High-performance liquid chromatographic identification of beta-lactam antibiotics produced by dermatophytes

Thirteen of 48 dermatophyte isolates were found by bioassay to produce beta-lactam antibiotics and seven produced other antibiotics. Estimation and detection of specific beta-lactams in culture broths by derivatization and HPLC was only possible following concentration and extraction procedures. Analysis of the concentrated broths demonstrated the production of penicillin X and penicillin G by two Trichophyton mentagrophytes strains and by one Microsporum canis strain; one further T. mentagrophytes strain produced only penicillin X. Additions of the beta-lactam side-chain precursors, phenylacetic acid and phenoxyacetic acid, to fermentation media failed to increase the antibiotic titres.