A man-made protein, which is similar to proteins used by white blood cells to punch holes in bacteria will be tested in clinical trials by Canadian researchers.
The small molecules developed by biochemists at the University of Pennsylvania in Philadelphia may provide a potential way to deal with antibiotic-resistant "superbugs", says a report.
The molecules called PMX-30063 are electrically attracted to the bacterium's outer membrane, and fuse with it to create gaping holes that destroy invaders, the report adds.
Biochemist Bill DeGrado revealed that his team stripped down the structure of natural defensins to just the essential membrane-busting components, and made a defensin small enough to go undetected and unscathed by the immune system.
Preliminary tests conducted by DeGrado's company Polymedix have shown that bacterial is less likely to develop resistance to the new defensin than antibiotics.
"For conventional antibiotics, you generally find it takes 100 times more of the antibiotic to kill the bacteria after 9 repeats. We've done 14 repeats with PMX-30063 and there is no change in its potency," New Scientist magazine quoted Nick Landekic, Polymedix's chief executive, as saying.
Michael Zasloff at Georgetown University, Washington DC, who was not involved with the work, said: "Their compounds are really exciting and look great, but the value of this class will be based on safety."
He pointed out that just as in bacterial cells, PMX-30063 might punch holes in human cells too.
"My concerns are with how it interacts with sites in the body known to be sensitive to damage by positively-charged peptides - areas such as the kidney and middle ear," he said.
DeGrado, however, said that the risk was low, and that the molecule was several thousand times more likely to target bacterial cells than it was to attack mammalian ones.
Impressed by a programme of animal testing, Canadian government's regulator Health Canada has given the go-ahead to human clinical trials.