Disinfectants, Antiseptics and Antibiotics

Disinfectants, Antiseptics and Antibiotics

Disinfection is the elimination of microorganisms from inanimate objects or surfaces. The term disinfectant is used for an agent used to disinfect inanimate objects or surfaces but is generally toxic to use on human tissues. Antiseptic refers to an agent that kills or inhibits growth of microorganisms but is safe to use on human tissues.

Antibiotics produced by microorganisms which kill or inhibit the growth of other microbes.

Following Table gives few examples of antimicrobial chemical agents that destroy unwanted microorganisms.

Basic terms used in chemical control of microorganism are mentioned in Table 3.1 and Table 3.2 Describes the difference between Bactericidal and Bacteriostatic agents.

Basic terms used in Chemical sterilization

Disinfection: The selective elimination of certain undesirable microorganisms to prevent their transmission directed against their metabolism or structure; applies to the use directly on inanimate objects.

Antisepsis: Prevention of the growth or activity of microorganisms by inhibition or killing; applies to the use of chemicals on living tissue

-cide: Suffix used to denote agents, usually chemical, that kill. Commonly used terms are bactericide, fungicide, virucide, and algicide. The term germicide is used if the agents kill pathogens but not necessarily spores. An agent that kills bacterial spores is a sporicide.

-static: Suffix used to denote agents, usually chemical, that prevents growth but do not necessarily kill the organism or bacterial spores. Commonly used terms include bacteriostatic and fungistatic. 

Table 3.2: Difference between Bactericidal and Bacteriostatic

Bactericidal

• Bactericidal refers to agents that kill bacteria

• Action is irreversible

• Inhibit the cell wall formation of bacteria

• Do not work with the immune system of the host

• Minimal Bactericidal Concentration (MBC) refers to the concentration of the drug required to kill 99.99% of the bacterial population

• Examples include betalactam antibiot- ics, cephalosporins, and vancomycin

Bacteriostatic

• Bacteriostatic refers to agents that prevent the growth of bacteria

• Action is reversible

• Inhibit DNA replication and protein synthesis of bacteria   

• Work with the immune system of the host to prevent the growth and reproduction of ­bacteria

• Minimal Inhibitory Concentration (MIC) is the ­minimum drug concentration which inhibits the bacterial growth

• Examples include tetracyclines, spectinomycin, chloramphenicol,­ sulfonamides, etc.