The antibiotic, named teixobactin, has been shown to kill infections in mice without encountering any detectable resistance.
Researchers say it may be six years before the antibiotic is approved for human use, but believe it marks a breakthrough in the fight against bacterial disease.
Teixobactin has been shown to fight resistant strains of tuberculosis and Staphylococcus during laboratory experiments.
The drug works by binding to fatty molecules that are the building blocks for bacterial cell walls.
The binding point is less prone to mutation – the evolutionary process that drives drug resistance.
Kim Lewis, a professor at Northeastern University in the US and co-founder of NovoBiotic Pharmaceuticals, which has patented teixobactin, says the discovery is promising.
“The discovery of this novel compound challenges long-held scientific beliefs and holds great promise for treating an array of menacing infections,” he said.
There has been a spike in the detection of drug-resistant superbugs over recent years.
The World Health Organisation warned last year of a post-antibiotic era, where basic healthcare becomes dangerous due to the risk of infection during operations.
Scientists have welcomed the finding, but cautioned that human trials of teixobactin would be key to its future success.
“The discovery of a potential new class of antibiotics is good news,” said Richard Seabrook of Britain’s Wellcome Trust medical charity.
“Screening previously unculturable soil bacteria is a new twist in the search … and it is encouraging to see this approach yielding results.
“However, we will not know whether teixobactin will be effective in humans until this research is taken … to clinical trials.”