scholarly journals Effect of Ultraviolet Light Irradiation Combined with Riboflavin on Different Bacterial Pathogens from Ocular Surface Infection

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Jing Shen ◽  
Qingfeng Liang ◽  
Guanyu Su ◽  
Yang Zhang ◽  
Zhiqun Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Uv Light ◽  
Irradiation Time ◽  
Survival Rates ◽  
Experimental Conditions ◽  
Light Power ◽  
Bacteria Growth ◽  
Inhibition Effect ◽  
Staphylococcus Epidermis

In order to study Staphylococcus epidermis and Staphylococcus aureus in vitro viability after the exposure to ultraviolet (UV) light and riboflavin, twelve strains of Staphylococcus epidermis and twelve strains of Staphylococcus aureus were isolated from patients with bacterial keratitis. The growth situation of Staphylococcus epidermidis and Staphylococcus aureus under different experimental conditions was qualitatively observed. The number of colonies surviving bacteria was counted under different UV light power and different exposure time. The experiment showed that there was no inhibition effect on the growth of bacteria using riboflavin alone. In UV alone group and UV-riboflavin group, inhibition effect on the bacteria growth was found. The UV-riboflavin combination had better inhibition effect on bacteria than UV irradiation alone. The amount of bacteria in the UV-riboflavin group was decreased by 99.1%~99.5% and 54.8%~64.6% in the UV alone group, when the UV light power was 10.052 mW/cm2 and the irradiation time was 30 min. Moreover, with the increase of the UV power or irradiation time, the survival rates of bacteria were rapidly reduced. Compared with Staphylococcus aureus, Staphylococcus epidermis was more easily to be killed under the action of UV light combined with riboflavin.

scholarly journals Cationic, anionic and neutral dyes: effects of photosensitizing properties and experimental conditions on the photodynamic inactivation of pathogenic bacteria

2013 ◽  
Vol 11 (4) ◽  
pp. 590-599 ◽  
Author(s):  
Sonia Sabbahi ◽  
Layla Ben Ayed ◽  
Abdellatif Boudabbous
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Irradiation Time ◽  
Chemical Properties ◽  
Neutral Red ◽  
Viable Count ◽  
Photodynamic Inactivation ◽  
Experimental Conditions ◽  
Significant Difference

The aim of this study was to evaluate the photobactericidal effect of four photosensitizers (PSs) with different structural and physico-photochemical properties, namely mesotetracationic porphyrin (T4MPyP), dianionic rose Bengal (RB), monocationic methylene blue (MB) and neutral red (NR). Their photokilling activity was tested in vitro on pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) suspended in nutrient broth (NB) and in phosphate buffered saline (PBS) through following their influence on the PSs antimicrobial efficacy. Photodynamic inactivation (PDI) experiments were performed using visible light (L) and different PSs concentrations (20–70 μM). The ability of these PSs to mediate bacterial photodynamic inactivation was investigated as a function of type of PS and its concentrations, spectral and physico-chemical properties, bacterial strain, irradiation time and suspending medium. Indeed, they showed antibacterial effects against S. aureus and P. aeruginosa with significant difference in potency. Staphylococcus aureus suspended in NB showed 0.92 log units reduction in viable count in the presence of T4MPyP at 20 μM. Changing the suspending medium from NB to PBS, S. aureus was successfully photoinactivated by T4MPyP (20 μM) when suspended in PBS at least time exposure (10 and 30 min), followed by MB and RB.

scholarly journals Photodegradation of some brominated and phenolic micropollutants in raw hospital wastewater with CeO2 and TiO2 nanoparticles

2017 ◽  
Vol 76 (10) ◽  
pp. 2603-2622 ◽  
Author(s):  
Delia Teresa Sponza ◽  
Gökçe Güney
Keyword(s):  
Surface Area ◽  
Uv Light ◽  
Irradiation Time ◽  
Anatase Phase ◽  
Hospital Wastewater ◽  
Nano Tio2 ◽  
Experimental Conditions ◽  
Light Power ◽  
Sequential Treatments ◽  
Average Size

