicide

ü  Germistatic

ü  Mechanism of action of anti-microbial agents

o   Oxidation

o   Halogenations

o   Protein precipitation  

What are Antimicrobial Agents?

·         The chemical substances which can kill or inhibit the growth of microorganisms are called Antimicrobial agents.

·         Examples of Inorganic Antimicrobial agents most widely used are-

·         Bleaching powder, Hydrogen peroxide, Potassium permanganate, Sodium hypochlorite, Iodine, Silver nitrate, Mercury, mercuric oxide, Sodium perborate.

Classification

Depending upon the activity of antimicrobial agents these may be classified as;

1. Antiseptics

·         Any agent that either kill or inhibit the growth of microorganism (bacteria, fungi, virus, Protozoa) but these are only applied in the living tissue.

·         Antiseptic agents oppose the sepsis, putrefaction or decay of the damaged or exposed tissue by inhibiting microbial multiplication and metabolic activities or by killing the pathogenic microorganism.

·         This type of agents may be used in the form of mouth washes, soaps, deodorants, throat and nasal sprays and vaginal douches.

2. Disinfectants

·         Any agent that either kill or inhibit the growth of microorganism (bacteria, fungi, virus, Protozoa) but these are only applied on inanimate objects(instruments, rooms, floor, rooms, equipment, Pond, river)

·         They are non-selective and destroy non pathogens .also these are irritant and corrosive to the skin or tissue.

3. Germicide -(cide-Kill, latin caeder means to kill)

·         These are the agents that kill the microorganism. The different terminology may be used for specific action of these agents.

·         Bactericide-kill bacteria, fungicide-kill fungi, virucide – kill virus

4. Germistatic – (stat – standing till, Greek word stasis)

·         These are the agents that do not kill microorganism but inhibit their growth.

·         The term bacteistatic, fungistatic are used against the respective microorganism.

5. Sanitizers

·         The antimicrobial agents which are used to maintain general public health standards.

·         Characteristic of an Antimicrobial agents

o   Should have antiseptic and germicidal activity.

o   Should have faster onset of action.

o   Should have better therapeutic index.

o   Should not cause local cellular damage.

o   Should not interfere with body defence mechanism.

o   Should not show the systemic toxicity.

o   Should have broad spectrum activity against bacteria, fungus, virus, and protozoa.

How the Inorganic antimicrobial agents are act?

Mechanism of action of Inorganic Antimicrobial agents

·         Inorganic antimicrobial agents are shown their action any of the following three mechanism of action.

1. Oxidation

2. Halogenations

3. Protein precipitation

1. Oxidation

·         Oxidative mechanism showing agents are generally non metals and certain types of anions.

·         Example: hydrogen peroxide, metal peroxides, permanganates, halogens (chlorine, iodine) and certain oxo halogen anions.

·         As the microbial proteins and enzymes are vital for the growth or survival of the microorganism.

·         This types of agents are oxidised the reducing group (sulpha hydryl group-SH present in cysetein amino acid) of microbial proteins or enzymes, which leads to form a disulphide bridge in the protein and also changes it conformation (shape) and function.

·         The overall changes of function of specific protein responsible for destruction of microorganism.