Overcoming resistance to antibiotics

12 October 2017

Microbiologists from University of Hong Kong have discovered a chemical compound that could treat a deadly superbug without using antibiotics.

This is believed to be the first time that chemical genetics is used to tackle the superbug Methicillin-resistant Staphylococcus aureus, a breakthrough offering hope for the global fight against drug-resistant bacteria.

Professor Yuen Kwok-yung (Croucher Senior Medical Research Fellowship 2006) who proposed the study, said the study involving methicillin-resistant Staphylococcus aureus (MRSA) could help tackle a problem the World Health Organisation considers an “increasingly serious threat to global public health”.

MRSA is one of the world’s most threatening superbugs. It is a strain of the Staphylococcus aureus bacteria that is resistant to antibiotics, including methicillin, oxacillin, penicillin, amoxicillin and cephalosporins. Improper use of antibiotics has contributed to the rise of the usually fatal superbug infections.

MRSA usually causes skin and soft tissue infections such as boils, abscesses or wound infections. The infected area may produce pus and sometimes leads to serious conditions such as bloodstream infections, lung infections and necrotizing fasciitis. Patients who have been hospitalized after surgeries are most susceptible to the infection.

Yuen said around 45 per cent of all Staphylococcus aureus cases in Hong Kong were methicillin-resistant, or MRSA cases – four times higher than the percentage in Britain. In the first seven months this year, the Centre for Health Protection recorded 739 cases of community-associated MRSA infection who were aged 15 days to 100 years old.

The breakthrough came when the researchers enlisted a different approach from the conventional method of using antibiotics to kill bacteria, which has led to the growth of superbugs.

“If we don’t have to kill the bacteria but still inhibit its growth, we could solve the problem of antimicrobial resistance,” Yuen explained.

In the latest study, the HKU scientists identified a chemical compound named NP16 that inhibited a substance produced by MRSA called staphyloxanthin, which can resist the body’s immune system.

“NP16 could stop MRSA in producing defensive shields ... now we have disarmed MRSA and allowed our body to kill the bacteria more easily,” lead researcher Dr Richard Kao Yi-tsun said. “It would also be very difficult for the bacteria to cause infection.”

In experiments involving the cells and organs of infected mice, bacteria levels fell by a factor of 10 in a few days’ time with the help of NP16. The chemical compound was also revealed to be non-toxic to human cells. “Once we killed the bacteria, there were always survivors that became drug-resistant,” Kao recalled. “Antibiotics use then became useless.”

The research team’s findings have been published in the scientific journal mBio, and the study received a top prize at a recent international conference. The team claimed the study was the world’s first to use chemical genetics to tackle MRSA infection.

The team had started to look into using the same approach to tackle other superbugs, including drug-resistant forms of E coli. They had been in touch with a local drug maker and the government to explore opportunities to develop NP16 into a drug. It is expected to take around three years to conduct pre-clinical research before the drug could be tested on patients in clinical trials.

To know more about the research, please click here