Antibacterial and antibiofilm potentials of vancomycin-loaded niosomal drug delivery system against methicillin-resistant Staphylococcus aureus (MRSA) infections.

The threat of methicillin-resistant Staphylococcus aureus (MRSA) is increasing worldwide, making it significantly necessary to discover a novel way of dealing with related infections. The quick spread of MRSA isolates among infected individuals has heightened public health concerns and significantly limited treatment options. Vancomycin (VAN) can be applied to treat severe MRSA infections, and the indiscriminate administration of this antimicrobial agent has caused several concerns in medical settings. Owing to several advantageous characteristics, a niosomal drug delivery system may increase the potential of loaded antimicrobial agents. This work aims to examine the antibacterial and anti-biofilm properties of VAN-niosome against MRSA clinical isolates with emphasis on cytotoxicity and stability studies. Furthermore, we aim to suggest an effective approach against MRSA infections by investigating the inhibitory effect of formulated niosome on the expression of the biofilm-associated gene (icaR). The thin-film hydration approach was used to prepare the niosome (Tween 60, Span 60, and cholesterol), and field emission scanning electron microscopy (FE-SEM), an in vitro drug release, dynamic light scattering (DLS), and entrapment efficiency (EE%) were used to investigate the physicochemical properties. The physical stability of VAN-niosome, including hydrodynamic size, polydispersity index (PDI), and EE%, was analyzed for a 30-day storage time at 4 °C and 25 °C. In addition, the human foreskin fibroblast (HFF) cell line was used to evaluate the cytotoxic effect of synthesized niosome. Moreover, minimum inhibitory and bactericidal concentrations (MICs/MBCs) were applied to assess the antibacterial properties of niosomal VAN formulation. Also, the antibiofilm potential of VAN-niosome was investigated by microtiter plate (MTP) and real-time PCR methods. The FE-SEM result revealed that synthesized VAN-niosome had a spherical morphology. The hydrodynamic size and PDI of VAN-niosome reported by the DLS method were 201.2 nm and 0.301, respectively. Also, the surface zeta charge of the prepared niosome was - 35.4 mV, and the EE% ranged between 58.9 and 62.5%. Moreover, in vitro release study revealed a sustained-release profile for synthesized niosomal formulation. Our study showed that VAN-niosome had acceptable stability during a 30-day storage time. Additionally, the VAN-niosome had stronger antibacterial and anti-biofilm properties against MRSA clinical isolates compared with free VAN. In conclusion, the result of our study demonstrated that niosomal VAN could be promising as a successful drug delivery system due to sustained drug release, negligible toxicity, and high encapsulation capacity. Also, the antibacterial and anti-biofilm studies showed the high capacity of VAN-niosome against MRSA clinical isolates. Furthermore, the results of real-time PCR exhibited that VAN-niosome could be proposed as a powerful strategy against MRSA biofilm via down-regulation of icaR gene expression.

Surface modified niosomal quercetin with cationic lipid: an appropriate drug delivery system against Pseudomonas aeruginosa Infections.

The Increase in infections caused by resistant strains of Pseudomonas aeruginosa poses a formidable challenge to global healthcare systems. P. aeruginosa is capable of causing severe human infections across diverse anatomical sites, presenting considerable therapeutic obstacles due to its heightened drug resistance. Niosomal drug delivery systems offer enhanced pharmaceutical potential for loaded contents due to their desirable properties, mainly providing a controlled-release profile. This study aimed to formulate an optimized niosomal drug delivery system incorporating stearylamine (SA) to augment the anti-bacterial and anti-biofilm activities of quercetin (QCT) against both standard and clinical strains of P. aeruginosa. QCT-loaded niosome (QCT-niosome) and QCT-loaded SA- niosome (QCT-SA- niosome) were synthesized by the thin-film hydration technique, and their physicochemical characteristics were evaluated by field emission scanning electron microscopy (FE-SEM), zeta potential measurement, entrapment efficacy (EE%), and in vitro release profile. The anti-P. aeruginosa activity of synthesized niosomes was assessed using minimum inhibitory and bactericidal concentrations (MICs/MBCs) and compared with free QCT. Additionally, the minimum biofilm inhibitory and eradication concentrations (MBICs/MBECs) were carried out to analyze the ability of QCT-niosome and QCT-SA-niosome against P. aeruginosa biofilms. Furthermore, the cytotoxicity assay was conducted on the L929 mouse fibroblasts cell line to evaluate the biocompatibility of the formulated niosomes. FE-SEM analysis revealed that both synthesized niosomal formulations exhibited spherical morphology with different sizes (57.4 nm for QCT-niosome and 178.9 nm for QCT-SA-niosome). The EE% for cationic and standard niosomal formulations was reported at 75.9% and 59.6%, respectively. Both formulations showed an in vitro sustained-release profile, and QCT-SA-niosome exhibited greater stability during a 4-month storage time compared to QCT-niosome. Microbial experiments indicated that both prepared formulations had higher anti-bacterial and anti-biofilm activities than free QCT. Also, the QCT-SA-niosome exhibited greater reductions in MIC, MBC, MBIC, and MBEC values compared to the QCT-niosome at equivalent concentrations. This study supports the potential of QCT-niosome and QCT-SA-niosome as effective agents against P. aeruginosa infections, manifesting significant anti-bacterial and anti-biofilm efficacy alongside biocompatibility with L929 cell lines. Furthermore, our results suggest that optimized QCT-niosome with cationic lipids could efficiently target P. aeruginosa cells with negligible cytotoxic effect.

Novel therapeutic strategy for obesity through the gut microbiota-brain axis: A review article.

Background: The interaction between commensal bacteria and the host is essential for health and the gut microbiota-brain axis plays a vital role in this regard. Obesity as a medical problem not only affect the health of the individuals, but also the economic and social aspects of communities. The presence of any dysbiosis in the composition of the gut microbiota disrupts in the gut microbiota-brain axis, which in turn leads to an increase in appetite and then obesity. Because common treatments for obesity have several drawbacks, the use of microbiota-based therapy in addition to treatment and prevention of obesity can have other numerous benefits for the individual. In this review, we intend to investigate the relationship between obesity and the gut microbiota-brain axis as well as novel treatment strategies based on this axis with an emphasis on gut microbiota.

Co-delivery of doxycycline and rifampicin using CdTe-labeled poly (lactic-co-glycolic) acid for treatment of Brucella melitensis infection.

Brucellosis poses a significant challenge in the medical field as a systemic infection with a propensity for relapse. This study presented a novel approach to brucellosis treatment, enhancing the efficacy of doxycycline and rifampicin through the use of poly (lactic-co-glycolic) acid coupled with cadmium-telluride quantum dots (Dox-Rif-PLGA@CdTe). The double emulsion solvent evaporation method was employed to prepare Dox-Rif-PLGA@CdTe. The study scrutinized the physicochemical attributes of these nanoparticles. The impact of antibiotic-loaded nanoparticles on Brucella melitensis was evaluated through well diffusion, minimum inhibitory concentration (MIC), and cell culture. The chemical analysis results demonstrated a possibility of chemical reactions occurring among the constituents of nanoparticles. Assessments using the well diffusion and MIC methods indicated that the impact of free drugs and nanoparticles on bacteria was equivalent. However, the drug-loaded nanoparticles significantly decreased the colony-forming units (CFUs) within the cell lines compared to free drugs. In conclusion, the synthesis of nanoparticles adhered to environmentally friendly practices and demonstrated safety. The sustained drug release over 100 h facilitated drug accumulation at the bacterial site, resulting in a heightened therapeutic effect on B. melitensis and improved outcomes in brucellosis treatment. The application of these synthesized nanodrugs exhibited promising therapeutic potential.

Staphopain mediated virulence and antibiotic resistance alteration in co-infection of Staphylococcus aureus and Pseudomonas aeruginosa: an animal model.

