DISINFECTION AND ANTISEPSIS

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Disinfection

Disinfection is defined as the killing, elimination or removal and the inhibition of microbial growth on inanimate objects (i.e. on non-living surfaces or objects). It is the act of removing infection or infective agents (capable of causing infection) on inanimate objects. Disinfection is usually carried out with chemical agents generally known as disinfectants. A disinfectant is an antimicrobial agent that disinfects (i.e. removes or destroys microorganisms). It is only used on non-living objects such as hospital equipment/instrument, door handles, floors, sinks, walls, desks, laboratory bench and at home to disinfect surfaces and objects likely to harbour microbes. The act of disinfection using disinfectants is employed in virtually all non-living surfaces and objects that may act as means via which pathogenic microorganisms is being transmitted within a given area. Sodium hypochlorite (or bleach) and chlorine (used as water disinfectants in water treatment plants) are typical examples of disinfectants used for most industrial and domestic applications. Other forms of disinfectants are also commercially available in the market (as germicides), and these are mainly used for domestic purposes.

Though non-selective in their mode of action and are primarily used on inanimate objects or surfaces, disinfectants are very ineffective in killing or inhibiting the growth of vegetative or viable microorganisms. However, they are not effective in the killing of spores formed by microbes including those of bacteria, fungi and enveloped viruses. Prions (which are infectious particles without nucleic acids) are also resistant to the onslaught of disinfectants. After disinfection, it is noteworthy to know that some microorganisms (inclusive of those that form spores) may still remain active after the action of the disinfectants and even in the face of their onslaught because they have developed resistance to the antimicrobial agents in use. It is therefore advisable for hospitals, industries and other users of disinfectants to review from time to time their disinfectant policies and try as much as possible to alternate the brands or types of disinfectants they use at any given time. This will go a long way in reducing the level of resistance mounted by pathogenic microorganisms against these agents. Using a particular disinfectant every time for a long period gives microbes the opportunity to develop resistance towards it due to selective pressure. Policies bothering on disinfectant usage should be strictly adhered to by all those that use these antimicrobial agents in order to ensure an effective disinfection process at each point in time.   

Antisepsis

Antisepsis is defined as the process of killing or inhibiting the growth of microorganisms on animate (or living) things such as the human body. Just as disinfectants are used to accomplish disinfection, antiseptics are the chemical agents used to carry out antisepsis procedures. Antiseptics kill or inhibit the growth of pathogenic microorganisms in or on living tissue. They are used to prevent sepsis or putrefaction (i.e. decay) on living tissues such as in wound infections. Antiseptics are usually applied to the external body surfaces of living organisms (e.g. the skin) because they are less-irritable and not as toxic as disinfectants (which are strictly used on non-living surfaces and objects). Iodine tincture and alcohol (e.g. methylated spirit) are some of the commonly used antiseptics in the homes and hospital environment. Antiseptics are commercially available in the market with different brand names. They all serve the same purpose of killing or inhibiting microbial growth on living tissues even though their mode of action may vary.

Antiseptics are important chemicals used to reduce microbial load both at home, in the industries and even in the hospital. Doctors, nurses and other healthcare givers apply antiseptic solutions or agents on their hands and skin prior to  a surgical operation or on other invasive treatment procedure (e.g. administration of injection) in order to reduce the level of microbial load on their body, and which could go on to infect their patients. The discovery of antiseptics and their application in medical practice by Joseph Lister at a time when mortality following post-operative operations was alarming helped to control and prevent microorganisms from infecting wounds because microorganisms were at the time contaminating injuries after surgical operation. Lister’s procedure is still used in medical practice even till date as an important infection control and prevention measure in the hospital.

FURTHER READING

Ashutosh Kar (2008). Pharmaceutical Microbiology, 1st edition. New Age International Publishers: New Delhi, India. 

Block S.S (2001). Disinfection, sterilization and preservation. 5th edition. Lippincott Williams & Wilkins, Philadelphia and London.

Courvalin P, Leclercq R and Rice L.B (2010). Antibiogram. ESKA Publishing, ASM Press, Canada.

Denyer S.P., Hodges N.A and Gorman S.P (2004). Hugo & Russell’s Pharmaceutical Microbiology. 7th ed. Blackwell Publishing Company, USA. Pp.152-172.

Finch R.G, Greenwood D, Norrby R and Whitley R (2002). Antibiotic and chemotherapy, 8th edition. Churchill Livingstone, London and Edinburg.

Russell A.D and Chopra I (1996). Understanding antibacterial action and resistance. 2nd edition. Ellis Horwood Publishers, New York, USA.

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