Drug-resistant Strains Of Bacteria Research Articles

Selenium-silk microgels as antifungal and antibacterial agents.

Antimicrobial resistance is a leading threat to global health. Alternative therapeutics to combat the rise in drug-resistant strains of bacteria and fungi are thus needed, but the development of new classes of small molecule therapeutics has remained challenging. Here, we explore an orthogonal approach and address this issue by synthesising micro-scale, protein colloidal particles that possess potent antimicrobial properties. We describe an approach for forming silk-based microgels that contain selenium nanoparticles embedded within the protein scaffold. We demonstrate that these materials have both antibacterial and antifungal properties while, crucially, also remaining highly biocompatible with mammalian cell lines. By combing the nanoparticles with silk, the protein microgel is able to fulfill two critical functions; it protects the mammalian cells from the cytotoxic effects of the bare nanoparticles, while simultaneously serving as a carrier for microbial eradication. Furthermore, since the antimicrobial activity originates from physical contact, bacteria and fungi are unlikely to develop resistance to our hybrid biomaterials, which remains a critical issue with current antibiotic and antifungal treatments. Therefore, taken together, these results provide the basis for innovative antimicrobial materials that can target drug-resistant microbial infections.

Pandemics of Sexually Transmitted Infections (STIs): Clinical Use of Ezrin Peptide Therapy in Russia to Treat and Prevent Candida, Chlamydia, Trichomonas vaginalis, Syphilis, HPV and Herpes (HSV-1 & 2)

There is a global problem of increasing incidence and prevalence of sexually transmitted infection (affecting more than ten percent of the world population), and there is a growing problem of drug and vaccine resistant infections: human ezrin peptide therapy presents a novel solution. This review summarizes the results of 17 clinical trials on the use of human ezrin peptide one (HEP-1 “Gepon”), a 14 amino acid adaptive immunity amplifying peptide registered as a pharmaceutical, which has been in use in the Russian Federation since 2001, for the treatment of a broad spectrum of sexually transmitted diseases caused by infections of bacteria, viruses, fungi and protozoans. HEP-1 and RepG3 (a derivative of HEP-1) have also been successfully used to treat SARS-CoV-2 infection. The high prevalence of chlamydia, candida, Trichomonas vaginalis, Herpes (HSV-1 & HSV-2), Human Papilloma Virus (HPV) are the result of pandemics of sexually transmitted infections (STIs) that are generally increasing world-wide, particularly in women. Although treatments or vaccines are available for the various infections, the current medical interventions have not significantly reduced the growing problem. Multi-drug resistant bacterial & viral strains, and increasing sexual promiscuity are adding to the problem, so new solutions are required. In the Russian Federation, human ezrin peptide therapy with HEP-1 (brand name “Gepon”) is used to treat candida, chlamydia, Trichomonas vaginalis, herpes, and HPV infection. In addition HEP-1 (Gepon) has been shown to be effective in combination with antibiotics, for the treatment of Syphilis. Ezrin peptides induce biological responses in patients to achieve the same or better treatment results than anti-biotic, anti-fungal, anti-viral and anti-protozoan pharmaceuticals, as well as enhancing adaptive protective immune responses like a vaccine. Ezrin peptides can be used as a post-infection vaccination strategy against re-infection. Human Ezrin Peptides can also overcome the rapidly growing problem of drug resistant strains of bacteria, protozoa and viruses. In addition, ezrin peptides amplify adaptive immune responses while simultaneously inhibiting expression of IL-1b, IL-6, IL-8 and TNFa, quickly supressing mucosal inflammation. Human Ezrin Peptides also stimulate fibroblasts to repair damaged tissues.

Multidrug-Resistant Organism Infections of Inpatients in a Hospital in Eastern China from 2015 to 2021.