Polymicrobial communities lead to worsen the wound infections, due to mixed biofilms, increased antibiotic resistance, and altered virulence production. Promising approaches, including enzymes, may overcome the complicated condition of polymicrobial infections. Therefore, this study aimed to investigate Staphopain A-mediated virulence and resistance alteration in an animal model of Staphylococcus aureus and Pseudomonas aeruginosa co-infection. S. aureus and P. aeruginosa were co-cultured on the L-929 cell line and wound infection in an animal model. Then, recombinant staphopain A was purified and used to treat mono- and co-infections. Following the treatment, changes in virulence factors and resistance were investigated through phenotypic methods and RT-PCR. Staphopain A resulted in a notable reduction in the viability of S. aureus and P. aeruginosa. The biofilm formed in the wound infection in both animal model and cell culture was disrupted remarkably. Moreover, the biofilm-encoding genes, quorum sensing regulating genes, and virulence factors (hemolysin and pyocyanin) controlled by QS were down-regulated in both microorganisms. Furthermore, the resistance to vancomycin and doripenem decreased following treatment with staphopain A. According to this study, staphopain A might promote wound healing and cure co-infection. It seems to be a promising agent to combine with antibiotics to overcome hard-to-cure infections.

Solid lipid nanoparticles and their application in the treatment of bacterial infectious diseases.

Nano pharmacology is considered an effective, safe, and applicable approach for drug delivery applications. Solid lipid nanoparticle (SLNs) colloids contain biocompatible lipids which are capable of encapsulating and maintaining hydrophilic or hydrophobic drugs in the solid matrix followed by releasing the drug in a sustained manner in the target site. SLNs have more promising potential than other drug delivery systems for various purposes. Nowadays, the SLNs are used as a carrier for antibiotics, chemotherapeutic drugs, nucleic acids, herbal compounds, etc. The SLNs have been widely applied in biomedicine because of their non-toxicity, biocompatibility, and simple production procedures. In this review, the complications related to the optimization, preparation process, routes of transplantation, uptake and delivery system, and release of the loaded drug along with the advantages of SLNs as therapeutic agents were discussed.

The healing effect of Pseudomonas Quinolone Signal (PQS) with co-infection of Staphylococcus aureus and Pseudomonas aeruginosa: A preclinical animal co-infection model.

BACKGROUND: Because of the rise in antibiotic resistance and the control of pathogenicity, polymicrobial bacterial biofilms exacerbate wound infections. Since bacterial quorum sensing (QS) signals can dysregulate biofilm development, they are interesting therapeutic treatments. In this study, Pseudomonas Quinolone Signal (PQS) was used to treat an animal model of a wound that had both Staphylococcus aureus and Pseudomonas aeruginosa co-infection. METHODS: S. aureus and P. aeruginosa mono- and co-infection models were developed in vitro on the L-929 cell line and in an animal model of wound infection. Moreover, PQS was extracted and purified using liquid chromatography. Then, the mono- and co-infection models were treated by PQS in vitro and in vivo. RT-PCR analysis was used to look into changes in biofilm, QS, tissue regeneration, and apoptosis genes after the treatment. RESULTS: PQS significantly disrupted established biofilm up to 90% in both in vitro and in vivo models. Moreover, a 93% reduction in the viability of S. aureus and P. aeruginosa was detected during the 10 days of treatment in comparison to control groups. In addition, the biofilm-encoding and QS-regulating genes were down-regulated to 75% in both microorganisms. Also, fewer epithelial cells died when treated with PQS compared to control groups in both mono- and co-infection groups. CONCLUSION: According to this study, PQS may facilitate wound healing by stimulating the immune system and reducing apoptosis. It seems to be a potential medication to use in conjunction with antibiotics to treat infections that are difficult to treat.

The destruction of mucosal barriers, epithelial remodeling, and impaired mucociliary clearance: possible pathogenic mechanisms of Pseudomonas aeruginosa and Staphylococcus aureus in chronic rhinosinusitis.

Chronic rhinosinusitis (CRS) is a pathological condition characterized by persistent inflammation in the upper respiratory tract and paranasal sinuses. The epithelium serves as the first line of defense against potential threats and protects the nasal mucosa. The fundamental mechanical barrier is formed by the cell-cell contact and mucociliary clearance (MCC) systems. The physical-mechanical barrier is comprised of many cellular structures, including adhesion junctions and tight junctions (TJs). To this end, different factors, such as the dysfunction of MCC, destruction of epithelial barriers, and tissue remodeling, are related to the onset and development of CRS. Recently published studies reported the critical role of different microorganisms, such as Staphylococcus aureus and Pseudomonas aeruginosa, in the induction of the mentioned factors. Bacteria could result in diminished ciliary stimulation capacity, and enhance the chance of CRS by reducing basal ciliary beat frequency. Additionally, bacterial exoproteins have been demonstrated to disrupt the epithelial barrier and induce downregulation of transmembrane proteins such as occludin, claudin, and tricellulin. Moreover, bacteria exert an influence on TJ proteins, leading to an increase in the permeability of polarized epithelial cells. Noteworthy, it is evident that the activation of TLR2 by staphylococcal enterotoxin can potentially undermine the structural integrity of TJs and the epithelial barrier through the induction of pro-inflammatory cytokines. The purpose of this article is an attempt to investigate the possible role of the most important microorganisms associated with CRS and their pathogenic mechanisms against mucosal surfaces and epithelial barriers in the paranasal sinuses. Video Abstract.

