Mahmoud Abdelkhalek Elfaky

Text: Corrections and Clarifications

Objectives: Marine sponges, such as Dactylospongia metachromia and Suberites aff. clavatus from the Red Sea have emerged as potential sources of bioactive compounds with significant antimicrobial properties. Methods: This study investigates the antibacterial and antibiofilm activities of methanol–dichloromethane extracts from these sponges against clinically relevant strains of Gram-positive bacteria, including Staphylococcus aureus , Methicillin-resistant Staphylococcus aureus , and Staphylococcus epidermidis , as well as Gram-negative pathogens like Pseudomonas aeruginosa and Escherichia coli using agar well diffusion, broth microdilution, biofilm inhibition/eradication assays, scanning electron microscopy (SEM), and LC-MS profiling. Results: The results revealed that the extract of Dactylospongia metachromia exhibited promising antibacterial activity, particularly against Gram-positive strains, with a significant zone of inhibition and moderate bactericidal effects, indicated by MICs of 250 µg/mL for both Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus . In contrast, Suberites aff. clavatus showed minimal antibacterial activity. Additionally, Dactylospongia metachromia demonstrated effective inhibition and eradication of biofilm formation, particularly against Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus . Scanning electron microscope images further revealed rupture of the bacterial membrane. LC-MS tentatively identified smenospongine as a major antibacterial component, while metachromin H and nakijiquinone J showed no reported antimicrobial activity. Suberites aff. clavatus showed minimal activity. Conclusion: These findings suggest that Dactylospongia metachromia could be a valuable source for developing new treatments for skin infections caused by antibiotic-resistant bacteria, while Suberites aff. clavatus may require further exploration for its bioactive compounds. This study highlights the therapeutic potential of Red Sea sponges and supports the need for continued research into marine natural products for antimicrobial drug development.

The journal retracts the article titled “Characterization of the Anti-Biofilm and Anti-Quorum Sensing Activities of the β-Adrenoreceptor Antagonist Atenolol Against Gram-Negative Bacterial Pathogens”

Introduction: Wound treatment is a significant health burden in any healthcare system, which requires proper management to minimize pain and prevent bacterial infections that can complicate the wound healing process. Rationale: There is a need to develop innovative therapies to accelerate wound healing cost-effectively. Herein, two polymer-based nanofibrous systems were developed using poly-lactic-co-glycolic-acid (PLGA) and polyvinylpyrrolidone (PVP) loaded with a combination of an antibiotic (Fusidic acid, FA) and a local anesthetic (Lidocaine, LDC) via electrospinning technique for an expedited healing process by preventing bacterial infections while reducing the pain sensation. Results: The fabricated nanofibers showed an excellent morphology with an average fiber diameter of 556 ± 71 nm and 291 ± 87 nm for the dual drug-loaded PLGA/PVP and PVP nanofibers, respectively. The encapsulation efficiency (EE%) and drug loading (DL) studies revealed that PLGA/PVP loaded with FA and LDC exhibited EE% of 92% and 75%, respectively, while the DL was measured at 40 ± 8 μg/mg for FA and 32 ± 7 μg/mg for LDC. Furthermore, both drugs were fully released from the nanofibers within 48 hours. In contrast, FA/LDC-loaded PVP nanofibers exhibited EE% of 100% for FA and 84% for LDC; DL was measured at 85 ± 3 μg/mg for FA and 70 ± 3 μg/mg for LDC, while both drugs were completely released within 24 hours. The in vitro cytotoxicity study demonstrated a safe concentration of FA and LDC at ≤ 125 μg/mL. The prepared nanofibers were tested in vivo in an S. aureus-infected wound mice model to assess their efficacy, and the results showed that the FA/LDC-PVP had a faster wound closure and the lowest bacterial counts compared to other groups. Conclusion: These findings showed the potential application of the fabricated dual drug-loaded nanofibers as a wound-healing plaster against infected acute wounds.

The rise of antibiotic resistance in bacteria is becoming a global concern, particularly due to the dwindling supply of new antibiotics. This situation mandates the discovery of new antimicrobial candidates. Plant-derived natural compounds have historically played a crucial role in the development of antibiotics, serving as a rich source of substances possessing antimicrobial properties. Numerous studies have supported the reputation of 6-gingerol, a prominent compound found in the ginger family, for its antibacterial properties. In this study, the antibacterial activities of 6-gingerol were evaluated against Gram-negative bacteria, Acinetobacter baumannii and Klebsiella pneumoniae, with a particular focus on the clinically significant Gram-negative Pseudomonas aeruginosa and Gram-positive bacteria Staphylococcus aureus. Furthermore, the anti-virulence activities were assessed in vitro, in vivo, and in silico. The current findings showed that 6-gingerol’s antibacterial activity is due to its significant effect on the disruption of the bacterial cell membrane and efflux pumps, as it significantly decreased the efflux and disrupted the cell membrane of S. aureus and P. aeruginosa. Furthermore, 6-gingerol significantly decreased the biofilm formation and production of virulence factors in S. aureus and P. aeruginosa in concentrations below MICs. The anti-virulence properties of 6-gingerol could be attributed to its capacity to disrupt bacterial virulence-regulating systems; quorum sensing (QS). 6-Gingerol was found to interact with QS receptors and downregulate the genes responsible for QS. In addition, molecular docking, and molecular dynamics (MD) simulation results indicated that 6-gingerol showed a comparable binding affinity to the co-crystalized ligands of different P. aeruginosa QS targets as well as stable interactions during 100 ns MD simulations. These findings suggest that 6-gingerol holds promise as an anti-virulence agent that can be combined with antibiotics for the treatment of severe infections.