The prevalence of multidrug-resistant organisms (MDRO) is gradually increasing in the global scope, causing serious burden to patients and society, which is an important public health problem. To analyze the distribution and trend of MDROs and provide a reference for hospital infection control. Collected data on MDROs infections among inpatients in a Grade III Level A hospital in Suzhou from 2015 to 2021, including drug-resistant bacteria strains and specimen sources, etc. Mantel-Haenszel χ2 test was used to evaluate the trend of infection rates over the years and SPSS version 26.0 was used for statistics analysis. The hospital infection rate showed an overall downward trend across the seven-year period, ranging from 1.53% to 2.10%. According to the analysis of change of drug-resistant bacteria strains, the highest infection rate was carbapenem-resistant Acinetobacter baumannii (CRABA) (63.74%), followed by methicillin-resistant Staphylococcus aureus (MRSA) (46.37%), carbapenem-resistant Pseudomonas aeruginosa (CRPAE) (24.87%), carbapenem-resistant Enterobacteriaceae (CRE) (13.14%) and vancomycin-resistant Enterococcus (VRE) (0.42%). The results of Mantel-Haenszel χ2 test showed that there was a linear relationship between the detection rate of CRE and CRPAE and the time (P<0.001), but the correlation was not strong (R = 0.136; R = 0.139). The overall detection rate of the five pathogens also increased (P<0.001). The majority of the specimens, mainly from sputum, airway secretions, and midstream urine, had a detection rate of over 70%. Our data showed that the detection rate of MDROs generally increased from 2015 to 2021, although the hospital infection rate displayed a declining trend. Among the detection rate MDROs, the highest was CRABA, and the lowest was VRE. It is necessary to enhance the prevention, control, and management of MDROs infections in the clinical practice.

Synthetic Cationic Lipopeptide Can Effectively Treat Mouse Mastitis Caused by Staphylococcus aureus

Mastitis caused by Staphylococcus aureus (S. aureus) in dairy cows is one of the most common clinical diseases in dairy cattle. Unfortunately, traditional antibiotic treatment has resulted in the emergence of drug-resistant strains of bacteria, making this disease more difficult to treat. Therefore, novel lipopeptide antibiotics are becoming increasingly important in treating bacterial diseases, and developing novel antibiotics is critical in controlling mastitis in dairy cows. We designed and synthesized three cationic lipopeptides with palmitic acid, all with two positive charges and dextral amino acids. The lipopeptides’ antibacterial activity against S. aureus was determined using MIC and scanning electron microscopy. The safety concentration range of lipopeptides for clinical usage was then estimated using the mouse erythrocyte hemolysis assay and CCK8 cytotoxicity. Finally, lipopeptides with high antibacterial activity and minimal cytotoxicity were selected for the treatment experiments regarding mastitis in mice. The observation of histopathological changes, bacterial tissue load and expression of inflammatory factors determined the therapeutic effects of lipopeptides on mastitis in mice. The results showed that all three lipopeptides displayed some antibacterial activity against S. aureus, with C16dKdK having a strong antibacterial impact and being able to treat the mastitis induced by S. aureus infection in mice within a safe concentration range. The findings of this study can be used as a starting point for the development of new medications for the treatment of mastitis in dairy cows.

An ensemble method for prediction of phage-based therapy against bacterial infections.

Phage therapy is a viable alternative to antibiotics for treating microbial infections, particularly managing drug-resistant strains of bacteria. One of the major challenges in designing phage-based therapy is to identify the most appropriate potential phage candidate to treat bacterial infections. In this study, an attempt has been made to predict phage-host interactions with high accuracy to identify the potential bacteriophage that can be used for treating a bacterial infection. The developed models have been created using a training dataset containing 826 phage- host interactions, and have been evaluated on a validation dataset comprising 1,201 phage-host interactions. Firstly, alignment-based models have been developed using similarity between phage-phage (BLASTPhage), host-host (BLASTHost) and phage-CRISPR (CRISPRPred), where we achieved accuracy between 42.4-66.2% for BLASTPhage, 55-78.4% for BLASTHost, and 43.7-80.2% for CRISPRPred across five taxonomic levels. Secondly, alignment free models have been developed using machine learning techniques. Thirdly, hybrid models have been developed by integrating the alignment-free models and the similarity-scores where we achieved maximum performance of (60.6-93.5%). Finally, an ensemble model has been developed that combines the hybrid and alignment-based models. Our ensemble model achieved highest accuracy of 67.9, 80.6, 85.5, 90, and 93.5% at Genus, Family, Order, Class, and Phylum levels on validation dataset. In order to serve the scientific community, we have also developed a webserver named PhageTB and provided a standalone software package (https://webs.iiitd.edu.in/raghava/phagetb/) for the same.

