Rapid Test for Antibiotic Resistances in Urological Sample Material by Surface Enhanced Raman Scattering SERS

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In the framework of the project, a combination of surface-enhanced Raman scattering (SERS) with a particular in-situ synthesis method for the SERS-active colloids will be investigated and applied as rapid antibiotic resistance tests. Preliminary studies demonstrate that the specific approach is suitable to reveal within few minutes the efficiency of antibiotics against specific microorganisms on a single organism basis as well as in suspension. As opposed to current approaches, our new method identifies the antibiotic effect of different substances not based on minute changes of the Raman spectrum, but on its effect upon generation and aggregation of the SERS-active colloids. The depolarization of the transmembrane potential by the antimicrobial substance apparently prevents in situ synthesis on the particles´ surface, or the aggregation of the particles there. In consequence, no SERS enhancement takes place and thus, no significant SERS-signal of a dead organism can be detected. This leads to a high significance of the distinction of living and dead organisms, with highly structured and specific signals of the living organisms and essentially a baseline signal for dead organisms. The approach was successfully tested for several E. coli strains. In less than one hour, Polymyxin B-resistant strains could be distinguished from non-resistant strains, with the first significant results available in less than 10 min. The aim of the project is a concise test and validation of the novel approach with respect to applications in urology. Suitable sample preparation as well as data evaluation strategies will be developed, a key focus being set on the compromise between statistical reliability and short analysis time of one to two hours.