Antiseptics and Disinfectants - Practice Questions & MCQ

The chemicals used for sterilisation are classified under two headings:

1. Antiseptics: The term 'septic' is derived from the Greek work septikos which means putrify or rot. In medicine, it indicates the state of being infected with pus forming organisms. Anti-infective agents which are applied locally, i.e., applied directly to the skin wounds, cuts, ulcers and diseased skin surfaces, etc., are known as antiseptics.
   Chemical substances which prevent the growth of microorganisms and kill them but are not harmful to the living human tissues are called antiseptics. Some common examples of antiseptics are Dettol, savlon, acriflavin, gentian iodine, iodoform, potassium permanganate, etc.
2. Disinfectants: These substances kill the microorganisms or stop their growth but are harmful to the human tissues. These are used for sterilisation of inanimate objects like instruments, utensils, toilets, drains, floors, living tissues and cannot be used on the skin. Examples are phenol, methyl phenols, hydrogen peroxide, chlorine, bleaching powder, etc.

The same substances can act as antiseptics or disinfectants depending upon the concentration of the substance in the solution. In smaller concentrations, it is an antiseptic while in higher concentrations it becomes a disinfectant. For example, 0.2% solution of phenol acts as an antiseptic and its 1% solution is a disinfectant.