Synthesis and Biological Evaluation of New Schiff Bases Derived from 4-Amino-5-(3-fluorophenyl)-1,2,4-triazole-3-thione.

The treatment of infectious diseases is a challenging issue faced by the medical community. The emergence of drug-resistant strains of bacteria and fungi is a major concern. Researchers and medical professionals are working to develop new and innovative treatments for infectious diseases. Schiff bases are one a promising class of compounds. In this work, new derivatives were obtained of the 4-amino-5-(3-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione reaction, with corresponding benzaldehydes with various substituents at position 4. The antibacterial and antifungal activities of all synthesized compounds were tested. Several new substances have shown moderate antifungal activity against Candida spp. The highest activity directed against C. albicans was shown by compound RO4, with a 4-methoxyphenyl moiety and an MIC value of 62.5 µg/mL. In order to check the toxicity of the synthesized compounds, their effect on cell lines was examined. Additionally, we tried to elucidate the mechanism of the antibacterial and antifungal activity of the tested compounds using molecular docking to topoisomerase IV, D-Alanyl-D-Alanine Ligase, and dihydrofolate reductase.

Antimicrobial Photodynamic Therapy for the Remote Eradication of Bacteria.

The emergence of multi-drug resistant bacteria strains has been an uphill battle in modern healthcare worldwide, due to the increasing difficulty of killing them. The evolving pathogenicity of bacteria has led to researchers searching for more effective antimicrobial therapeutics to successfully eliminate them without undesirable consequences to the human body. In recent years, antimicrobial photodynamic therapy (APDT), an obsolete technique for cancer treatments, has been reported to eradicate bacteria and biofilm-related infections. The principle of antimicrobial photodynamic therapy solely relies on the photosensitizers (PSs) generating reactive oxygen species, in the presence of oxygen and light, to destroy pathogens. Thus, it can target a broad spectrum of microorganisms, owing to the indirect interaction between PSs and the bacteria, resulting in the less likelihood for the development of drug resistant bacteria strains. This review will focus on the recent progress of APDT in the last five years and some future perspectives of APDT. The mechanism of APDT against bacteria and biofilms, various PSs used for APDT, and some common multidrug-resistant bacteria strains will be briefly introduced. The reported in vivo applications of APDT in the several types of bacterial infections that includes periodontitis, wound infections, keratitis, endophthalmitis and tuberculosis in the last five years will be summarized in detail.

Advances in the field of phage-based therapy with special emphasis on computational resources.

In the current era, one of the major challenges is to manage the treatment of drug/antibiotic-resistant strains of bacteria. Phage therapy, a century-old technique, may serve as an alternative to antibiotics in treating bacterial infections caused by drug-resistant strains of bacteria. In this review, a systematic attempt has been made to summarize phage-based therapy in depth. This review has been divided into the following two sections: general information and computer-aided phage therapy (CAPT). In the case of general information, we cover the history of phage therapy, the mechanism of action, the status of phage-based products (approved and clinical trials) and the challenges. This review emphasizes CAPT, where we have covered primary phage-associated resources, phage prediction methods and pipelines. This review covers a wide range of databases and resources, including viral genomes and proteins, phage receptors, host genomes of phages, phage-host interactions and lytic proteins. In the post-genomic era, identifying the most suitable phage for lysing a drug-resistant strain of bacterium is crucial for developing alternate treatments for drug-resistant bacteria and this remains a challenging problem. Thus, we compile all phage-associated prediction methods that include the prediction of phages for a bacterial strain, the host for a phage and the identification of interacting phage-host pairs. Most of these methods have been developed using machine learning and deep learning techniques. This review also discussed recent advances in the field of CAPT, where we briefly describe computational tools available for predicting phage virions, the life cycle of phages and prophage identification. Finally, we describe phage-based therapy's advantages, challenges and opportunities.