Abstract In this study, the degradations of 2,3,4,5,6-pentabromotoluene (PBT), 2,3,4,5,6-pentabromoethyl benzene (PBEB), triclosan (TCS) and gemfibrozil (GFZ) in raw hospital wastewater were investigated with cerium (IV) oxide and titanium (IV) oxide nanoparticles considering the mechanisms of adsorption, photolysis, and photocatalysis with UV-C lamps. The effects of nano-CeO2 and nano-TiO2 concentrations, irradiation times, UV light powers and hospital wastewater pH on the photodegradation yields of micropollutants namely PBT, PBEB, TCS and GFZ were investigated throughout photocatalysis. The nano-TiO2 produced had an anatase phase with crystalline shape with a surface area of 205 m2 g−1 and an average size of 11.50 nm. The CeO2 nanoparticles had a spherical shape with a higher surface area (302 m2 g−1) than that of TiO2 and a lower average size (8.11 nm). It was found that the removals of PBT, PBEB, TCS and GFZ with adsorption (5.7%–17.1%) and photolysis (9.0%–15.9%) were not significant for both nanoparticles. The photodegradation of PBT (92%), PBEB (90%), TCS (97%) and GFZ (95%) with nano-CeO2 gave better results than nano-TiO2 (90%, 87%, 94% and 93% for PBT, PBEB, TCS and GFZ, respectively) under optimum experimental conditions (0.50 g L−1 nano-CeO2, 45 min irradiation time, 25 °C temperature, pH = 8.50, 210 W UV light power). Both nanoparticles were reused effectively after photo-removals of the micropollutants from the hospital wastewater. The lowest photodegradation yields were 80%, 78%, 75% and 74% for TCS, GFZ, PBT and PBEB, respectively, with nano-TiO2 after six sequential treatments. The lowest photodegradation yields were 86%, 83%, 80% and 79% for the same micropollutants, respectively, with nano-CeO2 after six sequential treatments. The cost to treat 1 m3 raw hospital wastewater were 8.70 € and 2.28 €, for the photocatalytic treatments with nano-TiO2 and nano-CeO2, respectively.

scholarly journals Antimicrobial Activity of Nisin and Lysozyme on Foodborne Pathogens Listeria Monocytogenes, Staphylococcus Aureus, Salmonella Typhimurium, and Escherichia Coli at Different pH

2018 ◽  
Author(s):  
Hamdollah Moshtaghi ◽  
Azadeh Rashidimehr ◽  
Behzad Shareghi
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Listeria Monocytogenes ◽  
Foodborne Pathogens ◽  
Inhibitory Concentration ◽  
Low Ph ◽  
Bacteria Growth ◽  
Microdilution Method ◽  
Natural Preservatives

Background: To prevent or inhibit the growth of pathogenic microorganisms and food spoilage factors, many studies have been done by using natural preservatives. The aim of study was to investigate the effect of different concentrations of lysozyme and Nisin on the growth rate and also to determine the minimum inhibitory concentration (MIC) and minimum bactericidal cocentratiin (MBC) of these combinations on the bacteria of Escherichia coli, Staphylococcus aureus, Salmonella typhimorium and Listeria monocytogenes. Methods: In this study, various concentrations of lysozyme and Nisin were set in form of alone concentration and in combination concentrations (0, 19.53, 39.06, 78.13, 156.25, 312.5, 625, 1250, 2500, 5000) in vitro conditions and 6 pH 5.5, 6, 6.5, 7, 7.5, and 8. Microdilution method at 24°C was done and the combined effect on bacteria growth was read by using ELISA reader. Results: The results showed that lysozyme was less effective on Escherichia coli and Nisin was less effective on Listeria monocytogenes. Moreover, combining lysozyme and Nisin at low pH decreased the MIC. Conclusions: The results of the study showed that the effect of combining lysozyme and Nisin on Staphylococcus aureus is above all other bacteria and at low pH reduces the MIC.

scholarly journals Antimicrobial TEMPO-oxidized hemp fibers with incorporated silver particles

2012 ◽  
Vol 77 (12) ◽  
pp. 1759-1773 ◽  
Author(s):  
Jovana Milanovic ◽  
Tatjana Mihailovic ◽  
Katarina Popovic ◽  
Mirjana Kostic
Keyword(s):  
Staphylococcus Aureus ◽  
Sodium Hypochlorite ◽  
Nitrate Solution ◽  
Catalytic Amount ◽  
Silver Particles ◽  
Experimental Conditions ◽  
Hemp Fibers ◽  
Maximum Sorption Capacity ◽  
Mediated Oxidation

In this paper, the preparation of the antimicrobial silver loaded hemp fibers were carried out by selective TEMPO-mediated oxidation, i.e. oxidation with sodium hypochlorite and catalytic amount of sodium bromide and 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO), followed by silver sorption from aqueous silver nitrate solution. The most suitable experimental conditions for the selective TEMPO-mediated oxidation were determined by changing oxidation conditions: concentration of sodium hypochlorite and duration of sorption. The obtained results showed that the maximum sorption capacity (0.703 mmol of silver per gram of fibers) of modified hemp fibers was obtained for the sample modified with 9.67 mmol NaClO per gram of fibers, during 4 hours. SEM microphotographs of the modified hemp fibers with incorporated silver showed uniformly distributed silver particles on the surface of fibers, with isometric shapes and sizes from 10 to 100 nm, despite the fact that silver was sorbed from ionic solution. The antibacterial activity of the TEMPO-oxidized hemp fibers with silver particles was confirmed in vitro against two strains: Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), and the antifungal activity against fungi Candida albicans (ATCC 24433). The best antimicrobial activity of silver-loaded TEMPO-oxidized hemp fibers was showed against strain Staphylococcus aureus.

