ABSTRACT
This chapter describes the antimicrobial activity of silver ions and Ag NPs and silver toxicity to human cells will be presented. The molecular basis and mechanism of silver resistance were first described for a Salmonella enterica serovar Typhimurium strain that caused the closure of the Massachusetts General Hospital burn ward after septicaemia and death in three patients and is still today the best-characterised. The plasmidic region responsible for silver resistance comprises the silCFBA(ORF105aa)PRSE gene cluster, and eight out of the nine gene products were primarily characterised based on homology to the E. Although studies exploring silver resistance in clinical bacteria showed a rather low prevalence of sil genes and limited clinically significant phenotypic expression, recently, two strains resistant to clinically relevant Ag concentrations were isolated from patients in a tertiary care facility. The main exposure routes of silver compounds are through dermal contact, oral administration and inhalation.