Effect of poly (lactic-co-glycolic acid) polymer nanoparticles loaded with vancomycin against Staphylococcus aureus biofilm.

Staphylococcus aureus is a unique challenge for the healthcare system because it can form biofilms, is resistant to the host's immune system, and is resistant to numerous antimicrobial therapies. The aim of this study was to investigate the effect of poly (lactic-co-glycolic acid) (PLGA) polymer nanoparticles loaded with vancomycin and conjugated with lysostaphin (PLGA-VAN-LYS) on inhibiting S. aureus biofilm formation. Nano drug carriers were produced using the double emulsion evaporation process. we examined the physicochemical characteristics of the nanoparticles, including particle size, polydispersity index (PDI), zeta potential, drug loading (DL), entrapment efficiency (EE), Lysostaphin conjugation efficiency (LCE), and shape. The effect of the nano drug carriers on S. aureus strains was evaluated by determining the minimum inhibitory concentration (MIC), conducting biofilm formation inhibition studies, and performing agar well diffusion tests. The average size, PDI, zeta potential, DL, EE, and LCE of PLGA-VAN-LYS were 320.5 ± 35 nm, 0.270 ± 0.012, -19.5 ± 1.3 mV, 16.75 ± 2.5%, 94.62 ± 2.6%, and 37% respectively. Both the agar well diffusion and MIC tests did not show a distinction between vancomycin and the nano drug carriers after 72 h. However, the results of the biofilm analysis demonstrated that the nano drug carrier had a stronger inhibitory effect on biofilm formation compared to the free drug. The use of this technology for treating hospital infections caused by the Staphylococcus bacteria may have favorable effects on staphylococcal infections, considering the efficacy of the nano medicine carrier developed in this study.

Co-delivery of streptomycin and hydroxychloroquine by labeled solid lipid nanoparticles to treat brucellosis: an animal study.

Can brucellosis-related biochemical and immunological parameters be used as diagnostic and treatment indicators? The goal of this project was to look at biochemical parameters, trace elements, and inflammatory factors in the acute and chronic stages of brucellosis after treatment with streptomycin and hydroxychloroquine-loaded solid lipid nanoparticles (STR-HCQ-SLN). The double emulsion method was used for the synthesis of nanoparticles. Serum levels of trace elements, vitamin D, CRP, and biochemical parameters were measured in rats involved in brucellosis. The therapeutic effect of STR-HCQ-SLN was compared with that of free drugs. In both healthy and infected rats, serum concentrations of copper, zinc, iron, magnesium, potassium, and biochemical parameters of the liver were significantly different. By altering the serum levels of the aforementioned factors, treatment with STR-HCQ-SLN had a positive therapeutic effect on chronic brucellosis. Vitamin D levels declined (46.4%) and CRP levels rose (from 7.5 mg to less than 1 mg) throughout the acute and chronic stages of brucellosis. This study showed that by comparing the biochemical parameters and the levels of trace elements in the serum of healthy and diseased mice in the acute and chronic stages of brucellosis, it is possible to get help from other routine methods for diagnosis.

Multidrug-Resistant Pathogens in Burn Wound, Prevention, Diagnosis, and Therapeutic Approaches (Conventional Antimicrobials and Nanoparticles).