Optimization and evaluation of anticancer, antifungal, catalytic, and antibacterial activities: Biosynthesis of spherical-shaped gold nanoparticles using Pistacia vera hull extract (AuNPs@PV)

In the past years, use of plant sources for the biosynthesis of nanoparticles has become very important. Gold nanoparticles with unique biological properties are one of these materials which are being investigated extensively. In the present study, the aqueous extract of Pistacia vera hull was utilized to fabrication of gold nanoparticles (AuNPs@PV) in a facile, environmentally friendly, and affordable way. Then the anticancer, antifungal, antibacterial, and photocatalytic potentials of AuNPs@PV were also investigated. The results of various techniques applied, including XRD, UV–vis, TEM, FT-IR, EDS, and FESEM showed the biological reduction of Au3+ ions to Au0. Antibacterial studies were performed on a wide range of bacteria including seven strains of ATCC and seven strains of drug-resistant pathogens. According to the findings of this research, it seems that biosynthesized gold nanoparticles had good antibacterial activity against ATCC and drug-resistant strains of bacteria. The MIC values of E. coli, S. aureus, P. mirabilis, P. aeruginosa, E. faecalis, K. pneumonia, A. baumannii were 34.37, 4.2, 8.59, 4.29, 0.5, 34.37, and 8.59 μg/mL, respectively. The result of the antifungal investigation showed that two pathogenic fungi, Candida albicans (IFRC1873) and Candida albicans (IFRC1874) were susceptible to AuNPs@PV with MIC values of 550 and 137 μg/mL, respectively. Furthermore, AuNPs@PV revealed noteworthy anticancer efficacy against AGS-3 and MCF-7 cell lines with IC50 values of 58.31 and 148.1 μg/mL, respectively. The results of the cytotoxicity effect of AuNPs@PV on BEAS-2B as a normal cell line indicated the selectivity of AuNPs@PV on cancerous cells. Furthermore, the fabricated AuNPs@PV under UV irradiation exhibited significant potential in the decolorization of methylene orange (MO) with a percent decolorization of 91.5 % after 20 min. Therefore, it can be concluded that biosynthesized gold nanoparticles as a photocatalyst, anti-bacterial, antifungal, and anti-cancer agents have potential applications in the fields of environment and biology.

Restoring and Enhancing the Potency of Existing Antibiotics against Drug-Resistant Gram-Negative Bacteria through the Development of Potent Small-Molecule Adjuvants.

The rapid and persistent emergence of drug-resistant bacteria poses a looming public health crisis. The possible task of developing new sets of antibiotics to replenish the existing ones is daunting to say the least. Searching for adjuvants that restore or even enhance the potency of existing antibiotics against drug-resistant strains of bacteria represents a practical and cost-effective approach. Herein, we describe the discovery of potent adjuvants that extend the antimicrobial spectrum of existing antibiotics and restore their effectiveness toward drug-resistant strains including mcr-1-expressing strains. From a library of cationic compounds, MD-100, which has a diamidine core structure, was identified as a potent antibiotic adjuvant against Gram-negative bacteria. Further optimization efforts including the synthesis of ∼20 compounds through medicinal chemistry work led to the discovery of a much more potent compound MD-124. MD-124 was shown to sensitize various Gram-negative bacterial species and strains, including multidrug resistant pathogens, toward existing antibiotics with diverse mechanisms of action. We further demonstrated the efficacy of MD-124 in an ex vivo skin infection model and in an in vivo murine systemic infection model using both wild-type and drug-resistant Escherichia coli strains. MD-124 functions through selective permeabilization of the outer membrane of Gram-negative bacteria. Importantly, bacteria exhibited low-resistance frequency toward MD-124. In-depth computational investigations of MD-124 binding to the bacterial outer membrane using equilibrium and steered molecular dynamics simulations revealed key structural features for favorable interactions. The very potent nature of such adjuvants distinguishes them as very useful leads for future drug development in combating bacterial drug resistance.

Activated Mesenchymal Stromal Cell Therapy for Treatment of Multi-Drug Resistant Bacterial Infections in Dogs.

