Search

In the original manuscript, the platelet activation images of the sample treated groups, Fig. 3c were provided incorrectly.

In the original manuscript, the Figure 2 a-i is inadvertently repeated as Figure 2 a-ii. This mistake has been rectified and the corrected Figure 2 is presented below.

PURPOSE: Enteric fever continues to be an important public health challenge for the developing world. With the emergence of fluoroquinolone resistance in Salmonellae spp. azithromycin is increasingly being used for oral treatment of enteric fever. We investigated the antibiotic susceptibility pattern of azithromycin in Salmonellae spp. isolates from a tertiary care hospital to detect emerging resistance. METHODS: The study assessed the reliability of disc diffusion as a screening test to detect azithromycin resistance by comparing it with the minimum inhibitory concentrations (MICs) of the drug in 100 Salmonellae spp. strains. The strains of Salmonellae spp. showing resistance to azithromycin were further investigated for resistance markers – mphA, mphB, and mef B genes. RESULTS: This study was conducted on 100 Salmonella enterica strains recovered from blood culture samples between 2013 and 2017. Among these isolates, 18 showed resistance to azithromycin by disc diffusion methodology with zones of inhibition

Mohandas A, Kumar PT S, Raja B, et al. Int J Nanomedicine.2015;10(Suppl 1):53–66. The authors have advised that Figure 8B and C (page62) were incorrect in the original manuscript, as theAlginate control group is inadvertently repeated in theAlginate +0.1% nZnO group. Due to this mistake theyhave repeated the entire cell attachment studies usingDAPI. The authors have confirmed that this does not inany way affect the conclusions from Figure 8B and C,and that it is not going to affect the overall conclusionof this published paper. They apologize for any inconvenience.The correct version of Figure 8 is presentedbelow. Read the original article

Compared to the current treatment modalities, the use of an injectable hydrogel system, loaded with antibiotic encapsulated nanoparticles for the purpose of treating Staphylococcus aureus (S. aureus) chronic wound infections have several advantages. These include adhesiveness to infection site, reduced frequency of dressings, sustained drug release, inhibition of bacterial growth, and increased healing. In the present work tigecycline nanoparticles were loaded into chitosan-platelet-rich plasma (PRP) hydrogel. The tigecycline nanoparticles (95 ± 13 nm) were synthesized through ionic cross-linking method using chitosan, tripolyphosphate, and tigecycline and characterized by dynamic light scattering (DLS), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FT-IR). The synthesized nanoparticles and activated PRP powder were mixed with chitosan hydrogel to form a homogeneous gel. Rheology studies have confirmed the shear thinning property, thermal stability, and injectability of the prepared gel systems. The gel system was further assessed for its drug release property and found that it was released in a sustained manner. Hemolysis and blood-clotting assays demonstrated that the gel system was neither a hemolysin nor a hamper to the clotting cascade. Cell viability results showed that these nanoparticles were cyto-compatible. The bioactivity of PRP loaded chitosan gel toward fibroblast cell line was studied using cell proliferation and migration assay. In vitro antibacterial studies revealed that the gel system inhibited bacterial growth to a great extent. The antibacterial activity was further analyzed using ex vivo porcine skin assay. In vivo anti-Staphylococcal activity of the prepared hydrogels was studied using a Drosophila melanogaster infection model. The tigecycline and tigecycline nanoparticle incorporated chitosan gel showed a significant antibacterial activity against S. aureus. Thus, the gel system is an effective medium for antibiotic delivery and can be applied on the infection sites to effectively forestall various skin infections caused by S. aureus.

Chitosan, a polymer from the chitin family has diverse pharmaceutical and bio-medical utility because of its easy widespread availability, non-toxicity, biocompatibility, biodegradability, rich functionalities and high drug-loading capacity. Recent pharmaceutical research has examined the use of chitosan-based systems for drug delivery applications in various diseases. The availability of functional groups permits the conjugation of specific ligands and thus helps to target loaded drugs to the site of infection/inflammation. Slow biodegradation of chitosan permits controlled and sustained release of loaded moieties; reduces the dosing frequency and is useful for improving patient compliance in infectious drug therapy. The muco-adhesion offered by chitosan makes it an attractive candidate for anti-inflammatory drug delivery, where rapid clearance of the active moiety due to the increased tissue permeability is the major problem. The pH-dependent swelling and drug release properties of chitosan present a means of passive targeting of active drug moieties to inflammatory sites.Development of chitosan-based nanoparticulate systems for drug delivery applications is reviewed. The current state of chitosan-based nanosystems; with particular emphasis on drug therapy in inflammatory and infectious diseases is also covered.The authors believe that chitosan-based nanosystems, due to the special and specific advantages, will have a promising role in the management of infectious and inflammatory diseases.

The treatment of infectious diseases is still a serious issue owing to the increased antimicrobial resistance by pathogens. The pathogens hide in the intracellular environment, where it is difficult for the drugs to reach at therapeutic dosage levels. Also the drug loses its efficiency at certain environments before it reaches the pathogens. This will in turn ask for frequent administration and high drug dosage, resulting in toxicity issues. This calls for the need of nanoparticles that can specifically deliver drugs to the pathogen-inhabited cell. Biodegradation, mass production, equal biodistribution, and long shelf-life of nanomaterials render them attractive substitutes for biomedical purposes. Surface functionalization of nanoparticles by biomolecules has steered a new way for tempering with the pharmacokinetics and pharmacodynamics of the drugs as well as improving the effectiveness of targeted drugs. The opportunity of therapeutic molecule being affixed to the nanoparticles by chemical modification has presented a unique drug delivery alternative. These stratagems are expected to reduce drug degradation and loss, enhance drug availability, and unlock new outlooks for drug delivery.

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb) and is a major public health concern. According to the 2017 WHO report, global burden of TB infection was 10.4 million people causing the mortality rate of ~1.6 million. The rapid emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB is of major concern in anti-TB drug discovery. There are different druggable targets and its pathways involved in the virulence, which include Mtb cell wall, replication and transcription, regulatory, protein synthesis, membrane transport, and energy production which need to be explored for efficient killing of the bacteria. The ability of the tubercle bacilli to remain within the host intracellular compartment is of other major concern in TB therapy. Thus, to tackle the TB drug resistance, potent inhibitors with novel mechanism of action of different Mtb druggable targets need to be discovered. Three-dimensional structure of different Mtb target was solved for structure-based drug design. The current chapter focuses on some of the key druggable targets in Mtb and also the recent advances in target-based drug designing in the area of anti-tubercular drug discovery.

