Bacteria killed with silver can turn into “zombies” that kill living microbes, scientists have discovered.
In the study, strains of Pseudomonas aeruginosa were killed with silver nitrate solution, a common antibacterial agent. The dead bacteria were then exposed to living strains of the same type.
Silver is an ancient antimicrobial treatment, recognised as such since at least 400 BC. It works by punching holes in the membranes of bacteria and binding to essential cell components.
And the new study suggests it “can kill generation after generation”.
“If an antibacterial agent remains chemically active after the killing action, then this is not the end of the story, but only the beginning of it”, says the study’s lead author Dr David Avnir of the Hebrew University of Jerusalem, in Israel.
“In principle, if not washed away, the same amount of agent can kill generation after generation,” says Avnir.
The study, published in the journal Scientific Reports, is the first to report this antibacterial mechanism.
“The new mechanism offers an explanation to the observation that in many cases the activity of antibacterial agents is prolonged, much beyond what one would expect from the administered dose,” Avnir says.
Bill Condie is a science journalist based in Adelaide, Australia.
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