How Researchers Use Localized Surface Plasmons to ­Decode the Genetic Signatures of Bacteria and Uncover Antibiotic Resistance

The increasing spread of antibiotic resistance poses a global threat to human health, rendering our most important weapons against bacterial infections ineffective and making it more difficult to treat otherwise curable diseases. A research team at Leibniz IPHT has developed a new sensor based on localized surface plasmon resonance (LSPR) to monitor the spread of antibiotic resistance. This cheap and simple method allows the identification of genes that make bacteria immune to common antibiotics.

Researchers use light and nanoparticles to decode the genetic signatures of specific bacteria. Anne-Kathrin Dietel, Florian ­Seier and Stephan Kastner from the Department of Nanobiophotonics exploit the special optical properties of tiny metal structures called nanoparticles. These nanoparticles interact with light in a special way known as localized surface plasmon resonance. In this phenomenon, the free electrons of the nanoparticles oscillate in unison with the incident light waves, creating a clearly visible color resonance.

Customized Nanoparticles

The researchers are developing metal nanoparticles with precisely defined optical properties. They combine these customized particles with biomolecules, such as DNA, to create functional nanostructures. Using this approach, they have developed an optical sensor that can detect bacterial resistance genes with a high degree of accuracy. In particular, they focused on the blaSHV gene, which makes bacteria resistant to a broad spectrum of antibiotics.

The blaSHV Gene: A Carrier of Resistance

“This antibiotic resistance gene can render beta-lactam antibiotics, one of the most commonly used classes of antibiotics, ineffective,” explains Anne-Kathrin Dietel. “The fact that these genes are transmitted by horizontal gene transfer between different bacterial species significantly accelerates the spread of antibiotic resistance.”

“A key advantage of our method is that it does not require the usual markers or dyes and can be extremely miniaturized,” explains Stephan Kastner. “This aspect makes the test simpler, faster and cheaper.” The researchers demonstrated the efficiency of the sensor by detecting even single point mutations of the blaSHV gene, which are crucial for selecting the appropriate resistance gene inhibitor during treatment.

The research results could facilitate the selection of the right treatment for infections in clinical diagnostics and improve the monitoring of the spread of antibiotic resistance.

Original publication: https://doi.org/10.1002/smll.202207953