Laser-based method to detect antibiotic resistant bacteria invented by UK scientists

Researchers have developed a new, quicker way of detecting drug resistance in bacteria, taking about 45 minutes, an advance that may help clinicians prescribe antibiotics correctly and reduce their misuse.According to the researchers, including those from the University of Sheffield in the UK, the standard method for detecting antibiotic resistance in bacterial samples is a relatively slow process that typically takes between 12 and 24 hours. They said the new technique, described in the journal ACS Sensors, uses nanotechnology to detect resistance in approximately 45 minutes, and can help in the ongoing battle against drug-resistant bacteria – a problem which is predicted to cause 10 million deaths per year and cost the global economy USD 100 trillion by 2050. The scientists believe speeding up the time it takes to identify antibiotic-resistant bacteria could improve the ability of clinicians to prescribe antibiotics correctly and reduce their misuse – a key step in the fight against drug resistance. They said the new method uses a nano mechanical sensor and a laser to detect single bacterial cells as they pass through the light’s focus, providing a simple readout of antibiotic resistance by detecting growth (resistant) or death (sensitive) of the bacteria. By placing a reflective surface – a small stiff cantilever – in a filtered growth medium in a petri dish, and reflecting a laser off it onto a detector, the researchers said it is possible to detect bacteria as they pass through the path of the laser, therefore altering the signal at the detector. Following the addition of the antibiotic to the petri dish, the study showed that it is possible to detect whether fewer bacteria interfere with the laser beam – indicating cell death in the antibiotic-sensitive bacteria. “Our method allowed us to quickly differentiate between resistant and sensitive phenotypes in multiple strains of E. coli, a bacterium implicated in a number of challenging infections including UTIs,” said Isabel Bennett, a co-author of the study from the University College London in the UK. “We were able to show that our faster method was able to reproduce values from gold standard measurements, such as MIC’s in a fraction of the time,” said Alice Pyne, another co-author of the study from the University of Sheffield.