TB Bacteria Measured with Light and Sound

A U.K.-wide research team, led by the School of Physics and Astronomy and the School of Medicine at the University of St Andrews, has developed an innovative way to monitor the reaction of living bacteria to antibiotics by using lasers and sound. The study, in collaboration with the University of Southampton, opens the door to studying the response of any microorganism to various antivirals and antibiotics.

This new approach could lead to a more detailed understanding of antimicrobial resistance and shortening the treatment for the world’s leading infectious disease, tuberculosis (TB), which causes about a million deaths every year.

Bacteria can be grown in the laboratory and tested on new antibiotics, but these methods are limited. Ideally, researchers want to isolate bacteria from external influences and observe their response in a noninvasive way. To address this, the St Andrews-led team developed a new device that harnesses the powers of both light and sound.

The team used sound waves to levitate and immobilize living bacteria in a small chamber. Then by scattering light from the bacteria, they recorded a Raman signal, an optical fingerprint that reveals the molecular composition of the bacteria. This combination of sound and light allowed the team, for the first time, to measure real-time changes of the bacteria due to existing antibiotics used for TB.

“This is a first study to tackle the problem of studying infectious disease with lasers and sound,” said Mingzhou Chen, a senior research fellow from the Optical Manipulation Group at the School of Physics and Astronomy. “We hope researchers will be able to use this innovative way to look at living bacteria and beyond.”

“This new tool will help us to understand why TB treatment takes so long and could be a platform for testing new drugs,” said Stephen Gillespie, leader of the infection group at the University of St Andrews School of Medicine.

The research was published in Nature (www.doi.org/10.1038/s42003-020-0915-3).