April 7 (UPI) -- For years, scientists have searched for a silver bullet to treat multidrug-resistant superbugs. Now, they may have found the solution in another precious metal: gold.
Several gold-based compounds have shown efficacy against hard-to-treat bacteria, according to new research to be presented at the European Congress of Clinical Microbiology and Infectious Diseases in Copenhagen, Denmark next week.
In a paper prepared for the conference, researchers said they found that gold-based antibiotics showed "great potential," especially against diseases that have proven resistant to other drugs.
Sara Soto Gonzalez, of the Barcelona Institute for Global Health in Barcelona, Spain, and fellow researchers studied the activity of 19 gold compounds against a range of multidrug-resistant bacteria isolated from patients.
Those bacteria studied included Methicillin-resistant Staphylococcus aureus, or MRSA; Staphylococcus epidermidis; pseudomonas aeruginosa; stenotrophomonasmaltophilia; acinetobacter baumannii; and pneumonia.
Scientists found that 16 of the 19 gold compounds were highly effective against MRSA and S. epidermis, and 16 were effective against the other bacteria, all of which are gram-negative. Researchers said that "gram negative" bacteria have a greater resistance to antibiotics, and they need new treatments.
Overall, all 19 compounds tested were effective against at least one of the hard-to-treat bacterium and some were effective against several.
"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," Soto 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."
Drug-resistant infections kill roughly 700,000 people annually around the world. The World Health Organization classifies antibiotic resistance as one of the greatest public health threats facing humanity.
The Centers for Disease Control and Prevent said that such antimicrobial resistance happens when germs like bacteria and fungi develop the ability to defeat the drugs designed to kill them, making them almost impossible to treat.
Gold is known to have antibacterial properties, making gold metalloantibiotics -- compounds with a gold ion at their core -- one of the most promising new approaches.
"Gold complexes use a variety of techniques to kill bacteria," Soto Gonzalez said. "They stop enzymes from working, disrupt the function of the bacterial membrane and damage DNA.
"With research on other types of gold metalloantibiotics also providing promising results, the future is bright for gold-based antibiotics."