New and creative approaches are required to treat chronic infections caused by increasingly drug-resistant strains of bacteria. One strategy is the use of cellular therapy employing mesenchymal stromal cells (MSC) to kill bacteria directly and to also activate effective host immunity to infection. We demonstrated previously that activated MSC delivered systemically could be used effectively together with antibiotic therapy to clear chronic biofilm infections in rodent models. Therefore, we sought in the current studies to gain new insights into the antimicrobial properties of activated canine MSC and to evaluate their effectiveness as a novel cellular therapy for treatment of naturally-occurring drug resistant infections in dogs. These studies revealed that canine MSC produce and secrete antimicrobial peptides that synergize with most classes of common antibiotics to trigger rapid bactericidal activity. In addition, activated canine MSC migrated more efficiently to inflammatory stimuli, and secreted factors associated with wound healing and fibroblast proliferation and recruitment of activated neutrophils. Macrophages incubated with conditioned medium from activated MSC developed significantly enhanced bactericidal activity. Clinical studies in dogs with chronic multidrug resistant infections treated by repeated i.v. delivery of activated, allogeneic MSC demonstrated significant clinical benefit, including infection clearance and healing of infected tissues. Taken together, the results of these studies provide new insights into antimicrobial activity of canine MSC, and their potential clinical utility for management of chronic, drug-resistant infections.

Controllable Polymerization of N -Substituted β-Alanine N -Thiocarboxyanhydrides for Convenient Synthesis of Functional Poly(β-peptoid)s

Controllable Polymerization of <i>N</i> -Substituted β-Alanine <i>N</i> -Thiocarboxyanhydrides for Convenient Synthesis of Functional Poly(β-peptoid)s

Design and synthesis of new polyamine quinoline antibiotic enhancers to fight resistant gram-negative P. aeruginosa bacteria

The lack of novel drugs in development and the combination of increased incidence of drug-resistant strains of bacteria has created the need for the search for new antimicrobials as well as new original strategies to fight bacterial resistance. In this context, a series of polyamine quinoline derivatives were prepared and biologically evaluated, identifying compounds able to sensitize doxycycline activity towards the Gram-negative bacteria P. aeruginosa. Of note was the identification of antibiotic enhancing analogues whose cytotoxicity ranged from negligible to significant. The mechanism of action of two of the best compounds was studied against P. aeruginosa and S. aureus establishing a different behaviour towards integrity or depolarization of bacterial membranes depending on the structure of the considered polyamine quinoline derivatives.

Antimicrobial effect of radiant catalytic ionization.

The main purpose of micro-organisms elimination from the air and surfaces is to ensure microbiological safety in health care facilities or food production plants. Currently, many disinfection methods are used, both physical, chemical and, increasingly, biological. Scientists seek new solutions with high antimicrobial effectiveness (especially against the drug-resistant strains of bacteria), low production and operating costs, and, above all, the safety of patients and food consumers. The limitation of the methods used so far is primarily the micro-organisms acquire the resistance, mainly to antimicrobial agents. One of the new and alternative methods of disinfection is radiant catalytic ionization (RCI). RCI is an active method of air and surface purification. The technology proved high efficiency against viruses, Gram-positive and -negative bacteria, and fungi, both in the air and on surfaces (planktonic forms and biofilm). RCI has many advantages as well as some minor limitations. This overview summarizes the current knowledge about RCI technology.

Determinant factors for loss to follow-up in drug-resistant tuberculosis patients: the importance of psycho-social and economic aspects

