Scientists say they have engineered a new antibiotic that appears promising in early clinical trials against kidney infections and urinary tract infection (UTI).

The new antibiotic, cefiderocol, acts like the "trojan horse" in Greek legend to trick bacteria into allowing it to enter, the BBC reported on Friday.

Trials on 448 people, reported in the Lancet Infectious Diseases journal, with a kidney or UTI suggested the drug was as effective as current treatments.

"This important study offers hope for a new antibiotic that could potentially be an alternative to treating them, but we are not there yet," Serge Mostowy, Professor from the London School of Hygiene and Tropical Medicine, was quoted as saying. 

The drug takes inspiration from the story of the giant wooden horse which was used to sneak Greek warriors into the city of Troy.

But instead of wood, iron is used to smuggle an antibiotic into bacteria.

"During an acute infection, one of our innate immune responses is to create an iron-poor environment," said Simon Portsmouth, from Shionogi Inc, a Japanese pharmaceutical company, who developed the drug.

"In response, bacteria increase their iron intake," he added.

Cefiderocol binds to iron and, in a deadly mistake, bacteria transport it past their defences and inside their cells.

"Cefiderocol was found to be both safe and tolerable," Portsmouth said.

Bacteria becoming resistant to antibiotics is making some infections incredibly difficult to treat.

The Review on Antimicrobial Resistance made stark predictions for the future, including 10 million people dying every year from drug-resistant infections by 2050.

Yet new drugs are in scarce supply, the report said.

Experiments on people with pneumonia and those with infections that are resistant to some of our most powerful drugs, carbapenems, are already under way.

However, much larger trials are needed to be sure of the effectiveness of the cefiderocol that attacks bacteria in a completely new way, the researchers said.