The Reason For Silver Nitrate’s Prolonged Microbial Toxicity

In a newly discovered mechanism, after an antimicrobial silver agent kills bacteria, the agent is then capable of moving on to kill still more bacteria (Sci. Rep. 2015, DOI: 10.1038/srep09555). Dubbed the “zombies effect” by David Avnir of Hebrew University of Jerusalem and colleagues, the extended toxicity of silver nitrate stems both from the ability of the silver to form nanoparticles and remain active after it kills and from its subsequent release from the corpses of bacteria. The group first used silver nitrate to kill Pseudom­onas aeruginosa. They then separated and cleaned the dead bacteria and added them to a live culture of the same bacteria, killing more than 99.99% of them. Although the authors say it’s too early to make definitive predictions, they see this finding as being useful for wound-healing applications. Though the team studied only one death cycle, “one of our aims is to test how many generations of zombies can be extracted from a single dose,” Avnir says. “In principle, if the silver is not washed away, then many generations are expected.”