BackgroundDrug-resistant tuberculosis (DR-TB) is the barrier for global TB elimination efforts with a lower treatment success rate. Loss to follow-up (LTFU) in DR-TB is a serious problem, causes mortality and morbidity for patients, and leads to wide spreading of DR-TB to their family and the wider community, as well as wasting health resources. Prevention and management of LTFU is crucial to reduce mortality, prevent further spread of DR-TB, and inhibit the development and transmission of more extensively drug-resistant strains of bacteria. A study about the factors associated with loss to follow-up is needed to develop appropriate strategies to prevent DR-TB patients become loss to follow-up. This study was conducted to identify the factors correlated with loss to follow-up in DR-TB patients, using questionnaires from the point of view of patients.MethodsAn observational study with a cross-sectional design was conducted. Study subjects were all DR-TB patients who have declared as treatment success and loss to follow-up from DR-TB treatment. A structured questionnaire was used to collect information by interviewing the subjects as respondents. Obtained data were analyzed potential factors correlated with loss to follow-up in DR-TB patients.ResultsA total of 280 subjects were included in this study. Sex, working status, income, and body mass index showed a significant difference between treatment success and loss to follow-up DR-TB patients with p-value of 0.013, 0.010, 0.007, and 0.006, respectively. In regression analysis, factors correlated with increased LTFU were negative attitude towards treatment (OR = 1.2; 95% CI = 1.1–1.3), limitation of social support (OR = 1.1; 95% CI = 1.0–1.2), dissatisfaction with health service (OR = 2.1; 95% CI = 1.5–3.0)), and limitation of economic status (OR = 1.1; 95% CI = 1.0–1.2)).ConclusionsMale patients, jobless, non-regular employee, lower income, and underweight BMI were found in higher proportion in LTFU patients. Negative attitude towards treatment, limitation of social support, dissatisfaction with health service, and limitation of economic status are factors correlated with increased LTFU in DR-TB patients. Non-compliance to treatment is complex, we suggest that the involvement and support from the combination of health ministry, labor and employment ministry, and social ministry may help to resolve the complex problems of LTFU in DR-TB patients.

Potent Antiviral and Antimicrobial Polymers as Safe and Effective Disinfectants for the Prevention of Infections.

Disinfection using effective antimicrobials is essential in preventing the spread of infectious diseases. This COVID-19 pandemic has brought the need for effective disinfectants to greater attention due to the fast transmission of SARS-CoV-2. Current active ingredients in disinfectants are small molecules that microorganisms can develop resistance against after repeated long-term use and may penetrate the skin, causing harmful side-effects. To this end, a series of membrane-disrupting polyionenes that contain quaternary ammoniums and varying hydrophobic components is synthesized. They are effective against bacteria and fungi. They are also fast acting against clinically isolated drug resistant strains of bacteria. Formulating them with thickeners and nonionic surfactants do not affect their killing efficiency. These polyionenes are also effective in preventing infections caused by nonenveloped and enveloped viruses. Their effectiveness against mouse coronavirus (i.e., mouse hepatitis virus-MHV) depends on their hydrophobicity. The polyionenes with optimal compositions inactivates MHV completely in 30 s. More importantly, the polyionenes are effective in inhibiting SARS-CoV-2 by >99.999%within 30 s. While they are effective against the microorganisms, they do not cause damage to the skin and have a high oral lethal dose. Overall, these polyionenes are promising active ingredients for disinfection and prevention of viral and microbial infections.

Can Immobilized Artificial Membrane Chromatography Support the Characterization of Antimicrobial Peptide Origin Derivatives?

The emergence and spread of multiple drug-resistant bacteria strains caused the development of new antibiotics to be one of the most important challenges of medicinal chemistry. Despite many efforts, the commercial availability of peptide-based antimicrobials is still limited. The presented study aims to explain that immobilized artificial membrane chromatography can support the characterization of antimicrobial peptides. Consequently, the chromatographic experiments of three groups of related peptide substances: (i) short cationic lipopeptides, (ii) citropin analogs, and (iii) conjugates of ciprofloxacin and levofloxacin, with a cell-penetrating peptide were discussed. In light of the discussion of the mechanisms of action of these compounds, the obtained results were interpreted.

