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PurposeStaphylococcus aureus is the most common persistent pathogen in humans, so development of new formulations to combat pathogen invasion is quite necessary.MethodsIn the current study, for the first time, the synergistic activity of recombinant lysostaphin and LL-37 peptide was studied against S. aureus. Moreover, different niosomal formulations of the peptide and protein were prepared and analyzed in terms of size, shape, zeta potential, and entrapment efficiency. Also, a long-term antibacterial activity of the best niosomal formulation and free forms was measured against S. aureus in vitro.ResultsThe optimal niosomal formulation was obtained by mixing the surfactants (span60 and tween60; 2:1 w/w), cholesterol, and dicetylphosphate at a ratio of 47:47:6, respectively. They showed uniform spherical shapes with the size of 565 and 325 nm for lysostaphin and LL-37, respectively. This formulation showed high entrapment efficiency for the peptide, protein, and a slow-release profile over time. Release kinetic was best fitted by Higuchi model indicating a diffusion-based release of the drugs. The lysostaphin/LL-37 niosomal formulation synergistically inhibited growth of S. aureus for up to 72 hours. However, the same amounts of free forms of both anti-microbial agents could not hold the anti-microbial effect and growth was seen in the following 72 hours. Cytotoxicity assay specified that lysostaphin/LL-37 niosomal combination had no deleterious effect on normal fibroblast cells at effective antimicrobial concentrations.ConclusionThis study indicated that the use of lysostaphin in combination with LL-37, either in niosomal or free forms, synergistically inhibited growth of S. aureus in vitro. In addition, niosomal preparation of antimicrobial agents could provide a long-term protection against bacterial infections.

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Leishmaniasis is a worldwide uncontrolled parasitic disease due to the lack of effective drug and vaccine. To speed up effective drug development, we need powerful methods to rapidly assess drug effectiveness against the intracellular form of Leishmania in high throughput assays. Reporter gene technology has proven to be an excellent tool for drug screening in vitro. The effects of reporter proteins on parasite infectivity should be identified both in vitro and in vivo. In this research, we initially compared the infectivity rate of recombinant Leishmania major expressing stably enhanced green fluorescent protein (EGFP) alone or EGFP-luciferase (EGFP-LUC) with the wild-type strain. Next, we evaluated the sensitivity of these parasites to amphotericin B (AmB) as a standard drug in 2 parasitic phases, promastigote and amastigote. This comparison was made by MTT and nitric oxide (NO) assay and by quantifying the specific signals derived from reporter genes like EGFP intensity and luciferase activity. To study the amastigote form, both B10R and THP-1 macrophage cell lines were infected in the stationary phase and were exposed to AmB at different time points. Our results clearly revealed that the 3 parasite lines had similar in vitro infectivity rates with comparable parasite-induced levels of NO following interferon-γ/lipopolysaccharide induction. Based on our results we proposed the more reporter gene, the faster and more sensitive evaluation of the drug efficiency.