Novel fluorescent cephalosporins: Synthesis, antimicrobial activity and photodynamic inactivation of antibiotic resistant bacteria

Abstract Two novel fluorescent cephalosporins, TCA and TBCA , were synthesized and characterized by 1 H NMR, 13 C NMR, UV–vis, and fluorescence spectroscopies. Biological activity assays demonstrated that TCA inactivated a Klebsiella pneumonia strain that expressed extended-spectrum β-lactamases. Incubation of 6 μM TCA with K. pneumonia cultures resulted in cell death for 84% of the cells after 126 J/cm 2 of light irradiation. In vitro , TCA exhibited a MIC = 0.5 μg/mL with Staphylococcus aureus . Kinetic evaluation revealed that TCA and TBCA were substrates for B1 and B3 subclass metallo-β-lactamases. TBCA exhibited stronger binding affinities to the Gram-positive bacterial strains MRSA1, MRSA2, and S. aureus with value of 2.95–6.59 μM per 10 8  cells/mL.