Monitoring fidaxomicin production: an RP-HPLC-UV approach for the quantification and characterization of fermentation broth

Fidaxomicin, also known as lipiarmycin A3, is a macrocyclic antibiotic used to treat Clostridioides difficile infections and is industrially produced by fermentation from various actinomycetes [ 1 ]. The complexity of fermentation broths requires a detailed analytical approach to monitor both fidaxomicin production and the presence of structurally related impurities. Identifying these by-products is critical for optimizing fermentation conditions and improving both yield and purity.Due to the structural complexity of fidaxomicin and the presence of by-products with similar molecular structures, only a limited number of HPLC methods have been described in the literature [ 2 ]. Therefore, there is a clear need to develop a robust and specific analytical method that ensures batch-to-batch consistency and supports industrial scalability. In this study, we developed an HPLC method to monitor the fermentation process, quantify fidaxomicin, and identify key by-products. This approach provides a valuable tool for process optimization, monitoring, and quality control in the industrial production of fidaxomicin. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany