Antimicrobial Agents - An Overview

What are Antimicrobial Agents?

Infections and diseases may be caused by the different type of organisms like bacteria, fungi and virus etc., in humans and animals. The drug used to prevent the pathogenicity of microorganism is called an antimicrobial agent.

Examples: Antibiotics, antiseptics, and disinfectants.

Antimicrobial agents are used to prevent infections and diseases caused by pathogens. Different types of antimicrobial drugs are commonly available. These are as follows:

  1. Antibacterial drug: A drug which is used to inhibit the pathogenic activity of bacteria is called as antibacterial drugs. Example: Zithromax.

  2. Antifungal drug: A drug which is used to prevent the fungal activity in the host is called an antifungal drug. Example: Miconazole

  3. Antiviral agent: A drug which is used to stop the pathogenic action of a virus is called as antiviral agents. Example: Tamiflu.

  4. Antiparasitic drug: A drug which is used to prevent the growth of pathogenic parasites. Example: Anthelmintics


Antibiotics are the substances which are derived from one microorganism in order to kill another microorganism. Antibiotics are effective against bacterial, fungal and parasitic infections. But, antibiotics are not helpful against viral infections.

The development of chemical synthesis has helped to produce the synthetic components which act as an antimicrobial agent against the pathogenic bacteria. These synthetic components are also called as antibiotics. Pathogenic bacteria can be killed by synthetic components at low concentrations. Examples: Ampicillin and amoxicillin.

In 1908, a German bacteriologist, Paul Ehrlich had developed a synthetic component from an arsenic-based structure for the treatment of syphilis, which is called as arsphenamine or salvarsan.

Then, in 1929, Alexander Fleming discovered Penicillin from the fungus Penicillium notatum. Penicillin is used to treat different type of bacterial infections.

Two types of antibiotics are commonly available. These are as follows:

  1. Bactericidal antibiotics: These antibiotics are have killing effects on bacteria. Example: Penicillin, Aminoglycosides, Ofloxacin.
  2. Bacteriostatic antibiotics: These antibiotics have an inhibitory effect on bacteria. Example: Erythromycin, Tetracycline, Chloramphenicol.

Depends on the spectrum of action, antibiotics are further classified into three types. These are as follows:

  1. Broad-spectrum antibiotics: These antibiotics are widely used to kill or inhibit the Gram-positive and Gram-negative bacteria. Example: Chloramphenicol
  2. Narrow spectrum antibiotics: These antibiotics are widely effective against specific groups of bacteria. Example: Penicillin G
  3. Limited spectrum antibiotics: These antibiotics are effective against a single organism or a single disease. Example: Dysidazirine.

Antiseptics and Disinfectants

Antiseptics and disinfectants are the chemical components which are used as antimicrobial agents.

Antiseptics are applied to the injured tissues, cuts, and infected skin surfaces. Antiseptics are not prescribed to be taken orally. A few examples are given below:

  1. Dettol: It is a mixture of chloroxylenol and terpineol. It is used to apply in the wounds.
  2. Iodine tincture and iodoform – It has very good antiseptic properties.
  3. Boric acid – It is used as an antiseptic agent for eyes.

Disinfectants are used to destroy the pathogenic microorganisms in the nonliving objects such as floors and drainage systems.

Example: Chlorine and sulphur dioxide at low concentration.