The intracellular and biofilm associated bacterial infections are difficult to treat due to the resistance potential of the organisms toward commonly used antimicrobial agents. Nanoparticles have promising future in the development of new therapeutics because of their easy functionalization and unique mode of action. This book chapter consists of three parts. The first two parts explain the limitations in the treatment of intracellular and biofilm infections in the current scenario. The last part describes how nanoparticles can be employed to tackle the problems of drug resistance and the latest research studies conducted regarding the same.

Staphylococcus aureus is a major pathogen causing skin infections and currently treated with topical antibiotic preparations like bacitracin, triple antibiotic ointment (neomycin, polymixin B, and bacitracin), gentamicin or mupirocin. However, their efficacies are restricted when the infections are caused by drug resistant strains. There is an imperative need for new antibacterial compounds for the management of S. aureus topical infections. Maginfera indica (mango) is reported for its antibacterial efficacy in many traditional plant based medicines. In this study we tested the antibacterial efficacy of the methanol extract of mango leaf against SA113 and S. aureus clinical strains. Mango leaf extract (MLE) was found to be an effective anti-staphylococcal agent, non-mutagenic, and contains phytochemicals such as tannins, saponins, flavanoids, phenols, and coumarins. Further, the mango leaf extract (from stock MLE concentration of 130 mg/ml) containing carbopol hydrogel (MLEC) was prepared and characterized further for biocompatibility, rheological and anti-staphylococcal activities. The antibacterial activity of MLEC hydrogel against S. aureus strains was verified using in vitro and ex vivo porcine skin model. Our results demonstrated MLEC hydrogel formulation may act as superior alternative to currently available topical antiseptic/antibiotic formulations for the treatment of drug resistant staphylococcal infections.

Summary Outbreaks due to multidrug-resistant Candida auris have emerged as a large threat to modern medicine. Since skin colonization and environmental contamination have been identified as a precursor for outbreaks, we evaluated the antifungal activity of ultraviolet-C light using mercury vapour lamp with a peak emission of 254 ± 2 nm and octenidine dihydrochloride against C. auris clinical isolates. Octenidine dihydrochloride was found effective at significantly lower concentrations (0.00005–0.0004%) than those currently used in the clinical setting (0.05–0.1%). Scanning electron microscopy images show destruction of the organism within 6 h of exposure to 0.0005% octenidine dihydrochloride. Ultraviolet-C light could kill all C. auris with 15 min exposure.

Staphylococcus aureus (S. aureus) readily forms biofilms on prosthetic devices such as the pacemakers, heart valves, orthopaedic implants, and indwelling catheters. Its biofilms are recalcitrant to antibiotic therapy and pose a serious burden in the healthcare setting as they drastically increase the treatment cost and morbidity of the patient. Prevention and treatment of staphylococcal biofilms has therefore been an area of active research for the past two decades. While catheters coated with different antiseptics and antibiotics capable of preventing S. aureus biofilm formation have been developed, an effective therapy for the dispersal and treatment of established staphylococcal biofilms is not yet available. Hence, many studies have focused on developing novel therapeutic strategies that can tackle established S. aureus biofilm associated infections. This has led to the identification of different phytochemicals (e.g., tannic acid, ellagic acid, xanthohumol etc), enzymes (e.g., Dnases, lysostaphin, α-amylase, hyaluronidase and proteases etc.), sulfahydrl compounds (e.g., dithiothreitol, 2-mercaptoethanol), nanoparticles (e.g., gold, silver, iron, copper and selenium), phage cocktails, antibodies and metal chelators. Apart from the conventional techniques, the therapeutic effects of ultra sound, shock waves and photodynamic therapy for treating S. aureus biofilms are also being investigated. Clinical validation of these studies will equip the medical field with alternate preventive and treatment methods against staphylococcal biofilm infections. This review provides recent updates on the preventive and therapeutic strategies explored to eradicate staphylococcal biofilm formation and related infections.

Majority of the chronic wounds are infected with bacteria like Staphylococcus aureus (S. aureus). The deep tissue infections are difficult to treat using topical antibiotics, due to their poor tissue penetration. In order to treat S. aureus deep tissue infections we have developed an antibiotic delivery system using chitosan nanoparticles (CNPs). To enhance their tissue penetration these CNPs were further coated using lecithin (CLNPs). Antibiotic tigecycline was loaded into chitosan nanoparticles (tCNPs) and then coated with lecithin to generate lecithin coated tigecycline loaded chitosan nanoparticles (tCLNPs). The prepared nanoparticles were characterized using DLS, SEM, TEM and FT-IR. The prepared CNPs, tCNPs, CLNPs and tCLNPs have the size range of 85 ± 10, 90 ± 18, 188 ± 5 and 235 ± 20 nm, respectively. The tCLNPs shows more sustained release pattern of tigecycline. The antibacterial activity of the developed nanoparticles was confirmed against laboratory and clinical strains of S. aureus using in vitro and ex vivo experiments. The ex vivo skin and muscle permeation study ensures the enhanced delivery of tigecycline to the deeper tissue. The prepared nanoparticles were hemo-compatible and cyto-compatible. Our study suggests that the prepared tCLNPs can be effectively used for the treatment of S. aureus infected wounds.

