CHARACTERIZATION OF THE ANTIMICROBIAL AND ANTIBIOFILM EFFECT OF CU-FENDIONA AND AG-FENDIONA ON MULTI-RESISTANT STRAINS OF KLEBSIELLA PNEUMONIAE
Name: GABRIELA SEABRA
Publication date: 04/09/2025
Examining board:
Name |
Role |
|---|---|
| EDSON OLIVEIRA DELATORRE | Examinador Interno |
| QUÉZIA MOURA DA SILVA | Examinador Interno |
| TATIANA DE CASTRO ABREU PINTO | Examinador Externo |
| VALÉRIA DE ALMEIDA | Examinador Externo |
Summary: Infections caused by multidrug-resistant (MDR) Klebsiella pneumoniae strains are related to prolonged hospitalization, higher mortality and increased treatment costs, representing a global challenge for healthcare systems. Studies conducted by our research group and collaborators have indicated that Ag-phendione and Cu-phendione, coordination compounds derived from 1,10-phenanthroline, hold promise as antimicrobial and antibiofilm agents, and as virulence attenuators in Gram-negative bacilli. In this study, we characterized the antimicrobial and antibiofilm activities of these compounds against MDR K. pneumoniae strains. To investigate potential mechanisms of action, proteomic analysis was performed using nano-liquid chromatography coupled with mass spectrometry (nanoESI-LC MS/MS). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 50 g/mL (51.81 M) for Cu-phendione and 12.5 g/mL (19.91 M) for Ag-phendione. Time-kill assays suggest a bactericidal activity of these compounds with 3-12 hours in combination with meropenem in subinhibitory concentrations. At 0.5 MIC, Ag-phendione and Cu-phendione reduced biofilm formation by 28.54% (p = 0.013) and 34.87% (p = 0.008), respectively. Cu-phendione also disrupted preformed biofilms by 45.30% (2× MIC) and 52.57% (4× MIC), while Ag-phendione produced reductions of 30.08% and 40.26% at the same concentrations. Virulence was evaluated in vivo using a Galleria mellonella infection model, with larval survival assessed at different inoculum levels (10, 10, and 10 CFU/larva). The most virulent strain (NCTC 13368) was selected to test the antimicrobial effect of the compounds. Using an inoculum of 10 CFU/larva, larval survival increased significantly in groups treated with Ag-phendione (0.5 MIC) + MPM (0.5 MIC) and Cu-phendione (0.5 MIC) + MPM (0.5 MIC), compared to untreated larvae. Proteomic analysis identified 606 proteins with at least one unique peptide, of which 23 were modulated by Ag-fendione and 17 by Cu-fendione. Downregulated proteins include NH3-dependent NAD+ synthetase, a RepFiA replicon protein and trehalose-6-phosphate hydrolase; while upregulated proteins include acid phosphatase and the beta-clamp protein. Overall, the modulated proteins were associated with NAD synthesis, plasmid partitioning, carbohydrate and DNA metabolism, and redox activity. These processes are related to capsule and biofilm formation, metabolism and replication, important factors for bacterial colonization and infection. Therefore, the modulation of these proteins may be related to the antimicrobial and antibiofilm activity of Ag-phendione and Cu-phendione against K. pneumoniae MDR strains.
