Research

Research Priorities

Optical, molecular and serological multiparameter analyses for clinical microbiological diagnostics and epidemiology
Focus: Detection and understanding of antibiotic resistance of pathogenic bacteria
Assay-based research activities using state-of-the-art molecular technologies, such as digital PCR, real-time PCR, Next-Generation-Sequencing (NGS), microarray-based and isothermal analytical methods
Microarray-based multiparameter serology using antibody arrays, antigen arrays and peptide arrays
Bioinformatics for molecular assay design and evaluation of corresponding data (e.g. NGS)
Translation of existing and new research results into real available products in cooperation with corresponding partners
Building a "bridge" between academic research and the development of new innovative assays using systems technology and product development and realization with cooperating companies in the diagnostics industry.

DNA-based multiparameter methods

The figure shows a typical microarray image after processing. The automated analysis of the dark spots is performed in the analyzer (l.).
Image: AG Ehricht

The Ehricht group started its work in January 2019 and previously, over the past few years, had gained important insights into the development and application of various molecular methods for the detection, epidemiology and understanding of pathogenic bacteria and their antibiotic resistance (MRSA, ESBL, CRE, VRE, etc.). In particular, microarray-based methods and specially developed platforms were used (left figure), which in their entire breadth covered bioinformatic assay design, surface chemistry, manufacturing, test development, image and data evaluation as well as specific applications. Special attention was paid to the implementation of these research results into real existing products and their evolution. On the other hand, the main focus was on developing strategies and procedures for optimal sample preparation and implementing them in complex processes.

Braun SD, Jamil B, Syed MA, Abbasi SA, Weiss D, Slickers P, Monecke S, Engelmann I, Ehricht R: Prevalence of carbapenemase-producing organisms at the Kidney Center of Rawalpindi (Pakistan) and evaluation of an advanced molecular microarray-based carbapenemase assay. Future Microbiol 2018, 13:1225-1246.
Monecke S, Slickers P, Gawlik D, Muller E, Reissig A, Ruppelt-Lorz A, Akpaka PE, Bandt D, Bes M, Boswihi SS et al: Molecular Typing of ST239-MRSA-III From Diverse Geographic Locations and the Evolution of the SCCmec III Element During Its Intercontinental Spread. Front Microbiol 2018, 9:1436.
Weiss D, Gawlik D, Hotzel H, Engelmann I, Mueller E, Slickers P, Braun SD, Monecke S, Ehricht R: Fast, economic and simultaneous identification of clinically relevant Gram-negative species with multiplex real-time PCR. Future Microbiol 2019, 14:23-32.

Next-Generation-Sequencing - A Tool for the Development of Rapid Tests

The MinION (o.l.) developed by Nanopore manages to generate genom reads with lengths up to 100kB using its new pore based sequencing method (diagram below). This makes it possible to assemble full genomes quickly and without gaps (e.g. E. coli BL21).
Image: AG Ehricht

The MinION platform developed by Oxford Nanopore Technologies (Oxford, UK) with its pore technology is regarded as the next step in next-generation sequencing (right). The MinION technology is based on membrane-bound protein nanopores. If a voltage is applied to this membrane, an ion current is generated through the pores. If a DNA strand passes through the pore, voltage changes occur, which are measured and later converted into nucleotides. Up to 400 nucleotides per second can be measured per pore, which can lead to outputs of up to two gigabases per genome. Single reads can reach lengths of 50,000-100,000 bases. Therefore it is possible to analyze and characterize bacterial genomes easily and quickly.

What makes the platform so attractive is its comparably low price and compact size. The Ehricht group therefore wants to use this technology to develop new groundbreaking assays on a molecular basis. However, other methods of next-generation sequencing (e.g. MySeq, Illumina) are also being established and applied.

Stieber B, Sabat A, Monecke S, Slickers P, Akkerboom V, Muller E, Friedrich AW, Ehricht R: PVL overexpression due to genomic rearrangements and mutations in the S. aureus reference strain ATCC25923. BMC Res Notes 2017, 10(1):576.

Protein- and peptide-based multiparameter methods

Routinely, tests for different antigens are separated and performed sequentially, resulting in high costs and delayed results. In addition, a relatively large amount of sample is required. The Ehricht group was able to prove that multiparameter serology can be realised with protein and peptide microarrays. Thus the IgG status and vaccination status for 30 pathogens could be determined in parallel and from 1 µl and a total time of 2h (figure below). The same procedure could be used in the future not only for diagnostic purposes but also for test development (antigen and antibody screening). The antigen panel can be quickly adapted to other applications and also transferred to point-of-care platforms such as lateral flow.

Ehricht R, Adelhelm K, Monecke S, Huelseweh B: Application of protein arraytubes to bacteria, toxin, and biological warfare agent detection. Methods Mol Biol 2009, 509:85-105.
Sachse K, Rahman KS, Schnee C, Muller E, Peisker M, Schumacher T, Schubert E, Ruettger A, Kaltenboeck B, Ehricht R: A novel synthetic peptide microarray assay detects Chlamydia species-specific antibodies in animal and human sera. Sci Rep 2018, 8(1):4701.

Test principle of multiparameter serology using protein and peptide microarrays. Results of the multiparameter tests can be quickly incorporated into applications such as lateral flow.
Image: AG Ehricht