Salmonella Paratyphi A is a food-borne Gram-negative pathogen and a major public health challenge in the developing world. Upon reaching the intestine, S. Paratyphi A penetrates the intestinal epithelial barrier; and infects phagocytes such as macrophages and dendritic cells. S. Paratyphi A surviving within macrophages is protected from the lethal action of antibiotics due to their poor penetration into the intracellular compartments. Hence we have developed chloramphenicol loaded chondroitin sulfate (CS-Cm Nps) and dextran sulfate (DS-Cm Nps) nanoparticles through ionotropic-gelation method for the intracellular delivery of chloramphenicol. The size of these nanoparticles ranged between 100 and 200 nm in diameter. The encapsulation efficiency of both the nanoparticles was found to be around 65%. Both the nanoparticles are found to be non-hemolytic and non-toxic to fibroblast and epithelial cells. The prepared nanoparticles exhibited sustained release of the drug of up to 40% at pH 5 and 20–25% at pH 7.0 after 168 h. The anti-microbial activities of both nanoparticles were tested under in vitro and ex vivo conditions. The delivery of DS-Cm Nps into the intracellular compartments of the macrophages was 4 fold more compared to the CS-Cm Nps which lead to the enhanced intracellular antimicrobial activity of Ds-Cm Nps. Enhanced anti-microbial activity of Ds-Cm Nps was further confirmed in an ex vivo chicken intestine infection model. Our results showed that Cm loaded DS Nps can be used to treat intracellular Salmonella infections.

A dysfunctional prothrombin gene characterized by novel point mutation at Arg553 to Gln residue in Deep vein thrombosis (DVT) patient which we designated as "Prothrombin Amrita" was previously reported from our lab. The mutation occurred at nucleotide 20030 in exon 14 and was confirmed by restriction enzyme digestion. Arg553 has been reported as one of the key residues for the binding of cofactor Na+ ion in the thrombin protein. Structural analysis revealed the molecular mechanism behind the coagulant form of thrombin due to point Arg553Gln mutation near the cofactor Na+ ion region. Molecular electrostatic potential maps and molecular dynamics (MD) simulation of the wild type and mutated thrombin showed the key role played by the Na+ ion for its coagulant mechanism by analysing the charge distribution and nature of the hydrogen bonding at the mutated region of interest. We observed maintenance of the fast or procoagulant form of dysfunctional prothrombin due to changes in the charge distribution by this mutation and thereby also keeping strong hydrogen bonding network revealed by MD simulation between prothrombin and Na+ ion. This molecular mechanism might be the main cause for DVT in patients with this dysfunctional prothrombin gene.

Curcumin is a diaryl heptanoid of curcuminoids class obtained from Curcuma longa. It possesses various biological activities like anti-inflammatory, hypoglycemic, antioxidant, wound-healing, and antimicrobial activities. Chitosan is a biocompatible, biodegradable and non-toxic natural polymer which enhances the adhesive property of the skin. Chemical conjugation will leads to sustained release action and to enhance the bioavailability. This study aims to synthesis and characterize biocompatible curcumin conjugated chitosan microspheres for bio-medical applications. The Schiff base reaction was carried out for the preparation of curcumin conjugated chitosan by microwave method and it was characterised using FTIR and NMR. Curcumin conjugated chitosan microspheres (CCCMs) were prepared by wet milling solvent evaporation method. SEM analysis showed these CCCMs were 2-5μm spherical particles. The antibacterial activities of the prepared CCCMs were studied against Staphylococcus aureus and Escherichia coli, the zone of inhibition was 28mm and 23mm respectively. Antioxidant activity of the prepared CCCMs was also studied by DPPH and H2O2 method it showed IC50 esteem value of 216μg/ml and 228μg/ml, and anti-inflammatory activity results showed that CCCMs having IC50 value of 45μg/ml. The results conclude that the CCCMs having a good antibacterial, antioxidant and anti-inflammatory activities. This, the prepared CCCMs have potential application in preventing skin infections.

Intercellular Candida glabrata infections are difficult to treat due to poor penetration of drugs into the fungal niche. Delivering amphotericin B (Amp B) into the macrophages where the pathogen inhabits is an effective solution. We are studying the macrophage targeting proficiency of ɩ-carrageenan for the delivery of Amp B using gelatin A nanoparticles (GNPs). The choice of gelatin A was the outcome of in silico inspections where the amino functionalized polymer having the best docking score with Amp B was selected. We prepared a sustained release formulation of amp B loaded carboxymethyl ɩ-carrageenan conjugated gelatin nanoparticles (CMC-Amp B-GNPs) with size 343±12nm and -25±5.3mV zeta potential. The formulations were found to be stable, biocompatible and non-haemolytic. Flow cytometry analysis showed 3 fold higher uptake of CMC-GNPs compared to the GNPs by RAW 264.7 cells. CMC-Amp B-GNPs showed enhanced antifungal activity than bare Amp B and Amp B-GNPs.

Background Candida parapsilosis is recognized as a species complex: Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis are three distinct but closely related species. Aims To determine the species and antifungal susceptibility of members of the C. parapsilosis complex, isolated from clinical samples. Methods Isolates identified as C. parapsilosis complex by VITEK® 2 system were included. Antifungal susceptibility test was done using the VITEK® 2 semi-automated system. The distribution of the species in the complex was determined by multiplex PCR. Results Among the seventy-seven C. parapsilosis complex isolates, C. parapsilosis sensu stricto (57.1%) was the commonest species, followed by C. orthopsilosis (40.2%) and C. metapsilosis (2.5%). All three species were susceptible to amphotericin B, caspofungin and micafungin. Among C. parapsilosis sensu stricto isolates, 16% were resistant to fluconazole while 2.2% showed dose dependent susceptibility. Also, 18.2% of C. parapsilosis sensu stricto isolates showed dose dependent susceptibility to voriconazole. Conclusions C. parapsilosis sensu stricto was the most commonly isolated member of the C. parapsilosis complex and it showed high resistance to fluconazole. A high prevalence of C. orthopsilosis (40.2%) was also noted.

Our review is focused on the use of methotrexate in drug therapy of two autoimmune diseases, psoriasis and rheumatoid arthritis (RA). The article describes the pathogenesis of psoriasis and RA, the role of methotrexate in the treatment of these diseases with more focused review on the mechanism behind the clinical benefits of methotrexate therapy. Methotrexate due to its cytotoxic, anti-inflammatory and immune modulatory activities provides clinical benefits in the therapy of the selected diseases. This review also gives a panorama of the problems associated with the use of methotrexate in the selected diseases and the guidelines provided by FDA for its safe use. The novel colloidal drug delivery systems of methotrexate, with particular emphasis on advantages offered by liposomal formulation, niosomal gel, hydrogel, albumin conjugates, nanoparticles and nano structured lipid carriers in psoriasis and RA are also reviewed. It seemed that the use of newer colloidal carriers with improved skin permeability by minimizing its systemic availability will be a useful strategy to reduce the toxic effects of the drug in psoriatic patients. In rheumatoid arthritis patients, the development of newer therapeutic strategies using appropriate targeting ligands that specifically deliver the drug to the inflamed joint space will help to overcome its toxic effects by minimizing the systemic exposure.

