Iodine: A Very Old and Efficient Bactericidal, Fungicidal, Virucidal and Sporicidal Agent

Among the many germicidal agents, iodine counts as one of the oldest, having been in use since the mid-1800's, or for over one and a half century. It is also one of the most powerful, being highly effective against all kinds of bacteria, most of the different types of fungi, and some of the many virulent substances.

An element which belongs to the halogen group, iodine is distinctive for its bluish-black color and metallic refulgence. While it dissolves readily in alcohol, it is only partially soluble in water. When heated, it gives forth corrosive fumes of a rich violet color.

Iodine is traditionally used as a germicidal agent in a form many people are familiar with - tincture of iodine. At least three other similar preparations, each containing specific iodine proportions, are available: 7% iodine and 5% potassium iodide mixed in 83% alcohol; 5% iodine combined with 10% potassium iodide in aqueous solution; and 2% iodine and 2% sodium iodide blended in alcohol. Another form of iodine preparations called iodophors (iodine mixed with certain surface-active agents, such as polyvinylpyrrolidones - which function as solubilizing agents for the iodine) possess, apart from their distinction of similarly being effective germicidal agents, the added features of being less-irritating and non-staining.

The uniqueness of iodine as a bactericidal agent lies in its being able to act effectively against not just some but all kinds of bacteria. Apart from this, it also has sporicidal activity; here though, the rate at which the spores are destroyed is prominently affected by certain conditions under which the spores are exposed, examples of which are the amount of organic material and the extent of dehydration.

Iodine is also recognized for its powerful antiseptic properties; iodine solutions, which are primarily used for the disinfection of skin, are among the best disinfectants available. Other iodine preparations are useful and completely effective for other disinfecting purposes, including disinfection of water and air, the latter with the use of iodine vapor. In dining establishments, iodine-based preparations are used to sanitize utensils.

The mechanical action by which iodine puts forth its germicidal activity is not well defined, although there are suggestions that the mechanism may involve the introduction of halogen into tyrosine (an amino acid) units of enzymes and other cellular proteins requiring this same amino acid for activity. It has likewise been suggested that the germicidal activity of iodine may partly be responsible for iodine's being also an effective oxidizing agent. [Read the Original Article]