Efficacy of Short Novel Antimicrobial and Anti-Inflammatory Peptides in a Mouse Model of Methicillin-Resistant Staphylococcus aureus (MRSA) Skin Infection

The therapeutic efficacy of two novel short antimicrobial and anti-inflammatory peptides (RR and RRIKA) was evaluated in a mouse model of staphylococcal skin infection. RR (2%) and RRIKA (2%) significantly reduced the bacterial counts and the levels of proinflammatory cytokines, tumor necrosis factor (TNF)-α, and interleukin (IL)-6, in methicillin-resistant Staphylococcus aureusUSA 300-0114 skin lesions. Furthermore, the combined therapy of RRIKA (1%) and lysostaphin (0.5%) had significantly higher antistaphylococcal and anti-inflammatory activity compared to monotherapy. This study supports the potential use of these peptides for topical treatment of methicillin-resistant Staphylococcus aureus skin infections

Experimentally evaluation of high-performance concrete mixes used for tunnels and containing silica fume and polypropylene fiber after exposed to high temperatures

This work introduces an experimental study to evaluate the effect of elevated temperatures on the mechanical properties of high-performance concrete (HPC) mix with changes in Water-Cementitious ratios, W/(C+SF), Silica Fume percent, SF, and Polypropylene, PP, fiber contents. This mix was typically designed to satisfy the requirements of tunnel concrete. The compressive and indirect tensile strengths were measured at room temperature, RT, and after exposure to 400°C and 800°C. Moreover, SEM micrograph and EDS spot analysis tests were done to evaluate the effect of elevated temperatures. Fifteen mixes of HPC with different ratios of W/(C+SF), SF, and PP fiber were tested. According to the test results, the compressive strength values of design mixes increased significantly after exposure to 400°C. Moreover, using SF = 10%, the results indicated remarkable improvements in the compressive strength at 400°C and 800°C, in the case of the W/(C+SF) ratio of 0.31. On the other hand, the highest effect of the presence of PP fibers was 0.211, depending on variable ratios of the W/(C+SF) ratio and the SF content. In the case of PP=0.106 and SF=10%, the mass loss was higher at exposure to temperatures of 800°C

Repurposing Celecoxib as a Topical Antimicrobial Agent

There is an urgent need for new antibiotics and alternative strategies to combat multidrug-resistant bacterial pathogens, which are a growing clinical issue. Repurposing existing approved drugs with known pharmacology and toxicology is an alternative strategy to accelerate antimicrobial research and development. In this study, we show that celecoxib, a marketed inhibitor of cyclooxygenase-2, exhibits broad-spectrum antimicrobial activity against Gram-positive pathogens from a variety of genera, including Staphylococcus, Streptococcus, Listeria, Bacillus, and Mycobacterium, but not against Gram-negative pathogens. However, celecoxib is active against all of the Gram-negative bacteria tested, including strains of, Acinetobacter, and Pseudomonas, when their intrinsic resistance is artificially compromised by outer membrane permeabilizing agents such as colistin. The effect of celecoxib on incorporation of radioactive precursors into macromolecules in Staphylococcus aureus was examined. The primary antimicrobial mechanism of action of celecoxib was the dose-dependent inhibition of RNA, DNA, and protein synthesis. Further, we demonstrate the in vivo efficacy of celecoxib in a methicillin-resistant S. aureus (MRSA) infected Caenorhabditis elegans whole animal model. Topical application of celecoxib (1 and 2%) significantly reduced the mean bacterial count in a mouse model of MRSA skin infection. Further, celecoxib decreased the levels of all inflammatory cytokines tested, including tumor necrosis factor-α, interleukin-6, interleukin-1 beta, and monocyte chemo attractant protein-1 in wounds caused by MRSA infection. Celecoxib also exhibited synergy with many conventional antimicrobials when tested against four clinical isolates of S. aureus. Collectively, these results demonstrate that celecoxib alone, or in combination with traditional antimicrobials, has a potential to use as a topical drug for the treatment of bacterial skin infections

Repurposing ebselen for Treatment of Multidrug-Resistant Staphylococcal Infections