A cut or break on the surface of the skin is usually referred to as a wound. Any wound has a potential to heal by itself through a complex cascade of events. However, some wounds show delayed healing due to their underlying physiology and are referred to as chronic wounds like diabetic ulcers, venous ulcers, pressure ulcers and chronic infected ulcers. Extensive care has to be taken for the management of chronic wounds and these have become a major concern in the current medical scenario. The use of bioactive molecules or in other words the molecules that can actively interact with the wound environment and help in wound healing are gaining much importance. The incorporation of bioactive molecules into a suitable matrix system which not only provide a controlled release of the molecules, but also enable better exudate management is desired to overcome the shortcomings of the conventional treatment modalities. A major problem associated with chronic wounds is that they are easily prone to infections. In such cases, the topical delivery of antibiotics helps eliminate infection. However, the continuous use of high dose of antibiotics has led to the development of multi drug resistant bacterial strains. To overcome these issues, other broad-spectrum antimicrobial agents like antiseptics, metallic nanoparticles and antimicrobial peptides are being adopted nowadays. Growth factors play a major role in the wound healing cascade, thus topical delivery of growth factor from a suitable matrix is an interesting strategy. The delivery of nucleic acids with the aid of suitable vectors for either silencing a particular gene or over expressing a gene of interest is also being investigated nowadays. This review is an attempt to draw light over some of the recent approaches adopted for the treatment of chronic wounds using bioactive molecules like antibiotics, antiseptics, metallic nanoparticles or ions, growth factors and nucleic acids.

Bacterial cell surface adhesins play a major role in facilitating host colonization and subsequent establishment of infection. The surface of Mycobacterium tuberculosis, owing to the complex architecture of its cell envelope, expresses numerous adhesins with varied chemical nature, including proteins, lipids, lipoproteins, glycoproteins and glycopolymers. Studies on mycobacterial adhesins show that they bind with multifarious host receptors and extracellular matrix (ECM) components. In this review we have highlighted the adhesins that are abundantly present on the mycobacterial surface and their interactions with host receptors. M. tuberculosis interacts with various host cell surface receptors such as toll like receptors, C-type lectin receptors, scavenger receptors, and Fc and complement receptors. Apart from these, ECM components like fibronectin, collagen, elastin, laminin, fibrillin and vitronectin also provide binding sites for surface adhesins of the tubercle bacilli. M. tuberculosis adhesins include proteins with and without signal peptide sequence and transmembrane proteins. Other surface adhesin macromolecules of M. tuberculosis comprises of lipids, glycolipids and glycopolymers. The interaction between the mycobacterial adhesins and their host receptors result in adhesion of the microbe to the host cells, induction of immune response and aid in the pathogenesis of the disease. A thorough understanding of the different M. tuberculosis surface adhesins and host receptors will provide a better picture of interaction between them at molecular level. The information gained on adhesins and host receptors will prove beneficial in developing novel therapeutic strategies such as the use of anti-adhesin molecules to hinder the adhesion of bacteria to the host cells, thereby preventing establishment of infection. The surface molecules discussed in this review will also benefit in identification of new drug targets, diagnostic markers or vaccine candidates against the deadly pathogen.

Polymicrobial infections involving Staphylococcus aureus exhibit enhanced disease severity and morbidity. We reviewed the nature of polymicrobial interactions between S. aureus and other bacterial, fungal, and viral cocolonizers. Microbes that were frequently recovered from the infection site with S. aureus are Haemophilus influenzae , Enterococcus faecalis , Pseudomonas aeruginosa , Streptococcus pneumoniae , Corynebacterium sp., Lactobacillus sp., Candida albicans , and influenza virus. Detailed analyses of several in vitro and in vivo observations demonstrate that S. aureus exhibits cooperative relations with C. albicans , E. faecalis , H. influenzae , and influenza virus and competitive relations with P. aeruginosa , Streptococcus pneumoniae , Lactobacillus sp., and Corynebacterium sp. Interactions of both types influence changes in S. aureus that alter its characteristics in terms of colony formation, protein expression, pathogenicity, and antibiotic susceptibility.

Background The objective of this study was to fabricate, characterize and evaluate in vitro, an injectable calcium sulfate bone cement beads loaded with an antibiotic nanoformulation, capable of delivering antibiotic locally for the treatment of periodontal disease. Methods Tetracycline nanoparticles (Tet NPs) were prepared using an ionic gelation method and characterized using DLS, SEM, and FTIR to determine size, morphology, stability and chemical interaction of the drug with the polymer. Further, calcium sulfate (CaSO4) control and CaSO4-Tet NP composite beads were prepared and characterized using SEM, FTIR and XRD. The drug release pattern, material properties and antibacterial activity were evaluated. In addition, protein adsorption, cytocompatibility and alkaline phosphatase activity of the CaSO4-Tet NP composite beads in comparison to the CaSO4 control were analyzed. Results Tet NPs showed a size range of 130 ± 20 nm and the entrapment efficiency calculated was 89%. The composite beads showed sustained drug release pattern. Further the drug release data was fitted into various kinetic models wherein the Higuchi model showed higher correlation value (R2 = 0.9279) as compared to other kinetic models. The composite beads showed antibacterial activity against Staphylococcus aureus and Escherichia coli. The presence of Tet NPs in the composite bead didn't alter its cytocompatibility. In addition, the composite beads enhanced the ALP activity of hPDL cells. Conclusions The antibacterial and cytocompatible CaSO4-Tet NP composite beads could be beneficial in periodontal management to reduce the bacterial load at the infection site. General significance Tet NPs would deliver antibiotic locally at the infection site and the calcium sulfate cement, would itself facilitate tissue regeneration.

