Rapid antibiotic resistance testing in urological samples via surface enhanced Raman scattering

Objectives

Urinary tract infection (UTI) is one of the most frequently occurring bacterial infections worldwide and thus represents a heavy burden on the healthcare system. It is often caused or accompanied by evolution of bacteria that show high resistance towards a wide range of antibiotics. Hence, fast antibiotic susceptibility tests are vital.

The aim of the project is to fully investigate the feasibility of a SERS-based assay on with real samples, a range of clinically relevant bacteria species and strains, as well as antibiotics. The influence of the biological matrix is investigated and suitable sample preparation methods will be developed in order to allow for successful use independent on the chemical environment of the sample.

We are also working on a sampling platform for the handling of the sample, which is suitable for the sample pre-treatment as well as for the Raman-microscopic investigation. The test conditions will be elaborated in close collaboration with the project partners, which guarantees a sustainable work procedure. Finally, the capacity of the method shall be tested in comparison with routine analysis and thus the applicability of the method can be evaluated.

Experimental setup and analysis scheme for the antibiotic susceptibility testing by SERS using an in situ synthesis of bacteria@AgNPs as viability test.

Method of Approach

SEM pictures of pure E. coli K12 (top) and E.coli K12@AgNP (bottom).

Raman microscopy allows the characterization of aqueous samples, it finds more and more applications microbiological samples.

Recently, we presented a SERS-based method to distinguish living and dead bacteria, using an in situ formation of silver nanoparticles on the bacteria cell wall. This approach promises to be suitable for a fast testing of bacteria within the time of a few minutes. Furthermore, the use of Raman as microscopical method allows single cell measurement and thus would even make cultivation obsolete.

Typical mean SERS spectra of bacteria composed of single measurements.

Financial Support

DFG

Responsible

Christoph Haisch
PhD Student David Bauer

Partners

Prof. Dr. med. Christian Stief, Urologische Klinik der LMU München
PD Dr. Andreas Wieser, Max von Pettenkofer-Institut, LMU München