scholarly journals Molecular Basis for the Role of Staphylococcus aureus Penicillin Binding Protein 4 in Antimicrobial Resistance

2009 ◽  
Vol 192 (1) ◽  
pp. 134-144 ◽  
Author(s):  
Vikas Navratna ◽  
Savitha Nadig ◽  
Varun Sood ◽  
K. Prasad ◽  
Gayathri Arakere ◽  
...  
Keyword(s):  
New York ◽  
Staphylococcus Aureus ◽  
Antimicrobial Resistance ◽  
Molecular Replacement ◽  
Penicillin Binding Protein ◽  
Experimental Conditions ◽  
Associated Proteins ◽  
Murein Biosynthesis

ABSTRACT Penicillin binding proteins (PBPs) are membrane-associated proteins that catalyze the final step of murein biosynthesis. These proteins function as either transpeptidases or carboxypeptidases and in a few cases demonstrate transglycosylase activity. Both transpeptidase and carboxypeptidase activities of PBPs occur at the d-Ala-d-Ala terminus of a murein precursor containing a disaccharide pentapeptide comprising N-acetylglucosamine and N-acetyl-muramic acid-l-Ala-d-Glu-l-Lys-d-Ala-d-Ala. β-Lactam antibiotics inhibit these enzymes by competing with the pentapeptide precursor for binding to the active site of the enzyme. Here we describe the crystal structure, biochemical characteristics, and expression profile of PBP4, a low-molecular-mass PBP from Staphylococcus aureus strain COL. The crystal structures of PBP4-antibiotic complexes reported here were determined by molecular replacement, using the atomic coordinates deposited by the New York Structural Genomics Consortium. While the pbp4 gene is not essential for the viability of S. aureus, the knockout phenotype of this gene is characterized by a marked reduction in cross-linked muropeptide and increased vancomycin resistance. Unlike other PBPs, we note that expression of PBP4 was not substantially altered under different experimental conditions, nor did it change across representative hospital- or community-associated strains of S. aureus that were examined. In vitro data on purified recombinant S. aureus PBP4 suggest that it is a β-lactamase and is not trapped as an acyl intermediate with β-lactam antibiotics. Put together, the expression analysis and biochemical features of PBP4 provide a framework for understanding the function of this protein in S. aureus and its role in antimicrobial resistance.

scholarly journals Susceptibility Assessment of Methicillin-Resistant Staphylococcus aureus Strains to Lepidium sativum Extract

Dose-Response ◽  
2019 ◽  
Vol 17 (2) ◽  
pp. 155932581985042
Author(s):  
Amna A. Saddiq ◽  
Azza M. Mohamed
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Exposure Period ◽  
Inhibition Zone ◽  
Lepidium Sativum ◽  
Susceptibility Assessment ◽  
Methicillin Resistant ◽  
Bacteria Growth ◽  
Microbial Infections

Many plant-derived compounds have been used to treat microbial infections. Staphylococcus aureus a common cause of many organ infections, has generated increasing concern due to its resistance to antibacterial drugs. This work was carried out to explore the susceptibility of 6 strains (LN872136, LN872137, LN871238, LN871239, LN872140, and LN871241) of methicillin-resistant Staphylococcus aureus to aqueous extract of Lepidium sativum seeds in vitro. Various concentrations (5-20 mg/mL) were used to evaluate the effect of the extract on bacteria growth via the assessment of the microbial biomass and the inhibition zone (IZ). The results showed that the plant extract at 15 or 20 mg/mL, significantly decreased the the biomass of S aureus strains after 24 or 48 hours exposure period. Staphylococcus aureus (LN871241) showed the largest IZ at 20 mg/mL and documented by scanning electron microscope. The current work may suggest that L sativum seed extract can be candidate as a promising antimicrobial agent to treat infection with methicillin-resistant S aureus.

scholarly journals In vitro activity and spectrum of LY333328, a novel glycopeptide derivative.

