Researchers found that taking antibiotics with sugar could dramatically improve their effectiveness against stubborn infections such as tuberculosis.

Laboratory tests showed that glucose and fructose - a type of sugar found in plants - stimulated bugs and made them more vulnerable to drug treatments.

Professor James Collins, from Boston University, said: "You know the old saying: 'a spoonful of sugar makes the medicine go down? This is more like 'a spoonful of sugar makes the medicine work'."

Chronic and recurrent infections often occur when bacteria shut down and become metabolically dormant.

This allows the bugs, known as "persisters", to dodge the effects of antibiotics.

Over the course of weeks or months, the bacteria return to life, often stronger and more aggressive than they were before, and the patient relapses.

Persistent bugs are different from those that develop antibiotic resistance through genetic mutations, but may be just as much of a problem.

Bacterial resistance can stretch illnesses out over months and cause infections to spread to kidneys and other organs.

The scientists looked at a new way of tackling persistent bacteria by rousing them from hibernation using a simple weapon, sugar.

They found that sugar acts as a stimulant that switches on normal bacterial responses, rendering the bugs vulnerable to antibiotic attack.

Testing the strategy on Eschericia coli (E. coli) bacteria, a common cause of urinary infections, the researchers were able to eliminate 99.9 per cent of persisters within just two hours.

Without sugar, the drugs they used had no effect.

The approach, reported in the journal Nature, was similarly effective against persistent Staphylococcus aureus bacteria, which can produce serious infections.

Prof Collins now plans to investigate whether sugar additives can improve the effectiveness of drugs against tuberculosis (TB).

TB is a chronic lung infection responsible for more deaths worldwide than any other infectious disease.

Each day around 4,700 people die from the effects of TB, according to the World Health Organisation.

"Our goal was to improve the effectiveness of existing antibiotics, rather than invent new ones, which can be a long and costly process," said Prof Collins' Boston University colleague, Kyle Allison, who was the first author on the study.

The findings have the potential to improve the lives of untold numbers of people who struggle with nagging infections, while also reducing healthcare costs substantially, he added.