The worldwide escalation of bacterial resistance to conventional medical antibiotics is a serious concern for modern medicine. High prevalence of multidrug-resistant bacteria among bacteria-based infections decreases effectiveness of current treatments and causes thousands of deaths. New improvements in present methods and novel strategies are urgently needed to cope with this problem. Owing to their antibacterial activities, metallic nanoparticles represent an effective solution for overcoming bacterial resistance. However, metallic nanoparticles are toxic, which causes restrictions in their use. Recent studies have shown that combining nanoparticles with antibiotics not only reduces the toxicity of both agents towards human cells by decreasing the requirement for high dosages but also enhances their bactericidal properties. Combining antibiotics with nanoparticles also restores their ability to destroy bacteria that have acquired resistance to them. Furthermore, nanoparticles tagged with antibiotics have been shown to increase the concentration of antibiotics at the site of bacterium-antibiotic interaction, and to facilitate binding of antibiotics to bacteria. Likewise, combining nanoparticles with antimicrobial peptides and essential oils generates genuine synergy against bacterial resistance. In this article, we aim to summarize recent studies on interactions between nanoparticles and antibiotics, as well as other antibacterial agents to formulate new prospects for future studies. Based on the promising data that demonstrated the synergistic effects of antimicrobial agents with nanoparticles, we believe that this combination is a potential candidate for more research into treatments for antibiotic-resistant bacteria.

Nanotechnology is the creation of functional materials, devices and systems at atomic and molecular scales (1-100 nm), where properties differ significantly from those at a larger scale. The use of nanotechnology and nanomaterials in medical research is growing rapidly. Recently, nanotechnologic developments in microbiology have gained importance in the field of chemotherapy. Bacterial strains that are resistant to current antibiotics have become serious public health problems that raise the need to develop new bactericidal materials. Metal oxide nanoparticles, especially TiO(2) and Ag(2)O nanoparticles, have demonstrated significant antibacterial activity. Therefore, it is thought that this property of metal oxide nanoparticles could effectively be used as a novel solution strategy. In this review, we focus on the unique properties of nanoparticles, their mechanism of action as antibacterial agents and recent studies in which the effects of visible and UV-light induced TiO(2) and Ag(2)O nanoparticles on drug-resistant bacteria have been documented. In addition, from to previous results of our studies, antileishmanial effects of metal oxide nanoparticles are also demonstrated, indicating that metal oxide nanoparticles can also be effective against eukaryotic infectious agents. Conversely, despite their significant potential in antimicrobial applications, the toxicity of metal oxide nanoparticles restricts their use in humans. However, recent studies infer that metal oxide nanoparticles have considerable potential to be the first-choice for antibacterial and antiparasitic applications in the future, provided that researchers can bring new ideas in order to cope with their main problem of toxicity.

Leishmaniasis is a protozoan vector-borne disease and is one of the biggest health problems of the world. Antileishmanial drugs have disadvantages such as toxicity and the recent development of resistance. One of the best-known mechanisms of the antibacterial effects of silver nanoparticles (Ag-NPs) is the production of reactive oxygen species to which Leishmania parasites are very sensitive. So far no information about the effects of Ag-NPs on Leishmania tropica parasites, the causative agent of leishmaniasis, exists in the literature. The aim of this study was to investigate the effects of Ag-NPs on biological parameters of L. tropica such as morphology, metabolic activity, proliferation, infectivity, and survival in host cells, in vitro. Consequently, parasite morphology and infectivity were impaired in comparison with the control. Also, enhanced effects of Ag-NPs were demonstrated on the morphology and infectivity of parasites under ultraviolet (UV) light. Ag-NPs demonstrated significant antileishmanial effects by inhibiting the proliferation and metabolic activity of promastigotes by 1.5- to threefold, respectively, in the dark, and 2- to 6.5-fold, respectively, under UV light. Of note, Ag-NPs inhibited the survival of amastigotes in host cells, and this effect was more significant in the presence of UV light. Thus, for the first time the antileishmanial effects of Ag-NPs on L. tropica parasites were demonstrated along with the enhanced antimicrobial activity of Ag-NPs under UV light. Determination of the antileishmanial effects of Ag-NPs is very important for the further development of new compounds containing nanoparticles in leishmaniasis treatment.

A sensitive microcapillary culture method (MCM) was developed for rapid diagnosis of cutaneous leishmaniasis (CL). The MCM is superior to the traditional culture method (TCM) as determined by the smaller inoculum size, the higher sensitivity for detection of promastigotes, and the more rapid time for emergence of promastigotes. With lesion amastigote loads from grade III to 0, the positive rates and the periods for promastigote emergence were 3-4-fold higher and faster with the MCM than with the TCM, e.g., 83-97% positive in 4-7 days versus 20-40% positive in 15-30 days (P = 0.0001). The higher Pco(2) and lower Po(2) and pH presumably encourage a rapid amastigote-to-promastigote differentiation and/or the survival or growth of the latter. This MCM has the advantage of simplicity, and may be suitable for diagnostic use and for parasite retrieval in many other endemic sites where parasites are known to be difficult to grow.

BackgroundCanine parvovirus 2 (CPV-2) remains a significant worldwide canine pathogen and the most common cause of viral enteritis in dogs. The 1 L15 and 7 L15 peptides overlap each other with QPDGGQPAV residues (7-15 of VP2 capsid protein of CPV) is shown to produce high immune response. PLGA nanoparticles were demonstrated to have special properties such as; controlled antigen release, protection from degradation, elimination of booster-dose and enhancing the cellular uptake by antigen presenting cells. Nevertheless, there is no study available in literature, about developing vaccine based on PLGA nanoparticles with adjuvant properties against CPV.Thus, the aim of the present study was to synthesize and characterize high immunogenic W-1 L19 peptide (from the VP2 capsid protein of CPV) loaded PLGA nanoparticle and to evaluate their in vitro immunogenic activity.ResultsPLGA nanoparticles were produced with 5.26 ± 0.05 % loading capacity and high encapsulation efficiency with 81.2 ± 3.1 %. Additionally, it was evaluated that free NPs and W-1 L19 peptide encapsulated PLGA nanoparticles have Z-ave of 183.9 ± 12.1 nm, 221.7 ± 15.8 nm and polydispersity index of 0.107 ± 0.08, 0.135 ± 0.12 respectively. It was determined that peptide loaded PLGA nanoparticles were successfully phagocytized by macrophage cells and increased NO production at 2-folds (*P < 0.05) in contrast to free peptide, and 3-folds (*P < 0.01) in contrast to control.ConclusionIn conclusion, for the first time, W-1 L19 peptide loaded PLGA nanoparticles were successfully synthesized and immunogenic properties evaluated. Obtained results showed that PLGA nanoparticles enhanced the capacity of W-1 L19 peptide to induce nitric oxide production in vitro due to its adjuvant properties. Depend on the obtained results, these nanoparticles can be accepted as potential vaccine candidate against Canine Parvovirus. Studies targeting PLGA nanoparticles based delivery system must be maintained in near future in order to develop new and more effective nano-vaccine formulations.