Marie-Luise Enghardt (Jena / DE), Richard Grohs (Jena / DE), Anja Silge (Jena / DE), Uwe Glaser (Jena / DE), Oleg Ryabchykov (Jena / DE), Franziska Hornung (Jena / DE), Stefanie Deinhardt-Emmer (Jena / DE), Bettina Löffler (Jena / DE), Jürgen Popp (Jena / DE)
Introduction
Antibiotic resistance has become a major public health concern, complicating infectious disease treatment and has severe medical and financial implications. To overcome these problems, there is an urgent need for faster antibiotic susceptibility testing. One approach is to use Raman spectroscopy to rapidly investigate the phenotypic response of pathogens to antibiotic treatment.
Goals
The RamanBioAssay™ (RBA) platform [Kirchhoff et. al. 2018] will be employed as a rapid antimicrobial susceptibility test (AST) for clinical isolates of Escherichia coli and Staphylococcus aureus strains. The information from the Raman data obtained from both resistant and sensitive strains will be matched with the findings from microdilution tests. The results will focus on the interpretation and extrapolation of Raman-based AST results to enable reliable and growth-independent analysis for potential diagnostic use.
Methods
E. coli and S. aureus strains are exposed to appropriate antibiotic concentrations of respectively Ciprofloxacin and Oxacillin as part of the RBA. In a dielectrophoresis-chip, bacteria are collected in a micrometre range for high-quality Raman measurements directly from bacterial suspensions. The readout of phenotypic molecular changes during antibiotic treatment is possible after only 90 min of bacteria-antibiotic interaction, ensuring the entire test is completed in ≤ 3 hours. Finaly, chemometrics translates spectral signals into antibiograms.
Results
A successful measurement of clinical samples within the RBA is possible. The interaction time of only 90 min between bacteria and antibiotics is enough to detect the antibiotic effects by Raman spectroscopy. The results are consistent with those of the gold standard and current routine diagnostics.
Summary
Common bacteria for bloodstream infections, E. coli and S. aureus, were successfully treated with appropriate antibiotic concentrations and tested using on-chip Raman spectroscopy. The method enables precise detection of phenotypic susceptibility to antimicrobial agents. The test therefore represents an improvement over both the gold standard and current routine diagnostics.