7 Antimicrobial Activity and Action of Silver

This chapter discusses antimicrobial activity and action of silver. Silver and its compounds have long been used, in one form or another, as antimicrobial agents. The silver compound of major therapeutic interest at the present time is silver sulphadiazine. Many in healthcare know that other silver compounds are still in use. It is worth stating that the treatment of ophthalmia neonatorum was revolutionized by the instillation of silver derivatives into the eyes of new-born sufferers. Several factors influence the antimicrobial activity of silver salts. Silver has a marked tendency to adsorb to surfaces and bactericidal activity is reduced in the presence of phosphates, chlorides, sulphides and hard water. Activity is increased as the temperature is raised and is pH-dependent, increasing with increasing pH. Sodium thioglycollate has been recommended as a suitable neutralizing agent for use in bactericidal testing although other SH compounds also fulfil this role. Silver, one of the native metals and second only to gold in its stability amongst the metals of antiquity, has provided several therapeutic agents which have been employed since the beginning of recorded history. These agents range from the metal itself, its salts and complexes with proteins and other macromolecules to the latest, silver sulphadiazine (AgSD).