Clinical studies designed to evaluate the suitability of new devices or products containg silver, commonly focus upon the efficacy of the silver ion (Ag+) release in inhibiting opportunistic and nosocomial pathogens. Silver effectively controls most Gram-positive, Gram-negative and fungal infections in wounds, and Ag+ ions released from metallic silver particles (colloidal silver uk aquasilver), wound dressings, medical devices and domestic products show a three stage sequence involving: Attachment of the silver cation (positively charged ion, i.e. Ag+) to exposed anionic (negatively charged ion) groups on the cell membrane or enzymes with a special role in maintaining cell wall structure. Denaturation  of the cell membrane, which leads to loss of structural integrity and functional capacity. Also leakage of essential nutrients, electrolytes and metabolites. Internalisation of silver by the bacterium or fungus. The silver binds to proteins and inhibits enzyme synthesis and respiratory activity. Also impaired DNA/RNA synthesis .
Hospital-acquired infection (HAI) — also known as nosocomial infection — is an infection that is contracted from the environment or staff of a healthcare facility. It can be spread in the hospital environment, nursing home environment, rehabilitation facility, clinic,or other clinical settings. Infection is spread to the susceptible patient in the clinical setting by a number of means. Health care staff can spread infection, in addition to contaminated equipment, bed linens, or air droplets. The infection can originate from the outside environment, another infected patient, staff that may be infected, or in some cases, the source of the infection cannot be determined. In some cases the microorganism originates from the patient's own skin microbiota, becoming opportunistic after surgery or other procedures that compromise the protective skin barrier. Though the patient may have contracted the infection from their own skin, the infection is still considered nosocomial since it develops in the health care setting .
The important part of an enzyme is called the active site. This is where specific molecules bind to the enzyme and the reaction occurs. Anything that changes the shape of the active site stops the enzyme from working. This is similar to a key that opens a door lock. It does not matter what a key handle looks like, but if you change the shape of the ‘teeth’ the key no longer works. The shape of the active site is affected by pH. This is why enzymes will only work at a specific pH, as well as a specific temperature. Change the pH and the enzyme stops working. Increasing the temperature to 60°C will cause a permanent change to the shape of the active site. This is why enzymes stop working when they are heated. We say they have become denatured .
3. Alan B.G. Lansdown, Silver in Healthcare, Its Antimicrobial Efficacy and Safety in Use. RSC Publishing, 2010