Although microorganisms are beneficial and necessary or human well-being, microbial activities have undesirable consequences such as food spoilage and disease. To minimize their destructive effects, it is essential to kill a wide variety of microorganisms orinhibit their growth. The goal is twofold, to destroy pathogens and prevent their transmission and to reduce or eliminate microorganisms responsible for the contamination of water, food and other substances.

Sometimes it is necessary to eliminate the microorganisms completely from an object, whereas sometimes only partial destruction may be required in other situations. The control of microbial populations on inanimate objects, like eating utensils, surgical instruments is of considerable importance. Sterilization – is the process by which all living cells, viable spores, viruses, and viroids are either destroyed or removed from an object or habitat. When sterilization is achieved by a chemical agent, the chemical is called a sterilant. Disinfection – is the killing, inhibition or removal of microorganisms that may cause disease. Disinfectants are agents, usually chemical used to carry out disinfection and does not necessarily sterilise an object because viable spores and few microorganisms may remain. Sanitization is closed related to disinfection. It is sometimes necessary to control microorganisms on living tissue with chemical agents. Antisepsis – is the prevention of infection or sepsis and is accomplished with antiseptics. These chemical agents are applied to living tissue and they prevent infection by killing or inhibiting pathogen growth or they reduce the total microbial population. Substances that kill organisms often have the suffix – cide, germicide – kills pathogens but not necessary endospores. A disinfectant or antiseptic can be effective against a specific group and may be called a bactericide, fungicide, algicide and viricide. Other chemicals do not kill, but they do prevent growth, and if these are removed, growth will resume. Their names end in – static like, bacteriostatic and fungistatic.

Conditions influencing the effectiveness of antimicrobial agent activity:

The efficiency of an antimicrobial agent is not simple and is affected by some factors as stated below.

Population size: A larger microbial population requires a longer time to die than a smaller one as an equal fraction of it is killed during each interval.