Novel copper-containing ferrite nanoparticles exert lethality to MRSA by disrupting MRSA cell membrane permeability, depleting intracellular iron ions, and upregulating ROS levels

Berberine inhibits the tarO gene to impact MRSA cell wall synthesis

Hospital and community-acquired infections caused by Methicillin-resistant Staphylococcus aureus (MRSA) have emerged as a significant public health challenge, highlighting the urgent need for novel antibiotics. In response, the antibacterial properties of natural products derived from traditional plants are being investigated as potential treatments for multidrug resistance. This study demonstrates the potent antibacterialimoact of Berberine (BBR), a compound derived from traditional Chinese medicine, against the community-associated MRSA (CA-MRSA) strain USA300 LAC. Through a comprehensive series of in vitro antibacterial experiments and gene-level investigations, we discovered that BBR compromises the integrity of the USA300 LAC cell wall structure. This mechanism of action is likely attributed to the inhibition of the tarO gene, which encodes a critical enzyme in the initial stage of wall teichoic acid (WTA) biosynthesis, thereby suppressing WTA synthesis, an essential component of the cell wall. Additionally, BBR upregulates the expression of lytic enzymes LytM and SsaA, resulting in accelerated hydrolysis of peptidoglycan, a major structural element of the cell wall. This disruption ultimately leads to the destruction of the USA300 LAC cell wall. Moreover, combined antibacterial assays reveal that BBR synergistically enhances the antibacterial effect of Oxacillin against USA300 LAC. Overall, our findings elucidate the antibacterial mechanism of BBR, a traditional Chinese medicine monomer, against MRSA and highlight its promising potential for clinical application in the treatment of MRSA.

Design, Synthesis, and Biological Evaluation of 1,3,4-Thiadiazole Derivatives as Novel Potent Peptide Deformylase Inhibitors for Combating Drug-Resistant Gram-Positive and -Negative Bacteria

The prevalence of drug-resistant bacteria is a major challenge throughout the world, especially with respect to Gram-negative bacteria, such as drug-resistant Acinetobacter baumannii, which are regarded as the greatest bacterial threat to human health by the World Health Organization (WHO). In this work, 1,3,4-thiadiazole was introduced into the main skeleton of the classical peptidomimetic peptide deformylase (PDF) inhibitor in pursuit of highly efficient and broad-spectrum bacteriostatic drugs. Upon detailed structure-activity relationship study, PDF inhibitors that possess satisfactory activity against both Gram-positive and Gram-negative bacteria as well as a lower potential for methemoglobin toxicity were screened out. The mechanism of the empowered antibacterial activity against Gram-negative bacteria was also investigated. Finally, for the first time, remarkable protective efficacy against drug-resistant A. baumannii in a mouse model was achieved by a PDF inhibitor (compound 43). These findings can pave a way to new approaches to the development of novel broad-spectrum PDF inhibitors.

Cinnamaldehyde nanoemulsion decorated with rhamnolipid for inhibition of methicillin-resistant Staphylococcus aureus biofilm formation: in vitro and in vivo assessment

Background

Staphylococcus aureus (S. aureus) biofilm associated infections are prevalent and persistent, posing a serious threat to human health and causing significant economic losses in animal husbandry. Nanoemulsions demonstrate significant potential in the treatment of bacterial biofilm associated infections due to their unique physical, chemical and biological properties. In this study, a novel cinnamaldehyde nanoemulsion with the ability to penetrate biofilm structures and eliminate biofilms was developed.

Methods

The formulation of cinnamaldehyde nanoemulsion (Cin-NE) combined with rhamnolipid (RHL) was developed by self-assembly, and the efficacies of this formulation in inhibiting S. aureus biofilm associated infections were assessed through in vitro assays and in vivo experiments by a mouse skin wound healing model.