Multidrug-resistant pathogens are one of the common causes of death in burn patients and have a high risk of nosocomial infections, especially pneumonia, urinary tract infections, and cellulitis. The role of prolonged hospitalization and empirical antibiotics administration in developing multidrug-resistant pathogens is undeniable. In the early days of admitting burn patients, Gram-positive bacteria were the dominant isolates with a more sensitive antibiotic pattern. However, the emergence of Gram-negative bacteria that are more resistant later occurs. Trustworthy guideline administration in burn wards is one of the strategies to prevent multidrug-resistant pathogens. Also, a multidisciplinary therapeutic approach is an effective way to avoid antibiotic resistance that involves infectious disease specialists, pharmacists, and burn surgeons. However, the emerging resistance to conventional antimicrobial approaches (such as systemic antibiotic exposure, traditional wound dressing, and topical antibiotic ointments) among burn patients has challenged the treatment of multidrug-resistant infections, and using nanoparticles is a suitable alternative. In this review article, we will discuss different aspects of multidrug-resistant pathogens in burn wounds, emphasizing the full role of these pathogens in burn wounds and discussing the application of nanotechnology in dealing with them. Also, some advances in various types of nanomaterials, including metallic nanoparticles, liposomes, hydrogels, carbon quantum dots, and solid lipid nanoparticles in burn wound healing, will be explained.

Association of qnr Genes and OqxAB Efflux Pump in Fluoroquinolone-Resistant Klebsiella pneumoniae Strains.

Background: The aim of this study was to investigate the frequency and relationship between plasmid-mediated quinolone resistance genes and OqxAB pump genes, as well as the genetic linkage in K. pneumoniae strains isolated from Hamadan hospitals in the west of Iran. Materials and Methods: In this study, 100 K. pneumoniae clinical strains were isolated from clinical samples of inpatients at Hamadan Hospital in 2021. The antimicrobial susceptibility testing was performed using the disk diffusion method. The frequencies of genes encoding OqxAB efflux pumps and qnr were investigated by PCR. Molecular typing of qnr-positive K. pneumoniae isolates was assessed by ERIC-PCR. Results: Antibiotic susceptibility testing showed high resistance (>80%) to fluoroquinolones. The gene encoding the OqxAB efflux pump was detected in more than 90% of K. pneumomiae strains. All K. pneumoniae isolates were negative for qnrA, and 20% and 9% of the isolates were positive for qnrB and qnrS, respectively. The genes encoding oqxA and oqxB were detected in 96% of qnr-positive strains. A qnrB + /qnrS + profile was observed in 16% of qnr-positive K. pneumoniae strains. Ciprofloxacin MIC ≥ 256 µg/ml was detected in 20% of qnr-positive strains. Genetic association analysis by ERIC-PCR revealed genetic diversity among 25 different qnr-positive strains of K. pneumonia. Conclusion: However, no significant correlation was found between the qnr and the OqxAB efflux pump genes in this study. The high rate of fluoroquinolone resistance and determinants of antibiotic resistance among diverse K. pneumoniae strains increase the risk of fluoroquinolone-resistance transmission by K. pneumoniae strains in hospitals.

Antimicrobial and cytotoxic properties of calcium-enriched mixture cement, Iranian propolis, and propolis with herbal extracts in primary dental pulp stem cells.

Objectives: In this study, natural substances were introduced as primary dental pulp caps for use in pulp therapy, and the antimicrobial and cytotoxic properties of these substances were investigated. Materials and Methods: In this in vitro study, the antimicrobial properties of calcium-enriched mixture (CEM) cement, propolis, and propolis individually combined with the extracts of several medicinal plants were investigated against Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Then, the cytotoxicity of each substance or mixture against pulp stem cells extracted from 30 primary healthy teeth was evaluated at 4 concentrations. Data were gathered via observation, and optical density values were obtained using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) test and recorded. SPSS software version 23 was used to analyze the data. Data were evaluated using 2-way analysis of variance and the Tukey test. Results: Regarding antimicrobial properties, thyme alone and thyme + propolis had the lowest minimum inhibitory concentrations (MICs) against the growth of S. aureus, E. coli, and P. aeruginosa bacteria. For E. faecalis, thyme + propolis had the lowest MIC, followed by thyme alone. At 24 and 72 hours, thyme + propolis, CEM cement, and propolis had the greatest bioviability in the primary dental pulp stem cells, and lavender + propolis had the lowest bioviability. Conclusions: Of the studied materials, thyme + propolis showed the best results in the measures of practical performance as a dental pulp cap.

Relationship of OqxAB efflux pump to antibiotic resistance, mainly fluoroquinolones in Klebsiella pneumoniae, isolated from hospitalized patients.

