Multi-resistant microbes are a growing danger. In just three hours, a new rapid test would give information on which available antibiotic is still effective in a concrete case.Faster diagnostics allow a personalized therapy and saves lives.

Scientists of the Leibniz-Institute of Photonic Technologies (Leibniz-IPHT), Center for Sepsis Control and Care at the University Hospital Jena and Friedrich Schiller University work at a faster and cheaper alternative for hitherto time-consuming pathogen diagnostics.

Project manager Prof. Ute Neugebauer illustrates the advantages of this new approach: "We combine light-based analytical methods with microfluidic sample processing. With our Lab-on-a-Chip system, thus a miniaturized lab, we can clearly identify bacterial strains and their resistance, in less than three hours".

Standard practices for the infectious diagnostics require up to 72 hours to allow for a reliable result. This is because the number of pathogens in a patients sample is too small to conduct tests.

The analysis is therefore only possible after time-consuming cultivation. Especially in the clinical application during treatments of severe infections, e.g., sepsis time is a crucial factor. Intensive physicians are confronted with an alarming dilemma.

"Far too often we have to administer broad-spectrum antibiotics 'blindly' because we can neither analyze pathogen nor potential resistances. Therefore, we possibly use a sled-hammer to crack a nut. A vicious cycle that aides the development of new resistances", explains Michael Bauer, director of the Clinic of Anesthesiology and Intensive Care at the University Hospital Jena.

The new method out of Jena provides the much faster diagnosis as the basis for a decision of a reliable therapy. Ute Neugebauer, who works at Leibniz-IPHT and the University Hospital Jena points to tiny electrodes that are fixed on the surface of a stamp-sized chip: "Electric fields secure bacteria in a very small area."

Jena's scientists then applied various antibiotics in different concentrations on the trapped bacteria and examined them with Raman spectroscopy. "This means that we irradiate the pathogens with laser light and evaluate the scattered light spectrum," describes Neugebauer.

Jürgen Popp, director of the Leibniz-IPHT, explains: "After two hours we could detect distinct changes in the Raman spectra. We also got information on the needed concentration of the antibiotic to constrain bacterial growth. This is an important diagnostic parameter that influences the success of a treatment decidedly."

The combination of fast, light-based diagnostics and a high automation level reduces the time from sampling to result from 72 to three and a half hours. "Such a fast procedure could revolutionize diagnostics of infectious diseases," Prof. Bettina Löffler, director of the Institute of Medical Microbiology at the University Hospital Jena, is sure about that.

Currently, researchers work at a platform for the application in hospitals. Another, more far-reaching, the aim is the further development of a cartridge-based rapid test system, which will enable general practitioners to identify resistances in a fast and easy way for the first time.