Staphylococcus aureus is one of the major causes of skin and soft tissue infections. In this study we compared the antimicrobial activity of two different TiO2 nanoformulations against Staphylococcus aureus. We synthesized TiO2 nanoparticles of approximately 80 nm diameter and TiO2 nanowires of approximately 100 nm diameter. Both nanoformulations possess anti-microbial activity; were non-hemolytic and cytocompatible. However, the anti-staphylococcal activity of TiO2 nanowires was better than the nanoparticles. In broth culture, growth of S. aureus was only partially inhibited by 2% and 4 wt% TiO2 nanoparticles and completely inhibited by TiO2 nanowires till 24 h. TiO2 nanowires treated S. aureus cells exhibits diminished membrane potential than nanoparticle treated cells. The anti-microbial properties of both TiO2 nanoformulations were validated using ex vivo porcine skin model which supplements the in vitro assays. Anti-bacterial activity of the TiO2 nanowires were also validated against multi drug resistant pathogenic strains of S. aureus, showing the clinical potency of the TiO2 nanowires compared to its nanoparticles.

In this work, we developed 120-150 nm sized nickel nanoparticles loaded chitin nanogels (Ni-Chitin NGs) by regeneration chemistry approach to investigate and determine its cytocompatibility and antibacterial activity against Staphylococcus aureus. The nickel nanoparticles were prepared by hydrothermal method. The prepared Ni-Chitin NGs were well characterized by SEM, FTIR, TG/DTA/DTG and XRD and the in vitro cytocompatibility was tested on A549 and L929 cells which showed that they are completely non-toxic. Ni-Chitin NGs showed better toxicity to the bacterial strains when compared to previous study with other nanoparticles using serial dilution method. The rhodamine labeled-Ni-Chitin NGs showed cellular localization on both L929 and A549 cells without perturbing their cellular constituents. These studies showed that the Ni-Chitin NGs could be used for various applications in biomedical filed.

The innate immune system constitutes the first line of defence against invading microbes. The basis of this defence resides in the recognition of defined structural motifs of the microbes called "Microbial associated molecular patterns" that are absent in the host. Cell wall, the outer layer of both bacterial and fungal cells, a unique structure that is absent in the host and is recognized by the germ line encoded host receptors. Nucleotide oligomerization domain proteins, peptidoglycan recognition proteins and C-type lectins are host receptors that are involved in the recognition of bacterial cell wall (usually called peptidoglycan), whereas fungal cell wall components (N- and O-linked mannans, β-glucans etc.) are recognized by host receptors like C-type lectins (Dectin-1, Dectin-2, mannose receptor, DC-SIGN), Toll like receptors-2 and -4 (TLR-2 and TLR-4). These recognitions lead to activation of a variety of host signaling cascades and ultimate production of anti-microbial compounds including phospholipase A2, antimicrobial peptides, lysozyme, reactive oxygen and nitrogen species. These molecules act in cohort against the invading microbes to eradicate infections. Additionally pathogen recognition leads to the production of cytokines, which further activate the adaptive immune system. Both pathogenic and commensal bacteria and fungus use numerous strategies to subvert the host defence. These strategies include bacterial peptidoglycan glycan backbone modifications by O-acetylation, N-deacetylation, N-glycolylation and stem peptide modifications by amidation of meso-Diaminopimelic acid; fungal cell wall modifications by shielding the β-glucan layer with mannoproteins and α-1,3 glucan. This review focuses on the recent advances in understanding the role of bacterial and fungal cell wall in their innate immune recognition and evasion strategies.

Poor bioavailability of antifungal drugs due to the various protective mechanisms of the eye is a serious concern for the treatment of corneal fungal infections in today's world. The use of nanosystems that can improve the bioavailability of these antifungal drugs is relatively a new idea being conceived and here we have synthesized fluconazole loaded chitin nanogels (Flu-CNGs) which can be used for the treatment of corneal fungal infections. These nanogels were characterized using DLS, Zeta potential, SEM, FTIR and TG/DTA. The prepared Flu-CNGs have controlled release pattern which is ideal for the continuous availability of fluconazole over a longer period of time for an effective fungal treatment. Flu-CNGs are haemocompatible, cytocompatible and also showed very good cell uptake in human dermal fibroblast cells and penetration to the deeper sections of the porcine cornea with no signs of destruction or inflammation to corneal cells as shown in ex vivo permeation studies.

Nanosurface modification of Titanium (Ti) implants and prosthesis is proved to enhance osseointegration at the tissue-implant interface. However, many of these products lack adequate antibacterial capability, which leads to implant loosening. As a curative strategy, in this study, nanotextured Ti substrates embedded with silver nanoparticles were developed through a single step hydrothermal processing in an alkaline medium containing silver nitrate at different concentrations (15, 30 and 75μM). Scanning electron micrographs revealed a non-periodically oriented nanoleafy structure on Ti (TNL) decorated with Ag nanoparticles (nanoAg), which was verified by XPS, XRD and EDS analysis. This TNLAg substrate proved to be mechanically stable upon nanoindentation and nanoscratch tests. Silver ions at detectable levels were released for a period of ~28days only from substrates incorporating higher nanoAg content. The samples demonstrated antibacterial activity towards both Escherichia coli and Staphylococcus aureus, with a more favorable response to the former. Simultaneously, Ti substrates incorporating nanoAg at all concentrations supported the viability, proliferation and osteogenic differentiation of mesenchymal stem cells. Overall, nanoAg incorporation into surface modified Ti via a simple one-step thermochemical method is a favorable strategy for producing implants with dual characteristics of antibacterial activity and cell compatibility.

Tissue injuries that usually heal slowly and tend to reoccur are referred to as chronic wounds. These wounds are associated with severe tissue loss and are also heavily contaminated. The rate of he...