Objectives: This research was designed to study the prevalence of OqxAB efflux pump genes and also to investigate the relationship between efflux pump and resistance to antibiotics, especially to fluoroquinolones, evaluate the expression levels of OqxAB genes, and molecular typing of Klebsiella pneumoniae isolated from hospitalized patients in Hamadan hospitals, west of Iran. Materials and Methods: In a cross-sectional study, 100 clinical strains of K. pneumoniae were isolated from hospitalized patients in three major teaching hospitals from January to June 2021. The antibiotic susceptibility of isolates was evaluated by the disk-diffusion agar method. The frequency of genes encoding oqxA and oqxB of efflux pump genes was investigated by PCR, and the expression of the oqxA efflux pump gene was investigated by the Real-time PCR method. The genetic relationship of K. pneumoniae isolates was analyzed by the Enterobacterial Repetitive Intergenic Consensus (ERIC)-PCR technique. Results: According to our results, the multi-drug resistance phenotype (MDR) in 65% and high prevalence resistance to ciprofloxacin in 89% of K. pneumoniae isolates was detected. The higher prevalence of oqxA (95%) and oqxB (98%) was also detected. There was a significant relationship between ciprofloxacin resistance and the oqxB gene as well as between ceftriaxone and chloramphenicol resistance and the oqxA gene. The expression of the oqxA gene was higher in ciprofloxacin-resistant isolates. Conclusion: The results of this study suggest a potential reservoir for the spread of OqxAB genes among hospital-acquired bacteria. Infection control strategies should be used prudently to reduce the spread of resistant strains of K. pneumoniae in hospitals.

Graphene-Based Materials for Inhibition of Wound Infection and Accelerating Wound Healing.

Bacterial infection of the wound could potentially cause serious complications and an enormous medical and financial cost to the rapid emergence of drug-resistant bacteria. Nanomaterials are an emerging technology, that has been researched as possible antimicrobial nanomaterials for the inhibition of wound infection and enhancement of wound healing. Graphene is 2-dimensional (2D) sheet of sp2 carbon atoms in a honeycomb structure. It has superior properties, strength, conductivity, antimicrobial, and molecular carrier abilities. Graphene and its derivatives, Graphene oxide (GO) and reduced GO (rGO), have antibacterial activity and could damage bacterial morphology and lead to the leakage of intracellular substances. Besides, for wound infection management, Graphene-platforms could be functionalized by different antibacterial agents such as metal-nanoparticles, natural compounds, and antibiotics. The Graphene structure can absorb near-infrared wavelengths, allowing it to be used as antimicrobial photodynamic therapy. Therefore, Graphene-based material could be used to inhibit pathogens that cause serious skin infections and destroy their biofilm community, which is one of the biggest challenges in treating wound infection. Due to its agglomerated structure, GO hydrogel could entrap and stack the bacteria; thus, it prevents their initial attachment and biofilm formation. The sharp edges of GO could destroy the extracellular polymeric substance surrounding the biofilm and ruin the biofilm biomass structure. As well as, Chitosan and different natural and synthetic polymers such as collagen and polyvinyl alcohol (PVA) also have attracted a great deal of attention for use with GO as wound dressing material. To this end, multi-functional polymers based on Graphene and blends of synthetic and natural polymers can be considered valid non-antibiotic compounds useful against wound infection and improvement of wound healing. Finally, the global wound care market size was valued at USD 20.8 billion in 2022 and is expected to expand at a compound annual growth rate (CAGR) of 5.4% from 2022 to 2027 (USD 27.2 billion). This will encourage academic as well as pharmaceutical and medical device industries to investigate any new materials such as graphene and its derivatives for the treatment of wound healing.

Evaluation of Nano TiO2 Modified Orthodontic Composite Effects on S. mutans Population and Enamel Demineralization in Fixed Orthodontic Patients; a Split Mouth Randomized Controlled Clinical Trial.