Results

The particle size of the selected Cin-NE formulation was 13.66 ± 0.08 nm, and the Cin-RHL-NE formulation was 20.45 ± 0.25 nm. The selected Cin-RHL-NE formulation was stable at 4, 25, and 37°C. Furthermore, the Minimum Inhibitory Concentration (MIC) value of Cin-RHL-NE against MRSA was two-fold lower than drug solution. Confocal laser scanning microscopy (CLSM) revealed the superior efficacy of Cin-RHL-NE in eradicating MRSA biofilms while maintaining the Cin's inherent functional properties. The efficacy of Cin-RHL-NE in the mouse skin wound healing model was superior to other formulation.

Conclusion

These findings highlight the potential of the formulation Cin-RHL-NE for eradicating biofilms, and effective in treating notoriously persistent bacterial infections. The Cin-RHL-NE can used as a dosage form of Cin application to bacterial biofilm associated infections.

A Comparative Analysis of the Antibacterial Spectrum of Ultrasmall Manganese Ferrite Nanozymes with Varied Surface Modifications

Bacterial infectious diseases pose a significant global challenge. However, conventional antibacterial agents exhibit limited therapeutic effectiveness due to the emergence of drug resistance, necessitating the exploration of novel antibacterial strategies. Nanozymes have emerged as a highly promising alternative to antibiotics, owing to their particular catalytic activities against pathogens. Herein, we synthesized ultrasmall-sized MnFe2O4 nanozymes with different charges (MnFe2O4-COOH, MnFe2O4-PEG, MnFe2O4-NH2) and assessed their antibacterial capabilities. It was found that MnFe2O4 nanozymes exhibited both antibacterial and antibiofilm properties attributed to their excellent peroxidase-like activities and small sizes, enabling them to penetrate biofilms and interact with bacteria. Moreover, MnFe2O4 nanozymes effectively expedite wound healing within 12 days and facilitate tissue repair and regeneration while concurrently reducing inflammation. MnFe2O4-COOH displayed favorable antibacterial activity against Gram-positive bacteria, with 80% bacterial removal efficiency against MRSA by interacting with phosphatidylglycerol (PG) and cardiolipin (CL) of the membrane. By interacting with negatively charged bacteria surfaces, MnFe2O4-NH2 demonstrated the most significant and broad-spectrum antibacterial activity, with 95 and 85% removal efficiency against methicillin-resistant Staphylococcus aureus (MRSA) and P. aeruginosa, respectively. MnFe2O4-PEG dissipated membrane potential and reduced ATP levels in MRSA and P. aeruginosa, showing relatively broad-spectrum antibacterial activity. To conclude, MnFe2O4 nanozymes offer a promising therapeutic approach for treating wound infections.

Bioactive chitosan/poly(ethyleneoxide)/CuFe2O4 nanofibers for potential wound healing

Wound healing is a complex process that often requires intervention to accelerate tissue regeneration and prevent complications. The goal of this research was to assess the potential of bioactive chitosan@poly (ethylene oxide)@CuFe2O4 (CS@PEO@CF) nanofibers for wound healing applications by evaluating their morphology, mechanical properties, and magnetic behavior. Additionally, in vitro and in vivo studies were conducted to investigate their effectiveness in promoting wound healing treatment. The nanoparticles exhibited remarkable antibacterial and antioxidant properties. In the nanofibrous mats, the optimal concentration of CuFe2O4 was determined to be 0.1% Wt/V. Importantly, this concentration did not adversely affect the viability of fibroblast cells, which also identified the ideal concentration. The scaffold's hemocompatibility revealed nonhemolytic properties. Additionally, a wound-healing experiment demonstrated significant migration and growth of fibroblast cells at the edge of the wound. These nanofibrous mats are applied to treat rats with full-thickness excisional wounds. Histopathological analysis of these wounds showed enhanced wound healing ability, as well as regeneration of sebaceous glands and hair follicles within the skin. Overall, the developed wound dressing comprises CuFe2O4 nanoparticles incorporated into CS/PEO nanofibrous mats demonstrating its potential for successful application in wound treatment.