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Abstract We aim to assess the antibacterial and anti-biofilm properties of Niosome-encapsulated Imipenem. After isolating Staphylococcus epidermidis isolates and determining their microbial sensitivity, their ability to form biofilms was examined using plate microtiter assay. Various formulations of Niosome-encapsulated Imipenem were prepared using the thin-film hydration method, Minimum Biofilm Inhibitory Concentration (MBIC) and Minimum Inhibitory Concentration (MIC) were determined, and biofilm genes expression was examined. Drug formulations’ toxicity effect on HDF cells were determined using MTT assay. Out of the 162 separated S. epidermidis, 106 were resistant to methicillin. 87 MRSE isolates were vancomycin-resistant, all of which could form biofilms. The F1 formulation of niosomal Imipenem with a size of 192.3 ± 5.84 and an encapsulation index of 79.36 ± 1.14 was detected, which prevented biofilm growth with a BGI index of 69% and reduced icaD, FnbA, EbpS biofilms’ expression with P ≤ 0.001 in addition to reducing MBIC and MIC by 4–6 times. Interestingly, F1 formulation of niosomal Imipenem indicated cell viability over 90% at all tested concentrations. The results of the present study indicate that Niosome-encapsulated Imipenem reduces the resistance of MRSE to antibiotics in addition to increasing its anti-biofilm and antibiotic activity, and could prove useful as a new strategy for drug delivery.

Melittin is a natural toxin used in traditional medicine as an anti-inflammatory drug. It seems that the anti-inflammatory properties of melittin are caused by suppressing the expression of inflammatory genes and inhibiting signaling pathways. However, the use of melittin is limited due to instability, rapid degradation, and impurity. The aim of this study was to investigate the intranasal administration of a melittin-encoded plasmid as a new melittin delivery method for allergic diseases. After the induction of a mouse model of allergic rhinitis, mice received intranasal melittin plasmid. After the final challenge with allergen and allergic symptom assessment, the required samples were collected and transforming growth factor-beta (TGF-β), interferon-gamma (IFN-γ), and interleukin-4 (IL-4) cytokine levels, serum levels of ovalbumin-specific immunoglobulin (Ig) E, and histopathological changes were assessed. In addition to investigating the immune response, the effect of melittin on the expression level of genes involved in apoptosis was also investigated. The melittin plasmid significantly improved nasal symptoms and decreased eosinophil infiltration into the nasal mucosa. Moreover, melittin decreased the expression levels of IL-4 and TGF-β in nasal lavage fluid, while IFN-γ expression was increased. Regarding the expression level of genes involved in apoptosis, melittin led to an increase in BAX mRNA expression. These results suggest intranasal administration of a plasmid encoding melittin can suppress nasal symptoms, eosinophil infiltration, and immunomodulation of the immune response, which can be considered a promising approach in the treatment of inflammatory diseases.