The high incidence of demineralization around orthodontic brackets has led to the development of preventive measures. Incorporation of antibacterial or remineralizing agents into orthodontic adhesives is an attractive method. This single-center, split-mouth, randomized controlled clinical trial was conducted to assess the effect of a modified composite containing TiO2 nanoparticles on the Streptococcus mutans population and to prevent demineralization around orthodontic brackets. Each participant was assigned a random sequence (AB or BA). During the bonding session, the control lateral incisor was bonded with a conventional composite and the contralateral incisor was bonded with a composite containing nano TiO2 particles (1%weight). The eligibility criteria included the presence of S. mutans in the dental plaque and absence of active caries, fractures or cracks. The S. mutans count in the dental plaque immediately around the brackets was evaluated at baseline and 1, 3, and 6 months after bonding. The specificity of the colonies was determined by PCR. The DIAGNOdent score was assessed at baseline and re-assessed every month up to the sixth month. Salivary samples were collected at T0, T1, and T3 to assess the amount of Ti released from the composite. The cytotoxicity of the modified composites was evaluated using an MTT assay. Participants, examiners, and data analyzers were blinded to the test and intervention groups. Forty-two patients ranging from 12 to 25 years were enrolled in this study. The amount of Ti released into saliva was insignificant and far below the toxic level. There was no significant difference between the S. mutans counts of the studied tooth S. mutans counts at any time point evaluated. DIAGNOdent scores on both sides increased significantly after the first month. However, this increase was higher on the test side (p < 0.001), and a significant difference of 2.6 scores remained throughout the study period. No severe adverse events were observed. Orthodontic composites containing TiO2 nanoparticles may prevent demineralization induced around brackets during orthodontic treatment. However, the antibacterial effects were not statistically significant.Registration: The protocol was registered with the IRCT.ir (IRCT20140215016582N6).

Use of the quantum dot-labeled solid lipid nanoparticles for delivery of streptomycin and hydroxychloroquine: A new therapeutic approach for treatment of intracellular Brucella abortus infection.

Brucellosis is considered one of the most important infectious diseases affecting any tissue and organ in the human body. Due to the intracellular pathogenesis of Brucella species, the use of conventional antibiotics for managing chronic brucellosis has several limitations. Therefore, the study focused on the use of solid lipid nanoparticles (SLN) to deliver streptomycin (STR) for intracellular infection, with or without the combination of hydroxychloroquine (HCQ) to evaluate if there might be a boost in the antibiotic effect when using the STR or STR-NPs alone. We used the double emulsion technique to synthesize Nano drug carriers; afterward, the physicochemical characteristics of synthesized Nano drug carriers were determined. The in vitro antibacterial activity of free drugs and Nano drug carriers were evaluated using well diffusion, broth microdilution assays (BMD), and murine macrophage-like cells cell line J774A.1. Additionally, acute and chronic phases of brucellosis were inducted into Wistar rats, and healing capacity of Nano drug carriers on liver and spleen tissues was compared with free drugs. The zeta potential of nanoparticles, means of size, Polydispersity Index (PDI), drugs loading, and encapsulation efficiency were 15.2 mV, 312.5 ± 26 nm, 0.433 ± 0.09, 16.6% and 89.5%, respectively. Well diffusion and BMD methods did not show a significantly differ between free drugs and nano drug carriers. However, the Nano drug carriers remarkably decreased the number of bacteria in the cell line compared to the free drugs. STR/HCQ-SLN enhanced the healing processes of the liver and spleen after brucellosis induction. STR/HCQ-SLN showed better inhibitory effects against the chronic phase of B. abortus infection in comparison to the STR-SLN, but this difference was not statistically significant. Using nanoplatforms to enhance conventional anti-brucellosis agents is promising, green and safe. Due to the continuous release of drugs, drugs increase their accumulation at the site of infection, causing a more significant effect on the chronic and acute phases of brucellosis.

Inhibitory activities of vitamins K2 against clinical isolates of quinolone-resistant and methicillin-resistant Staphylococcus aureus (QR-MRSA) with different multi-locus sequence types (MLST), SCCmec, and spa types.