Background: This study was performed to evaluate and compare the clinical and antimicrobial efficacy of subgingival irrigation with tetracycline and povidone‑iodine as an adjunct to nonsurgical periodontal therapy. Materials and Methods: Twenty subjects with chronic moderate periodontitis were recruited in this split‑mouth study with probing pocket depth of >3 and ≤5 mm and clinical attachment loss of 3–4 mm in relation to 16, 36, and 46. In each subject, three selected periodontal pockets were assigned to receive one out of three irrigants (1) sterile water (control) in 16; (2) tetracycline at 10 mg/ml in 36; (3) 2% povidone‑iodine in 46, and these sites were designated as Group A, Group B, and Group C, respectively. Plaque score, gingival score, pocket probing depth, and clinical attachment level were evaluated before treatment and at 1 and 3 months posttreatment. Multiplex polymerase chain reaction was used to detect Porphyromonas gingivalis and Tannerella forsythensis which have been implicated as the major risk factors for periodontal disease. Subgingival plaque collected before treatment and at 1 and 3 months posttreatment. Data were analysed using ANOVA and repeated measure ANOVA. Results were considered significant if P < 0.05. Results: Clinical and microbiological parameters were reduced posttreatment, the reduction being significantly higher in Group B compared to Group C. Conclusion: It can be concluded that chemical and mechanical therapies were of slight benefit in the treatment of chronic moderate periodontitis, and there was an adjunctive effect of significance when scaling and root planing was combined with a single subgingival irrigation with tetracycline or povidone‑iodine in lower concentration. Key Words: Polymerase chain reaction, povidone‑iodine, subgingival irrigation, tetracycline

We developed chitin hydrogel/nano ZnO composite bandages using chitin hydrogel and ZnO nanoparticles (nZnO). The homogenized mixture of chitin hydrogel and nZnO was freeze-dried to obtain micro-porous composite bandages. The prepared nanocomposite bandages were characterized using FT-IR, XRD and SEM. In addition, blood clotting, antibacterial, swelling, cytocompatibility and cell attachment capability of the prepared nanocomposite bandages were evaluated. The nanocomposite bandages showed enhanced swelling, blood clotting and antibacterial activity. The incorporation of nZnO helped to attain antibacterial activity. Cytocompatibility studies were carried out using human dermal fibroblast (HDF) cells proved the non-toxic nature of the composite bandages. HDF cell attachment and infiltration analysis showed that the cells were attached and penetrated into the interior (250 microm) of the nanocomposite bandages. These studies revealed that, this nanocomposite can be used for burn, diabetic and chronic wound defects.

β-chitin hydrogel/nZnO composite bandage was fabricated and evaluated in detail as an alternative to existing bandages. β-chitin hydrogel was synthesized by dissolving β-chitin powder in Methanol/CaCl2 solvent, followed by the addition of distilled water. ZnO nanoparticles were added to the β-chitin hydrogel and stirred for homogenized distribution. The resultant slurry was frozen at 0°C for 12 h. The frozen samples were lyophilized for 24 h to obtain porous composite bandages. The bandages showed controlled swelling and degradation. The composite bandages showed blood clotting ability as well as platelet activation, which was higher when compared to the control. The antibacterial activity of the bandages were proven against Staphylococcus aureus (S. aureus) and Escherichia coli (E.coli). Cytocompatibility of the composite bandages were assessed using human dermal fibroblast cells (HDF) and these cells on the composite bandages were viable similar to the Kaltostat control bandages and bare β-chitin hydrogel based bandages. The viability was reduced to 50–60% in bandages with higher concentration of zinc oxide nanoparticles (nZnO) and showed 80–90% viability with lower concentration of nZnO. In vivo evaluation in Sprague Dawley rats (S.D. rats) showed faster healing and higher collagen deposition ability of composite bandages when compared to the control. The prepared bandages can be used on various types of infected wounds with large volume of exudates.

Intracellular bacterial infections are recurrent, persistent and are difficult to treat because of poor penetration and limited availability of antibiotics within macrophages and epithelial cells. We developed biocompatible, 200 nm sized tetracycline encapsulated O-carboxymethyl chitosan nanoparticles (Tet-O-CMC Nps) via ionic gelation for its sustained delivery of Tet into cells. S. aureus binds and aggregates with Tet-O-CMC Nps increasing drug concentrations at the infection site. Tet-O-CMC Nps were sixfold more effective in killing intracellular S. aureus compared to Tet alone in HEK-293 and differentiated THP1 macrophage cells proving it to be an efficient nanomedicine to treat intracellular S. aureus infections.

Surgical wounds and implant-associated Staphylococcus aureus and Pseudomonas aeruginosa infections are often difficult to treat because of limited susceptibility of several of these strains to conventional antibiotics. As a result, there is a constant need for new alternative drugs. The aim of this study was to investigate the antimicrobial properties of Lactobacillus fermentum, a probiotic bacterium, which we have isolated from colonic biopsies. The inhibition of S. aureus and P. aeruginosa growth was evaluated by coincubating with L. fermentum strains. Growth inhibition was tested for several of their clinical isolates using agar well diffusion assays. For biofilm assay S. aureus and P. aeruginosa were grown on the glass slides and in 96-well plates in presence of 2.5 µg/ml culture filtrate of L. fermentum. Biofilms were photographed using confocal microscope or stained with 0.1% crystal violet. Reduction in the cytotoxicity of S. aureus and P. aeruginosa was observed in presence of 2.5 µg/ml L. fermentum-spent media. Using in vitroexperiments, we showed that L. fermentum-secreted compound(s) inhibits the growth, cytotoxicity and biofilm formation of several S. aureus and P. aeruginosa strains. Compound(s) present in the culture supernatant of L. fermentum may have promising applications in treating hospital-acquired infections.

Intestinal Na(+)-coupled glucose transporter SGLT1 determines the rate of glucose transport, which in turn influences glucose-induced insulin release and development of obesity. The present study explored effects of Gum Arabic (GA), a dietary polysaccharide from dried exudates of Acacia Senegal, on intestinal glucose transport and body weight in wild-type C57Bl/6 mice. Treatment with GA (100 g/l) in drinking water for four weeks did not affect intestinal SGLT1 transcript levels but decreased SGLT1 protein abundance in jejunal brush border membrane vesicles. Glucose-induced jejunal short-circuit currents revealed that GA treatment decreased electrogenic glucose transport. Drinking a 20% glucose solution for four weeks significantly increased body weight and fasting plasma glucose concentrations, effects significantly blunted by simultaneous treatment with GA. GA further significantly blunted the increase in body weight, fasting plasma glucose and fasting insulin concentrations during high fat diet. In conclusion, the present observations disclose a completely novel effect of gum arabic, i.e. its ability to decrease intestinal SGLT1 expression and activity and thus to counteract glucose-induced obesity.

