Acinetobacter baumannii was once treatable with normal antibiotics but is now one of the most worrying superbugs threatening the medical system. It has been particularly associated with infections of military personnel injured in Iraq and Afghanistan. (Credit: A.J. Cann/Flickr)

antibiotics

This scary superbug has a weak spot

Scientists have pinpointed a potential way to stop a hospital superbug that causes deadly infections and is very resistant to antibiotics.

The infections are common among soldiers treated in medical facilities in Iraq and Afghanistan.

The pathogen, known as Acinetobacter baumannii, has a resistance protein that allows bacteria to survive chlorhexidine, an antiseptic commonly used in wipes, cleansers, and mouthwashes in hospitals.

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Researchers at the University of Leeds and Macquarie University in Australia showed how the superbug can pump the antiseptic out of its system.

The findings are critical for the design of new chemicals to combat the germ.

“The Australians saw that, in response to chlorhexidine, a gene becomes active and produces a protein they called Acinetobacter Chlorhexidine Efflux, or ‘Ace’ for short. Working together, we demonstrated that Ace binds to the antiseptic and effectively pumps the chlorhexidine that has leaked through the cell wall out again,” says Professor Peter Henderson of the University of Leeds’ School of Biomedical Sciences.

‘Catastrophic threat’

Acinetobacter baumannii was once treatable with normal antibiotics but is now one of the most worrying superbugs threatening the medical system. It has been particularly associated with infections of military personnel injured in Iraq and Afghanistan.

Its ability to survive on disinfected artificial surfaces for long periods has allowed it to thrive and spread through the military and into the civilian medical system.

Sally Davies, the Chief Medical Officer for England, said in March that antibiotic resistance posed a “catastrophic threat” that could mean that even minor surgeries might carry deadly risks by the 2030s.

Henderson says identifying the resistance protein “now allows us to look for a compound that will inhibit the protein’s activity and form the basis of a new treatment against infection.”

The early indications are that the protein specifically binds with chlorhexidine rather than other antibiotic molecules. Although some multi-drug resistant proteins have been found, the fight against superbugs has generally been characterized by a painstaking search for several proteins associated with resistance to particular drugs and chemicals.

“There are very similar genes in other pathogenic organisms,” says Henderson. “Our next step will be to explore what these proteins do in those other organisms. In some cases, it is strongly suggested that they make the germ resistant to chlorhexidine, but in others it appears to be something else. We need to find out what that is.

“The bad news is that the bugs are winning. We can’t devise new antibiotics nearly fast enough to find a new way of dealing with them and there is not enough funding to pursue the research.”

Professor Ian Paulsen at Macquarie University says antiseptics and disinfectants are “a key defense used to control the spread of these bacteria in hospitals particularly. Following this discovery, we plan to investigate ways to block this pump. Such work is important in ensuring that we can continue to use successfully this antiseptic to reduce rates of infection in hospitals.”

The research is published in the Proceedings of the National Academy of Sciences. The work was funded under a European International Research Staff Exchange Scheme (IRSES) project involving the University of Oslo, University of Leeds and Macquarie University. Researchers from Flinders University, Australia, also contributed to the research.

Source: University of Leeds

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