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Zinc at the frontline in fighting superbugs

02 Dec 2013

Researchers have discovered that zinc is much more than an eponymous cream smeared on lips and noses to protect against the sun.

Scientists from the University of Queensland and the University of Adelaide have found that it is an effective shield against one of the world’s most deadly bacterial infections.

The researchers discovered that zinc blocks a protein transporter in Streptococcus Pneumoniae, preventing it from accessing manganese, which the bacteria requires to invade and cause disease.

Streptococcus Pneumoniae can cause pneumonia, meningitis and other infectious diseases, and is responsible for more than one million deaths a year. It particularly affects infants, the elderly and people with compromised immune systems.

The finding is particularly significant because antibiotic-resistant strains of Streptococcus Pneumoniae emerged more than 30 years ago, and up to 30 per cent of such bacterial infections are now considered multi-drug resistant.

The researchers found that the protein transporter in Streptococcus Pneumoniae binds with manganese and zinc differently, because of the difference in size between the two metals. When the protein binds with zinc it closes too tightly around it, because of zinc’s smaller size, causing an essential spring in the protein to unwind too far, jamming shut and blocking the transporter from binding with manganese.

Lead researcher Dr Christopher McDevitt, from the University of Adelaide, said the finding opens the way for further work to design antibacterial agents to fight the bacteria.

“It has long been known that zinc plays an important role in the body’s ability to protect against bacterial infection, but this is the first time anyone has been able to show how zinc actually blocks an essential pathway, causing bacteria to starve, “Dr McDevitt said.

“Without manganese, these bacteria can easily be cleared by the immune system.

“For the first time, we understand how these types of transporters function. With this new information, we can start to design the next generation of antibacterial agents to target and block these essential transporters.”

The research was published in Nature Chemical Biology.

Kirsty Waterford

Published: 02 Dec 2013