Researchers from Leibniz-IPHT in Jena explain in the podcast “Mikroben im Visier” how Raman spectroscopy can detect resistant bacteria within a few hours. In the future, this method could help identify effective antibiotics more quickly and reduce the use of broad-spectrum antibiotics.

In cases of severe infections, every hour counts. Doctors often have to decide quickly which antibiotic to use. However, traditional resistance tests using bacterial cultures often take one to several days to determine which antibiotic is effective against the specific pathogen. During this time, patients are often given broad-spectrum antibiotics designed to target as many pathogens as possible. While this can save lives, it also contributes to the development of antimicrobial resistance.

The new episode of the podcast of the Leibniz Research Alliance INFECTIONS Mikroben im Visier explores how laser-based diagnostics could speed up resistance testing. Dr. Anja Silge and Marie-Luise Enghardt from the Leibniz Institute for Photonic Technologies (Leibniz-IPHT) explain how Raman spectroscopy can detect resistant bacteria within a few hours. In the future, this method could help identify effective antibiotics more quickly and reduce the use of broad-spectrum antibiotics. In conversation with Dr. Elisabeth Pfrommer and Dr. Christian Nehls, the two scientists describe the fundamentals of Raman spectroscopy. The method is based on a physical effect described by the Indian physicist and Nobel laureate C. V. Raman as early as the beginning of the 20th century. When a sample is irradiated with laser light, a small portion of the scattered light changes its energy. The changes in the scattered light produce a characteristic spectrum that allows conclusions to be drawn about the molecular composition of the sample.

Today, this method is also used for biological samples, such as pathogens like Escherichia coli, Staphylococcus aureus, or Klebsiella pneumoniae. Each bacterium leaves behind a characteristic “light fingerprint.” In the podcast, the researchers explain how the technology can be used to detect antibiotic resistance. “The spectral pattern of a resistant bacterium during antibiotic treatment differs from that of a sensitive one. This allows us to quickly determine whether the antibiotic is effective or not,” says Anja Silge.

To do this, the bacteria are first incubated with antibiotics for about 90 minutes and then analyzed using the laser. Including evaluation, the entire test takes about three hours. The method already achieves over 90 percent agreement with clinically established resistance tests.

“Thanks to the shorter diagnostic time, it is possible to use antibiotics in a highly targeted manner—specifically those that are effective against the pathogen in each case, says Dr. Anja Silge. This could reduce the unnecessary use of broad-spectrum antibiotics and curb the emergence of resistant pathogens. The technology is making visible progress toward practical application. The research team is currently working with compact Raman devices and special chips that require only very small amounts of sample material. The goal is to achieve robust and standardized results. “We are already measuring real patient samples in the clinic,” reports Marie-Luise Enghardt.

To enable broad clinical application, the studies are now set to be expanded and the technology transferred to small-scale production.