4.2 Metals

In the fourth century BCE, the Greek physician Hippocrates used metals such as copper and silver to treat wounds (Alexander, 2009). Thus metals could be the oldest antimicrobial agents. More recently, dressings impregnated with silver have been used to improve wound healing. However, we are only just starting to understand how these metals exert these effects.

Metals can:

• disrupt biofilms
• act togther with other antibacterial agents
• inhibit bacterial metabolism
• kill bacteria.

The mechanisms that metals use to kill bacteria depend on the chemistry of the metal but they can include:

• producing chemicals that damage DNA
• damaging bacterial proteins
• disrupting the bacterial cell membrane
• preventing bacteria from acquiring the nutrients they need to grow.

It is important to remember that metals can also be toxic to humans, which may limit their effectiveness as antibiotic alternatives.