The DiabKON consortium project “Diagnostic Test for Rational Antibiotic Therapy Control” was carried out by CANDOR Bioscience GmbH from 1 June 2019 to 31 May 2023 under the German Federal Ministry of Education and Research (BMBF) funding programme KMU‑innovativ: Medizintechnik (grant number 13GW0354C). The subproject focused on the research and implementation of individual stabilisation solutions for all biocomponents of ligand‑based assays and on the design of a sample‑dilution buffer that would minimise interference from real patient samples. The project was led by Dr Peter Rauch, with Dr Carina Vogt co‑authoring the report.
The technical work began with the procurement of antibodies, peptides, conjugates and antibiotic standards from U.S. suppliers, including anti‑ciprofloxacin and anti‑piperacillin antibodies, HRP‑conjugated antigens, BSA conjugates and pure antibiotic powders. These materials were used to build model assays in both antigen‑coating and antibody‑coating formats. The assays were then subjected to a systematic evaluation of stabilisation formulations and blocking solutions. Long‑term stability studies were performed, and the buffers were continuously refined to achieve a target shelf life of one to two years while maintaining assay precision. Parallel experiments with real patient samples and human serum spiked with the target antibiotics were conducted to assess cross‑reactivity, masking effects and the effectiveness of the dilution buffer in reducing matrix interference.
The outcome of the project was the successful development of stabilisation buffers and sample‑dilution solutions for five clinically relevant antibiotics: ciprofloxacin, piperacillin, linezolid, vancomycin and ceftazidime. These buffers were transferred to the consortium partner DRG Instruments for further testing and validation. The selected formulations were incorporated into CANDOR’s quality management system, which complies with DIN EN ISO 13485:2016 and DIN EN ISO 9001:2015, ensuring that the kits can be produced with consistent quality over the required shelf life. The project therefore provides a foundation for the first ligand‑based therapeutic drug monitoring assays for antibiotics that currently lack such tests, potentially enabling broader access to TDM in smaller laboratories that cannot afford expensive LC‑MS/MS instrumentation.
Collaboration within the DiabKON consortium was essential. CANDOR worked closely with DRG Instruments, the consortium leader, coordinating assay development and validation. The project also involved BioLAGO e.V., a life‑science network that supported external communication and press work for the consortium. The consortium structure facilitated the exchange of biocomponents, technical expertise and validation data, while the BMBF funding under the KMU‑innovativ programme provided the financial resources necessary for the four‑year effort. The report, authored by Dr Carina Vogt and Dr Peter Rauch, documents the scientific progress and the collaborative framework that enabled the successful delivery of stabilisation solutions and assay buffers for rational antibiotic therapy control.