BACKGROUND: The inhibitory activities of vitamins K2 against clinical isolates of quinolone-resistant and methicillin-resistant Staphylococcus aureus (QR-MRSA) are unclear. The main aim is to better understand of inhibitory activities of vitamins K2, multi-locus sequence typing (MLST), SCCmec, and spa typing in clinical isolates of QR-MRSA on those mutation and gene expressions. MATERIALS AND METHODS: After collecting S. aureus clinical isolates and detecting QR-MRSA, the genes encoding norA, grlA, grlB, gyrA, and gyrB were sequenced. After treating isolates by vitamin K2, isolates were prepared to measure norA, grlA, grlB, gyrA, and gyrB gene expression. The quantitative-real-time PCR was used to measure the expression of efflux pump genes. RESULTS: QR-MRSA, MDR, and XDR strains were reported in 59.4%, 73.9%, and 37.6% of isolates, respectability. SCCmecIV (36.5%) and SCCmecV (26.8%) had the highest frequency. Thirty-nine spa types were identified, t021, t044, and t267 types most prevalent in QR-MRSA isolates. ST22 and ST30 dominated the invasive, drug-resistant isolates and QR-MRSA. In 24 h incubated isolates, the most noticeable change of gene expression with vitamin K2 was that the norA, gyrA, and grlB genes were highly repressed. However, the down-regulation of grlA at 24 h after being treated by vitamin K2 was more than another gene. Further, a significant decrease was observed in QR-MRSA-treated isolates compared to un-treated isolates. In other words, norA, grlA, grlB, gyrA, and gyrB genes were less suppressed by QR-MRSA (p ≤ 0.01, p ≤ 0.05). CONCLUSION: Vitamin K2 has significant inhibitory effects on the genes responsible for resistance to fluoroquinolone antibiotics. However, a subminimum inhibitory concentration (sub-MIC) level of vitamin K2 was delayed but did not completely inhibit norA, grlA, grlB, gyrA, and gyrB genes in MRSA strains.

The issue beyond resistance: Methicillin-resistant Staphylococcus epidermidis biofilm formation is induced by subinhibitory concentrations of cloxacillin, cefazolin, and clindamycin.

Staphylococcus epidermis is one of the most frequent causes of device-associated infections due to biofilm formation. Current reports noted that subinhibitory concentrations of antibiotics induce biofilm production in some bacteria. Accordingly, we evaluated the effect of exposure of different subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin on the biofilm formation of methicillin-resistant S. epidermidis (MRSE). Antimicrobial susceptibility testing and minimum inhibitory/bactericidal concentration of antimicrobial agents were determined. MRSE isolates were selected, and their biofilm formation ability was evaluated. The effect of subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin, antibiotics selected among common choices in the clinic, on MRSE biofilm formation was determined by the microtitre method. Besides, the effect of subinhibitory concentrations of cloxacillin, cefazolin, clindamycin, and vancomycin on the expression of the biofilm-associated genes icaA and atlE was evaluated by Reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR). Antimicrobial susceptibility patterns of MRSE strains showed a high level of resistance as follows: 80%, 53.3%, 33.3%, 33.3%, and 26.6%, for erythromycin, trimethoprim-sulfamethoxazole, tetracycline, clindamycin, and gentamicin, respectively. Besides, 73.3% of S. epidermidis strains were Multidrug-resistant (MDR). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values were in the range of 0.5 to512 µg/mL and 1 to1024 µg/mL for cloxacillin, 0.125 to256 µg/mL and 1 to512 µg/mL for cefazolin, 0.125 to64 µg/mL and 4 to>1024 µg/mL for clindamycin, and 2 to32 µg/mL and 4 to32 µg/mL for vancomycin, respectively. The findings showed that subinhibitory concentrations of cloxacillin, cefazolin, and clindamycin induce biofilm production in MRSE strains. In particular, the OD values of strains were in the range of 0.09-0.95, 0.05-0.86, and 0.06-1 toward cloxacillin, cefazolin, and clindamycin, respectively. On the other hand, exposure to subinhibitory vancomycin concentrations did not increase the biofilm formation in MRSE strains. The findings also demonstrated that sub-MIC of antibiotics up-regulated biofilm-associated genes. In particular, atlE and icaA were up-regulated 0.062 to 1.16 and 0.078 to 1.48 folds, respectively, for cloxacillin, 0.11 to 0.8, and 0.1 to 1.3 folds for cefazolin, 0.18 to 0.98, and 0.19 to 1.4 folds, respectively, for clindamycin. In contrast, the results showed that sub-MIC of vancomycin did not increase the biofilm-associated genes. These findings overall show that exposure to sub-MIC of traditional antibiotics can cause biofilm induction in MRSE, thereby increasing the survival and persistence on various surfaces that worsen the condition of comorbid infections.