1997 ◽  
Vol 41 (2) ◽  
pp. 488-493 ◽  
Author(s):  
R N Jones ◽  
M S Barrett ◽  
M E Erwin
Keyword(s):  
Staphylococcus Aureus ◽  
Enterococcus Faecium ◽  
Resistance Mechanisms ◽  
Test Methods ◽  
Species Variation ◽  
Gram Positive ◽  
Gram Negative ◽  
Staphylococcus Epidermis ◽  
Agar Dilution

Reference methods were used to determine the potency of LY333328, a semisynthetic glycopeptide derivative with a key N-alkylation substitution, against 833 strains (393 gram-positive strains and representative gram-negative bacilli) with various defined resistance mechanisms. The MICs at which 90% of the isolates are inhibited (MIC90S) (in micrograms per milliliter) of LY333328 and the percentages of strains at < or = 8 micrograms/ml were as follows: for oxacillin-susceptible Staphylococcus aureus, 2 and 100%, and for oxacillin-resistant Staphylococcus aureus, 4 and 100%; for oxacillin-susceptible Staphylococcus epidermis, 4 and 100%, and for oxacillin-resistant Staphylococcus aureus, 8 and 96%; for Streptococcus serogroups A, B, C, and G, 0.25 to 1 and 100%; for Streptococcus pneumoniae < or = 0.015 to 0.06 and 100%; for Enterococcus faecalis, 2 and 100%; and for vancomycin-susceptible Enterococcus faecium, 0.25 and 100%, and for vancomycin-resistant Enterococcus faecium, 4 and 100%. LY333328 was not active (MIC50, > or = 16 micrograms/ml) against more than 400 representative strains of Enterobacteriaceae, pseudomonads, Acinetobacter spp., Stenotrophomonas maltophilia, Haemophilus influenzae, Moraxella catarrhalis, pathogenic Neisseria spp., and anaerobic gram-negative bacilli. Gram-positive anaerobes were LY333328 susceptible (MICs, < or = 2 micrograms/ml). Test methods and conditions may have affected MICs of LY333328, with most (species variation) agar dilution MICs being greater than the broth microdilution MICs.

Labeling Cells with Silver/Dendrimer Nanocomposites

2004 ◽  
Vol 845 ◽  
Author(s):  
Wojciech Lesniak ◽  
Xiangyang Shi ◽  
Anna Bielinska ◽  
Katarzyna Janczak ◽  
Kai Sun ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Uv Light ◽  
Toxicity Testing ◽  
Water Soluble ◽  
Cell Labeling ◽  
Single Particles ◽  
Experimental Conditions ◽  
Silver Nanocomposite ◽  
Positively Charged

ABSTRACTWe have developed water-soluble, biocompatible, fluorescent, and photostable silver/dendrimer nanocomposites that have a potential to be used for in vitro cell labeling. A PAMAM_E5.NH2 dendrimer was used as a template to prepare first a silver-dendrimer complex in an aqueous solution at biologic pH=7.4. Conversion into nanocomposite was achieved by irradiating the solution of the [(Ag+)25-PAMAM_E5.NH2] complex by UV light to reduce the bound Ag+ to zero-valent Ag0 atoms, which were simultaneously trapped in the dendrimer network. Results indicate that the {(Ag0)25-PAMAM_E5.NH2} silver/dendrimer nanocomposite forms positively charged single particles of 4–5 nm under the experimental conditions used. The dendrimer nanocomposite proved to be fluorescent. Toxicity testing of {(Ag0)25-PAMAM_E5.NH2} nanocomposite revealed a behavior similar to the template dendrimer. Intracellular internalization of the silver nanocomposite and cell labeling capabilities was confirmed by confocal microscopy.

scholarly journals A Highly Active Chimeric Lysin with a Calcium-Enhanced Bactericidal Activity against Staphylococcus aureus In Vitro and In Vivo

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 461
Author(s):  
Xiaohong Li ◽  
Shujuan Wang ◽  
Raphael Nyaruaba ◽  
Huan Liu ◽  
Hang Yang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Catalytic Domain ◽  
Survival Rates ◽  
Intraperitoneal Administration ◽  
Penicillin G ◽  
Bacterial Number ◽  
Cell Wall Binding

Lysins, including chimeric lysins, have recently been explored as novel promising alternatives to failing antibiotics in treating multi-drug resistant (MDR) pathogens, including methicillin-resistant Staphylococcus aureus (MRSA). Herein, by fusing the CHAP (cysteine, histidine-dependent amidohydrolase/peptidase) catalytic domain from the Ply187 lysin with the non-SH3b cell-wall binding domain from the LysSA97 lysin, a new chimeric lysin ClyC was constructed with Ca2+-enhanced bactericidal activity against all S. aureus strains tested, including MRSA. Notably, treating S. aureus with 50 μg/mL of ClyC in the presence of 100 μM Ca2+ lead to a reduction of 9 Log10 (CFU/mL) in viable bacterial number, which was the first time to observe a lysin showing such a high activity. In addition, the effective concentration of ClyC could be decreased dramatically from 12 to 1 μg/mL by combination with 0.3 μg/mL of penicillin G. In a mouse model of S. aureus bacteremia, a single intraperitoneal administration of 0.1 mg/mouse of ClyC significantly improved the survival rates and reduced 2 Log10 (CFU/mL) of the bacterial burdens in the organs of the infected mice. ClyC was also found stable after lyophilization without cryoprotectants. Based on the above observations, ClyC could be a promising candidate against S. aureus infections.

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