Project to Reduce Cases of Drug-Resistant Strain Colonization in the Intensive Care Unit Using a Chlorhexidine Gluconate Bath

Drug-resistant strains of bacteria are associated with severe consequences such as bacteremia, shock, and death, and increase hospital stay durations and medical health expenses. Therefore, reducing the spread of drug-resistant strains is a priority concern. This project was developed to reduce the number of colonization cases of drug-resistant strains and subsequently increase the quality of care provided in our intensive care unit. In this project, a chlorhexidine gluconate (CHG) bath standard protocol and CHG bath skill checklist were established, education and training courses were planned, a regular bed curtain replacement schedule and sink cleaning protocols were implemented, and regular audits were conducted. Immediately following project implementation (October - December 2018), the average monthly cases of Vancomycin-resistant enterococci colonization decreased from 6.08 to 4.33, and the average monthly cases of multi-drug resistant Acinebacter baumannii colonization decreased from 4.08 to 1.33. Furthermore, between January and July 2019, the average monthly cases of colonization for the abovementioned bacteria numbered 4 and 0.86, respectively, which met the level of reduction targeted in this project. The results of this project indicate that implementing CHG bed baths is effective in reducing the incidence of drug resistant strain colonization and rate of related infections in patients. CHG bed baths should be applied clinically to improve the quality of intensive care.

Protective Efficacy of Novel Oral Biofilm Vaccines against Lactococcus garvieae Infection in Mullet, Mugil cephalus.

Lactococcus garvieae (L. garvieae) is an important pathogen that causes enormous economic losses in both marine and freshwater aquaculture. At present, antibiotics are the only option for farmers to reduce the losses caused by L. garvieae. However, the usage of antibiotics leads to environmental pollution and the production of drug-resistant strains of bacteria. Therefore, vaccination is preferred as an alternative method to prevent infectious diseases. In this study, we describe an effective approach to the production of an oral biofilm vaccine, using bacteria grown on chitosan particles to form biofilms, and thus providing an inactive pathogen that enhances the immune response in fish. We observed the formation of a biofilm on chitosan particles and administered the novel oral biofilm vaccine to fish. We analyzed the immune responses, including antibody production, phagocytic ability, albumin/globulin ratio and immune-related genes, of vaccinated and control groups of black mullet. Our results show that the phagocytic ability of the biofilm vaccine group was 84%, which is significantly higher than that of the control group, and the antibody production in this group was significantly higher compared with the other group. The mRNA expression levels of immune-related genes (TLR2, IL-1β, TNF-α) were significantly upregulated in the spleen after vaccination. In challenge experiments, the relative percent survival (RPS) was 77% in the biofilm vaccine group, 18% in the whole-cell vaccine group, and 0% in the chitosan particle group at 32 days post-vaccination. In addition, we also found that the relative percent survival (RPS) at 1 day post-vaccination was 74% in the biofilm vaccine group, 42% in the whole-cell vaccine group, and 26% in the chitosan particle group. In both long-term and short-term challenge experiments, the viability of the biofilm vaccine group was significantly higher than that of the whole-cell, chitosan particle and PBS groups. We conclude that based on its protective effect, the L. garvieae biofilm vaccine is better than the whole-cell vaccine when challenged several weeks after vaccination. In addition, the biofilm vaccine also has a greater protective effect than the whole-cell vaccine when challenged immediately after vaccination. Therefore, the biofilm vaccine might represent a novel method for the prevention and treatment of L. garvieae infection.

Antileishmanial and antibacterial activities of biologically synthesized silver nanoparticles using Alcea rosea extract (AR-AgNPs)

Recent developments in nanotechnology lead to draw scientist's interest in green synthesis nanoparticles because of their importance in all fields of sciences. This paper is an overview of Ag nanoparticles biosynthesis (AgNPs) by aerial part of Alcea rosea extract. Synthesis procedures were described, with no stabilizers or surfactants. The synthesized AR@AgNPs were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), and UV-Vis analysis. The UV-Vis spectrum of AR@AgNPs shown a characteristic surface plasmon resonance (SPR) peak at 425 nm. Scanning electron microscope revealed spherical shaped with a diameter range of 10-30 nm. Energy dispersive X-ray spectroscopy analysis demonstrated the peak in silver region confirming presence of elemental silver. Evaluation of the antibacterial and antileishmanial activity of biosynthesized silver nanoparticles was performed. AR@AgNPs exhibit effective antibacterial activity against seven ATCC strains of bacteria and eight strains of drug-resistant bacteria. Also, their activity against leishmaniasis was studied on both promastigotes and amastigotes.