Novel antimicrobials and new approaches to developing them are urgently needed. Repurposing already-approved drugs with well-characterized toxicology and pharmacology is a novel way to reduce the time, cost, and risk associated with antibiotic innovation. Ebselen, an organoselenium compound, is known to be clinically safe and has a well-known pharmacology profile. It has shown potent bactericidal activity against multidrug-resistant clinical isolates of staphylococcus aureus, including methicillin- and vancomycin-resistant S. aureus (MRSA and VRSA). We demonstrated that ebselen acts through inhibition of protein synthesis and subsequently inhibited toxin production in MRSA. Additionally, ebselen was remarkably active and significantly reduced established staphylococcal biofilms. The therapeutic efficacy of ebselen was evaluated in a mouse model of staphylococcal skin infections. Ebselen 1% and 2% significantly reduced the bacterial load and the levels of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1β), and monocyte chemo attractant protein-1 (MCP-1) in MRSA USA300 skin lesions. Furthermore, it acts synergistically with traditional antimicrobials. This study provides evidence that ebselen has great potential for topical treatment of MRSA skin infections and lays the foundation for further analysis and development of ebselen as a potential treatment for multidrug-resistant staphylococcal infections

Hind-foot correction and stabilization by pins in plaster after surgical release of talipes equino varus feet in older children

Congenital talipes equino varus (CTEV) is a three dimensional deformity and is one of the most common congenital abnormalities affecting the lower limb and can be challenging to manage. Hind-foot deformity is considered the most difficult to treat. Unfortunately, the calcaneus is often small and thus difficult to control during casting after surgical release in severe or relapsed cases. We used three pins to control and maintain the hind foot correction, after surgical release, during casting in 47 cases (59 feet). We introduced a modified, coronal plane, transverse calcaneal pin. This pin is inserted from medial to lateral through the calcaneus to correct the varus mal-positioning of the calcaneus in the sagittal plane and to provide a better control on the small sized, hind-foot during casting. We paid special attention to the final hind-foot deformity after surgery, and the results were favorable after the application of this transverse pin

Repurposing clinical molecule ebselen to combat drug resistant pathogens

Without a doubt, our current antimicrobials are losing the battle in the fight against newly-emerged multidrug-resistant pathogens. There is a pressing, unmet need for novel antimicrobials and novel approaches to develop them; however, it is becoming increasingly difficult and costly to develop new antimicrobials. One strategy to reduce the time and cost associated with antimicrobial innovation is drug repurposing, which is to find new applications outside the scope of the original medical indication of the drug. Ebselen, an organoselenium clinical molecule, possesses potent antimicrobial activity against clinical multidrug-resistant Gram-positive pathogens, including Staphylococcus, Streptococcus, and Enterococcus, but not against Gram-negative pathogens. Moreover, the activity of ebselen against Gram-positive pathogens exceeded those activities determined for vancomycin and linezolid, drugs of choice for treatment of Enterococcus and Staphylococcus infections. The minimum inhibitory concentrations of ebselen at which 90% of clinical isolates of Enterococcus and Staphylococcus were inhibited (MIC90) were found to be 0.5 and 0.25 mg/L, respectively. Ebselen showed significant clearance of intracellular methicillinresistant S. aureus (MRSA) in comparison to vancomycin and linezolid. We demonstrated that ebselen inhibits the bacterial translation process without affecting mitochondrial biogenesis. Additionally, ebselen was found to exhibit excellent activity in vivo in a Caenorhabditis elegans MRSA-infected whole animal model. Finally, ebselen showed synergistic activities with conventional antimicrobials against MRSA. Taken together, our results demonstrate that ebselen, with its potent antimicrobial activity and safety profiles, can be potentially used to treat multidrug resistant Gram-positive bacterial infections alone or in combination with other antibiotics and should be further clinically evaluated. © 2015 Thangamani et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Antibacterial Activity of Novel Cationic Peptides against Clinical Isolates of Multi-Drug Resistant Staphylococcus pseudintermedius from Infected Dogs

