Gold-based drugs could hold secret to treating superbugs, study finds

Gold-based drugs could hold the key to treating superbugs, researchers have found.

Scientists in Spain have identified 19 compounds that are effective against at least one antibiotic-resistant bacterium — and some of the drugs work against several strains.

Antibiotics are used to treat bacterial infections but, each time someone takes them, the chance of developing resistant bacterial strains known as superbugs rises.

Sometimes that happens because of antibiotic overuse, which happens when they are prescribed, but not necessary, for example for flu, which is caused by a virus.

But experts say superbugs can also develop when patients stop an antibiotic course midway through treatment, causing only the weakest cells to die as the stronger, more resistant bacteria multiply and mutate.

Drug-resistant infections kill about 700,000 people a year globally — a figure projected to rise to 10 million by 2050 if no action is taken.

And the development of new antibiotics has stalled, making antibiotic resistance one of the greatest public health threats facing humanity.

But gold metalloantibiotics — compounds with a gold ion at their core — offer a promising new approach due to their antibacterial properties.

To find out more, Dr Sara M. Soto Gonzalez, of the Barcelona Institute for Global Health, Barcelona, Spain, and colleagues studied the activity of 19 gold complexes against a range of multidrug-resistant bacteria isolated from patients.

She said: “All of the gold compounds were effective against at least one of the bacterial species studied and some displayed potent activity against several multidrug-resistant bacteria.

“It is particularly exciting to see that some of the gold complexes were effective against MRSA and multidrug-resistant A. baumannii, as there are two biggest causes of hospital-acquired infections.”

The research, which is being presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Copenhagen, focused on six bacteria, which lead to conditions such as pneumonia, blood and urinary tract infections.

All of the strains studied were multidrug-resistant. Four of them — S. aureus, P. aeruginosa, A. baumannii and E. coli are on the World Health Organisation’s list of antibiotic-resistant ‘priority pathogens’.

Another strain, multidrug-resistant S. maltophilia is increasingly being found in the lungs of people with cystic fibrosis.

In tests, 16 out of 19, or 84 per cent, of the gold complexes were highly effective against MRSA and S. epidermis.

Another 16 of the complexes were effective against the other bacteria, all of which are “gram negative”, which means they have a greater inbuilt resistance to antibiotics and the need for new treatments is particularly pressing.

Gold complexes use a variety of techniques to kill bacteria, including by stopping enzymes from working, disrupting the function of the bacterial membrane and damaging the bacteria’s DNA. This process should prevent antimicrobial resistance from developing, said the scientists.

Dr Gonzalez said: “The type of gold complexes we studied, known as gold (III) complexes, are relatively straightforward and inexpensive to make. They can also be easily modified and so provide a vast amount of scope for drug development.

“With research on other types of gold metalloantibiotics also providing promising results, the future is bright for gold-based antibiotics.”