Not Only Antimicrobial: Metronidazole Mitigates the Virulence of Proteus mirabilis Isolated from Macerated Diabetic Foot Ulcer

Abstract

Diabetic foot ulcers are recognized to be a severe complication of diabetes, increasing the risk of amputation and death. The bacterial infection of Diabetic foot ulcers with virulent and resistant bacteria as Proteus mirabilis greatly worsens the wound and may not be treated with conventional therapeutics. Developing new approaches to target bacterial virulence can be helpful to conquer such infections. In the current work, we evaluated the anti-virulence activities of the widely used antibacterial metronidazole. The minimum inhibitory concentrations (MIC) and minimum biofilm eradication concentrations (MEBC) were determined for selected antibiotics which P. mirabilis was resistant to them in the presence and absence of metronidazole in sub-MIC. The effect of metronidazole in sub-MIC on P. mirabilis virulence factors as production of exoenzymes, motilities, adhesion and biofilm formation, were evaluated. Furthermore, molecular docking of metronidazole into P. mirabilis adhesion and essential quorum sensing (QS) proteins, was performed. The results revealed a significant ability of metronidazole to in-vitro inhibit P. mirabilis virulence factors and antagonize its essential proteins. Moreover, metronidazole markedly decreased the MICs and MBECs of tested antibiotics. Conclusively, metronidazole in sub-MIC is a plausible anti-virulence and anti-QS agent that can be combined to other antibiotics as anti-virulence adjuvant to defeat aggressive infections.

A Novel Use of Allopurinol as A Quorum-Sensing Inhibitor in Pseudomonas aeruginosa

“…In this context and because of their safety, many studies have screened various FDA-approved drugs as QS inhibitors. This hypothesis has been proven in our previous studies [ 6 , 19 , 20 , 23 , 25 , 26 ].…”

“…The quorum-sensing (QS) system plays the most crucial roles in orchestrating the expression of virulence factors associated with numerous pathogenic phenotypes such as bacterial adherence and biofilm formation [ 13 , 22 , 25 , 35 ]. Inhibition of QS is an attractive approach and is considered a novel solution to the problem of antibiotic resistance development [ 24 , 26 ]. Interference with QS is mostly achieved by targeting the binding of signaling molecules to the receptors by competitive inhibition.…”

“…The MIC of allopurinol against P. aeruginosa PAO1 and C. violaceum CV026 were determined by the broth microdilution method according to the Clinical Laboratory and Standards Institute Guidelines (CLSI, 2015) [ 6 , 26 ]. Several dilutions of allopurinol (32, 16, 8, 4, 2, 1, 0.5, and 0.25 mg/mL) were prepared in Mueller–Hinton broth by two-fold serial dilution.…”

“…The interest in repurposing approved drugs to target bacterial QS and virulence has increased over the last few years. In this context, we screened the anti-QS activities of several approved drugs [ 6 , 19 , 20 , 24 , 25 , 26 ]. The non-purine “allopurinol” is a xanthine oxidoreductase selective inhibitor that is clinically employed in the treatment of gout, as it diminishes the urate concentration [ 27 , 28 ].…”

Alteration of Salmonella enterica Virulence and Host Pathogenesis through Targeting sdiA by Using the CRISPR-Cas9 System

“…Monolayers of HeLa cells were cultured in 24-well plates in DMEM medium [46,47]. HeLa cells were passaged with 70% confluent and washed with sterile PBS before adhesion assay.…”