In Staphylococcus , the twin-arginine translocation (Tat) pathway is present only in some species and is composed of TatA and TatC. The tatAC operon is associated with the fepABC operon, which encodes homologs to an iron-binding lipoprotein, an iron-dependent peroxidase (FepB), and a high-affinity iron permease. The FepB protein has a typical twin-arginine (RR) signal peptide. The tat and fep operons constitute an entity that is not present in all staphylococcal species. Our analysis was focused on Staphylococcus aureus and S. carnosus strains. Tat deletion mutants ( ΔtatAC ) were unable to export active FepB, indicating that this enzyme is a Tat substrate. When the RR signal sequence from FepB was fused to prolipase and protein A, their export became Tat dependent. Since no other protein with a Tat signal could be detected, the fepABC - tatAC genes comprise not only a genetic but also a functional unit. We demonstrated that FepABC drives iron import, and in a mouse kidney abscess model, the bacterial loads of Δ tatAC and Δ tat - fep mutants were decreased. For the first time, we show that the Tat pathway in S. aureus is functional and serves to translocate the iron-dependent peroxidase FepB.

Over six million people in nine districts of West Bengal, India are exposed to very high levels of arsenic primarily through their drinking water. More than 300,000 people showed arsenic-induced skin lesions in these districts. This is regarded as the greatest arsenic calamity in the world. Chronic arsenicosis causes varied dermatological signs ranging from pigmentation changes, hyperkeratosis to non-melanocytic cancer of skin, and also malignancies in different internal organs. Higher incidences of opportunistic infections are found in the arsenic-exposed individuals, indicating that their immune systems may be impaired somehow. We have thus investigated the effect of arsenic on T-cell proliferation and cytokine secretion in 20 individuals with arsenic-induced skin lesions and compared the results with 18 arsenic-unexposed individuals. A marked dose-dependent suppression of Concanavalin A (Con A) induced T-cell proliferation was observed in the arsenic-exposed individuals compared with the unexposed ( P

Sepsis is paralleled by anemia, an effect partially resulting from eryptosis, the suicidal death of erythrocytes. Eryptosis is characterized by cell membrane scrambling with phosphatidylserine exposure at the erythrocyte surface. Pathogen-induced eryptosis may partially result from interaction of bacterial cell wall components such as lipoproteins with the erythrocyte cell membrane. The present study explored, whether the synthetic lipopeptide Pam3CSK4 mimicking the acylated amino terminus of bacterial lipoproteins triggers eryptosis. According to annexin-V-binding in FACS analysis, Pam3CSK4 (1 microg/ml) stimulated phosphatidylserine exposure, an effect significantly blunted in the nominal absence of Ca(2+). According to Fluo3 fluorescence, Pam3CSK4 increased cytosolic Ca(2+) activity and moderately stimulated erythrocytic ceramide formation, both major triggers of eryptosis. In conclusion, bacterial lipoproteins participate in the stimulation of erythrocyte cell membrane scrambling by bacterial cell wall components. Thus, lipoprotein-dependent suicidal erythrocyte death may contribute to the pleotropic effects of sepsis.

The prevalence of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) in hospitalised and community patients is of significant public health concern. The aim of this study was to estimate the faecal carriage rate of ESBL-PE in hospitalised patients and healthy asymptomatic individuals coming for health check-up. Non-repetitive, consecutive stool samples from 480 adults (260 healthy individuals and 220 hospitalised patients) aged ≥18 years from November 2011 to July 2013 were screened using MacConkey agar supplemented with ceftazidime. All screen-positive isolates were identified to species level and were tested for ESBL production. Representative ESBL-PE isolates were subjected to susceptibility testing and multiplex ESBL PCR. The faecal carriage rate of ESBL-PE was found to be 62.7% among hospitalised patients and 33.8% among healthy asymptomatic individuals. The most common ESBL-PE was Escherichia coli (70.3% and 78.4% in hospitalised patients and healthy individuals, respectively), followed by Klebsiella pneumoniae (26.8% and 17.0%). ESBL-PE showed the highest sensitivity to carbapenems (85% and 100%, respectively), followed by amikacin (67.2% and 98%), cefoperazone/sulbactam (27.8% and 88.2%) and piperacillin/tazobactam (18% and 74.5%). Ciprofloxacin exhibited a high level of resistance among both groups. Molecular analysis for ESBL genes showed a predominance of the CTX-M gene. In conclusion, the faecal carriage rate of ESBL-PE among hospitalised patients was almost double that of healthy individuals. Carriage of carbapenem-resistant isolates is emerging among hospitalised patients. The spread of these organisms in the community merits radical measures to improve sanitation and implement antibiotic stewardship.

Many Gram-positive bacteria produce lipoteichoic acid (LTA) polymers whose physiological roles have remained a matter of debate because of the lack of LTA-deficient mutants. The ypfP gene responsible for biosynthesis of a glycolipid found in LTA was deleted in Staphylococcus aureus SA113, causing 87% reduction of the LTA content. Mass spectrometry and nuclear magnetic resonance spectroscopy revealed that the mutant LTA contained a diacylglycerol anchor instead of the glycolipid, whereas the remaining part was similar to the wild-type polymer except that it was shorter. The LTA mutant strain revealed no major changes in patterns of cell wall proteins or autolytic enzymes compared with the parental strain indicating that LTA may be less important in S. aureus protein attachment than previously thought. However, the autolytic activity of the mutant was strongly reduced demonstrating a role of LTA in controlling autolysin activity. Moreover, the hydrophobicity of the LTA mutant was altered and its ability to form biofilms on plastic was completely abrogated indicating a profound impact of LTA on physicochemical properties of bacterial surfaces. We propose to consider LTA and its biosynthetic enzymes as targets for new antibiofilm strategies.

Candida albicans and Staphylococcus aureus are opportunistic pathogens. Despite causing a number of independent infections, both pathogens can co-infect to cause urinary tract infections, skin infections, biofilm associated infections, sepsis and pneumonia. Infections of these two pathogens especially their biofilm associated infections are often difficult to treat using currently available anti-bacterial and anti-fungal agents. In order to identify a common anti-microbial agent which could confer a broad range of protection against their infections, we screened several phytochemicals and identified plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone), a phytochemical from Plumbago species as a potent antimicrobial agent against S. aureus and C. albicans, with a minimum inhibitory concentration of 5μg/ml. Antimicrobial activity of plumbagin was validated using an ex-vivo porcine skin model. For better understanding of the antimicrobial activity of plumbagin, a Drosophila melanogaster infection model was used, where D. melanogaster was infected using S. aureus and C. albicans, or with both organisms. The fly's survival rate was dramatically increased when infected flies were treated using plumbagin. Further, plumbagin was effective in preventing and dispersing catheter associated biofilms formed by these pathogens. The overall results of this work provides evidence that plumbagin, possesses an excellent antimicrobial activity which should be explored further for the treatment of S. aureus and C. albicans infections.