Staphylococcus pseudintermedius is a major cause of skin and soft tissue infections in companion animals and has zoonotic potential. Additionally, methicillin-resistant S. pseudintermedius (MRSP) has emerged with resistance to virtually all classes of antimicrobials. Thus, novel treatment options with new modes of action are required. Here, we investigated the antimicrobial activity of six synthetic short peptides against clinical isolates of methicillin-susceptible and MRSP isolated from infected dogs. All six peptides demonstrated potent antistaphylococcal activity regardless of existing resistance phenotype. The most effective peptides were RRIKA (with modified C terminus to increase amphipathicity and hydrophobicity) and WR-12 (α-helical peptide consisting exclusively of arginine and tryptophan) with minimum inhibitory concentration50 (MIC50) of 1 µM and MIC90 of 2 µM. RR (short anti-inflammatory peptide) and IK8 ‘‘D isoform’’ demonstrated good antimicrobial activity with MIC50 of 4 µM and MIC90 of 8 µM. Penetratin and (KFF)3K (two cell penetrating peptides) were the least effective with MIC50 of 8 µM and MIC90 of 16 µM. Killing kinetics revealed a major advantage of peptides over conventional antibiotics, demonstrating potent bactericidal activity within minutes. Studies with propidium iodide and transmission electron microscopy revealed that peptides damaged the bacterial membrane leading to leakage of cytoplasmic contents and consequently, cell death. A potent synergistic increase in the antibacterial effect of the cell penetrating peptide (KFF)3K was noticed when combined with other peptides and with antibiotics. In addition, all peptides displayed synergistic interactions when combined together. Furthermore, peptides demonstrated good therapeutic indices with minimal toxicity toward mammaliancells. Resistance to peptides did not evolve after 10 passages of S. pseudintermedius at sub-inhibitory concentration. However, the MICs of amikacin and ciprofloxacin increased 32 and 8 fold, respectively; under similar conditions. Taken together, these results support designing of peptide-based therapeutics for combating MRSP infections, particularly for topical application

Antibacterial evaluation of synthetic thiazole compounds in vitro and in vivo in a methicillin-resistant staphylococcus aureus (MRSA) skin infection mouse model

The emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA), including strains resistant to current antibiotics, has contributed to an increase in the number of skin infections reported in humans in recent years. New therapeutic options are needed to counter this public health challenge. The aim of the present study was to examine the potential of thiazole compounds synthesized by our research group to be used topically to treat MRSA skin and wound infections. The broth microdilution method confirmed that the lead thiazole compound and four analogues are capable of inhibiting MRSA growth at concentrations as low as 1.3 μg/mL. Additionally, three compounds exhibited a synergistic relationship when combined with the topical antibiotic mupirocin against MRSA in vitro via the checkerboard assay. Thus the thiazole compounds have potential to be used alone or in combination with mupirocin against MRSA. When tested against human keratinocytes, four derivatives of the lead compound demonstrated an improved toxicity profile (were found to be non-toxic up to a concentration of 20 μg/mL). Utilizing a murine skin infection model, we confirmed that the lead compound and three analogues exhibited potent antimicrobial activity in vivo, with similar capability as the antibiotic mupirocin, as they reduced the burden of MRSA present in skin wounds by more than 90%. Taken altogether, the present study provides important evidence that these thiazole compounds warrant further investigation for development as novel topical antimicrobials to treat MRSA skin infections. © 2015 Mohammad et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Effect of concrete cover thickness and main reinforcement ratio on flexural behavior of RC beams strengthened by NSM-GFRP bars

Experimental and numerical programs were invoked to investigate the effect of concrete cover and area of main steel reinforcement on the flexural behavior of strengthened RC beams by near-surface mounted glass fiber reinforced polymeric (NSM GFRP) bars of different lengths. Nine beams divided into three main groups were tested under four-point bending. The three beams of the first group were strengthened by different lengths of GFRP bars and having a concrete cover of 50 mm, while the three beams in the second group were strengthened in a similar manner as those of the first group but the concrete cover was 30 mm. The main steel reinforcement in the first and second groups was 2Ø10. The three beams of the third group were similar to those of the first and second group but the main steel reinforcement was 2Ø16. The 3-D FE commercial ANSYS program was used for the numerical work. The experimental results showed that decreasing the concrete cover increased the flexural capacity of the strengthened RC beams but this improvement disappeared by decreasing the NSM GFRP bar length. The RC beams flexural strength increased with increasing area of main steel reinforcement. The numerical results showed an agreement with the experimental results