Color test ‘sniffs out’ dangerous staph strains fast

Researchers have developed a rapid colour-changing test that can distinguish between different strains of golden staph, including those likely to be virulent and antibiotic resistant. 

Golden staph is a major human pathogen and is a leading cause of infection-related deaths globally, with more than a million fatalities each year. 

The test uses tiny gold particles that behave like artificial enzymes (nanozymes) combined with short DNA molecular binders to create colour “fingerprints” unique to each strain. These fingerprints can help separate high-risk strains from others and inform next steps of care. 

The fingerprint test can also indicate whether a strain carries markers associated with increased virulence, and whether it is likely to have antibiotic resistance. 

Led by RMIT University, the research involved collaborators from the University of Massachusetts Amherst in the US, the National Institute of Pharmaceutical Education and Research in India and Western Sydney University.

Rapid and low-cost

Professor Rajesh Ramanathan said the team’s platform was a rapid, low-cost screening tool that could complement culture- and PCR-based tests. The test could be modified to spot different dangerous strains of other pathogens . 

“Speed matters when you’re dealing with serious bacterial infections, and today’s gold-standard tests take time, specialist infrastructure or both,” said Ramanathan, from the Sir Ian Potter NanoBioSensing Facility and NanoBiotechnology Research Laboratory within RMIT’s School of Science. 

“The rapid test gives clinicians an early, evidence-informed ‘heads-up’ if an infection may be more aggressive or harder to treat.” 

Subtle biological differences

Dr Pabudi Weerathunge from RMIT said the team deliberately built the system to capture subtle biological differences without needing prior knowledge of the bacteria’s surface. 

“Instead of hunting for one perfect target, we use a small panel of molecular binders that attach to different parts of the bacterial surface,” she said. 

“This is a practical pathway toward point-of-care style screening across clinical settings.” 

Tested in simulated wound conditions

To assess how the sensor might perform in more realistic environments, the team tested it in simulated wound fluid spiked with different golden staph strains. 
The sensor produced comparable strain fingerprints in simulated wound fluid and showed stronger and faster responses in some cases. 

Nano-biotechnology company Nexsen is partnering with the Sir Ian Potter NanoBioSensing Facility across clinical, veterinary and biosecurity diagnosis. 

“Working with a world class research team led by Distinguished Professor Vipul Bansal provides a translational edge,” Nexsen Managing Director Mark Muzzin said.

From the lab to clinical practice

Bansal, Founding Director of the Sir Ian Potter NanoBioSensing Facility, said working with industry was helping to move concepts from the lab into clinical practice.

“Our team continues to generate new sensing concepts, and working closely with industry means we can move faster toward real world impact.” 

‘Nanozyme aptasensor array for predictive sensing of virulent and antibiotic-resistant Staphylococcus aureus strains’ is published in the high-impact journal Small.

Other researchers on the study were Tarun Sharma, Wilson Wong, Mugdha Joglekar, Anandwardhan Hardikar, Mahdieh Yazdani and Vincent Rotello.

The work was supported by the Australian Research Council (ARC) Discovery scheme and ARC Industry Transformation Hub funding, and the Ian Potter Foundation-supported facility infrastructure at RMIT.