New MRSA antibiotic may in future replace obsolete drugs

Maynooth University researchers are developing a promising new kind of antibiotic that readily kills off the main hospital superbug, MRSA.

It may provide the basis for an entirely new class of antibiotic that could substitute for others that are no longer effective.

The starting point for the research is a chemical based on quinine. Extra chemical components have been added to deliver a high level of antibacterial activity.

The find could have huge implications if a new class of drug does actually come from the research.

No new antibiotic form has been released since before the 1980s, and many bacteria have become resistant to the older antibiotics.

Hospital environments

Antibiotic-resistant organisms have flourished in hospital environments.

On any given day, one in 18 hospitalised patients are being treated for healthcare acquired infections, the researchers say, citing figures for Europe from the European Centre for Disease Prevention and Control.

MRSA and E coli are the key organisms involved, accounting for 64 per cent of cases.

The discovery is the result of three years of work. “We took a Lego-type strategy, looking at building blocks that might improve the medicinal chemistry,” said Dr John Stephens, a principal investigator at Maynooth’s Department of Chemistry.

He led the research with Maynooth's Dr Kevin Kavanagh at the Department of Biology, and Niamh Dolan, lead author of a research paper published online in the journal Bioorganic and Medicinal Chemistry Letters.

The team used quinoline thiourea as the starting point of their research. The molecule was known but was not used in medical chemistry, Dr Stephens said.

He works with catalysts, chemicals used to enhance chemical reactions, and also in the development of molecules that have medical properties.

Screening process

“We looked at catalysts and put them through a screening process which help identify those with antibiotic activity,” he said.

They came up with a number of versions and settled on one based on quinoline thiourea. “It has proven to be very effective based on its antibacterial properties,” Dr Stephens said.

"It is particularly good against Staphylococcus aureus, E coli and MRSA and is almost as good against them as Vancomysin."

Vancomysin is one of the “last line of defence” antibiotics which remain effective in treating drug-resistant bacterial infections.

Once discovered, the team made a number of versions of the drug and all of them worked against these bacteria.

They also tested the drug for toxicity by introducing it to the larvae of the greater wax moth.

They found 100 per cent survival at a range of concentrations and the drug did not damage normal development of the larvae.

‘A significant first step’

The research represented “a significant first step” on the way towards finding a new class of antibiotic, Dr Stephens said. He remains optimistic about the importance of their find, but also cautious.

“We are probably a few years from someone saying this is a new class of antibiotic. We need to know how it works and if related compounds will work,” he added.

“It will probably be the next generation of this compound that ends up on the shelf.”

The research group will now look for ways of improving the antibacterial properties of the chemical, he said.

Funding for the research came from the Higher Education Authority and the EU via its Regional Development Fund.