Pseudomonas aeruginosa is a leading cause of nosocomial infections and is responsible for ∼10% of all hospital-acquired infections worldwide. It continues to pose a therapeutic challenge because of the high rate of morbidity and mortality associated with it and the possibility of development of drug resistance during therapy. Standard antibiotic regimes against P. aeruginosa are increasingly becoming ineffective due to the rise in drug resistance. With the scope for developing new antibiotics being limited, alternative treatment options are gaining more and more attention. A number of recent studies reported complementary and alternative treatment options to combat P. aeruginosa infections. Quorum sensing inhibitors, phages, probiotics, anti-microbial peptides, vaccine antigens and antimicrobial nanoparticles have the potential to act against drug resistant strains. Unfortunately, most studies considering alternative treatment options are still confined in the pre-clinical stages, although some of these findings have tremendous potential to be turned into valuable therapeutics. This review is intended to raise awareness of several novel approaches that can be considered further for combating drug resistant P. aeruginosa infections.

Human-pathogenic bacteria that are able to cause persistent infections must have developed mechanisms to resist the immune defense system. Lysozyme, a cell wall-lytic enzyme, is one of the first defense compounds induced in serum and tissues after the onset of infection. Recently, we showed that Staphylococcus aureus is resistant to lysozyme by O acetylating its peptidoglycan (PG) by O -acetyltransferase (OatA). We asked the question of which staphylococcal species PG is O acetylated. We applied various methods, such as genome analysis, PCR, Southern blotting, lysozyme sensitivity assay, and verification of O acetylation of PG by high-performance liquid chromatography (HPLC) analysis. PCR analysis using S. aureus -derived oatA primers and Southern blotting did not yield reliable results with other staphylococcal species. Therefore, we used the HPLC-based assay to directly detect PG O acetylation. Our studies revealed that the muramic acid was O acetylated only in pathogenic, lysozyme-resistant staphylococci (e.g., S. aureus , S. epidermidis , S. lugdunensis , and others). All nonpathogenic species were lysozyme sensitive. They can be divided into sensitive species (e.g., S. carnosus , S. gallinarum , and S. xylosus ) and hypersensitive species (e.g., S. equorum , S. lentus , and S. arlettae ). In all lysozyme-sensitive species, the analyzed PG was de-O-acetylated. When we transformed the oatA gene from lysozyme-resistant S. aureus into S. carnosus , the corresponding transformants also became lysozyme resistant.

The major autolysin of Staphylococcus aureus (AtlA) and of Staphylococcus epidermidis (AtlE) are well-studied enzymes. Here we created an atlA deletion mutant in S. aureus that formed large cell clusters and was biofilm-negative. In electron micrographs, the mutant cells were distinguished by rough outer cell surface. The mutant could be complemented using the atlE gene from S. epidermidis. To study the role of the repetitive sequences of atlE, we expressed in Escherichia coli the amidase domain encoded by the gene, carrying no repeat regions (amiE) or two repeat regions (amiE-R1,2), or the three repeat regions alone (R1,2,3) as N-terminal His-tag fusion proteins. Only slight differences in the cell wall lytic activity between AmiE and AmiE-R1,2 were observed. The repetitive sequences exhibit a good binding affinity to isolated peptidoglycan and might contribute to the targeting of the amidase to the substrate. AmiE and AmiE-R1,2 have a broad substrate specificity as shown by similar activities with peptidoglycan lacking wall teichoic acid, O-acetylation, or both. As the amidase activity of AtlA and AtlE has not been proved biochemically, we used purified AmiE-R1,2 to determine the exact peptidoglycan cleavage site. We provide the first evidence that the amidase indeed cleaves the amide bond between N-acetyl muramic acid and L-alanine.

Though pericardial disease is common in patients with renal disease, purulent pericarditis is very rare. We report a fatal case of purulent pericarditis and sepsis due to methicillin-resistant Staphylococcus aureus in a 78-year-old male with systemic hypertension and renal disease along with the molecular characterization of its resistant mechanism.

Surgical debridement of the dead bone and subsequent systemic antibiotic therapy is often ineffective in eliminating Staphylococcus aureus infections in osteomyelitic patients. The recurrence of S. aureus infection is mainly due to the intracellular growth of bacterial colonies within osteoblast cells that protect the organism from extracellular host defences and/or antibiotic therapy. In this study, porous gelatin-hydroxyapatite (HAP) scaffolds with various amounts of ciprofloxacin (1, 2, 5, and 10 wt%) were fabricated by freeze-drying technique and the release of the antibiotic was characterized, as was the efficacy of the released antibiotic against methicillin-sensitive and methicillin-resistant S. aureus. Furthermore, the impact of the released antibiotic on the viability and osteogenic differentiation of human adipose-derived mesenchymal stem cells (ADMSCs) cultured on the scaffolds were assessed. Finally, the efficacy of the released ciprofloxacin to enter the cells and abate intracellularly located S. aureus was evaluated. All the groups of CGHA scaffolds displayed sustained release of ciprofloxacin against S. aureus for 60 days above the minimum inhibitory concentration for the target species with zero-order kinetics and Korsmeyer-Peppas models. While comparing, the released antibiotic from CGHA5 scaffolds was found to be effective at reducing S. aureus through the study period, without detrimental effects on human ADMSC viability or osteogenic potential. When stem cells internalized with S. aureus were cultured onto the drug-loaded scaffolds, a significant reduction in the colony count of internalized bacteria was observed, resulting in the osteogenic differentiation capability of those cells. Our results clearly demonstrate that the ciprofloxacin incorporated gelatin-HAP scaffolds, which were cytocompatible and could target both intracellular and extracellular S. aureus, defining its potential to be used as local drug delivery system.