Higher Antibacterial Effect Research Articles

In vitro antimicrobial susceptibility testing of human Brucella melitensis isolates from Ulanqab of Inner Mongolia, China

BackgroundBrucellosis is an endemic disease in the Inner Mongolia Autonomous Region of China and Ulanqab exhibits the highest prevalence of brucellosis in this region. Due to the complex nature of Brucellosis, a cure for this disease has proven to be elusive. Furthermore, the reduced susceptibility of Brucella spp. to antimicrobial agents has been reported as a potential cause of therapeutic failure. However, detailed in vitro antimicrobial susceptibility patterns pertaining to Brucella isolates from this region have not yet been published. The aim of this study was to evaluate the antibiotic susceptibility profile of Brucella melitensis clinical isolates from Ulanqab, Inner Mongolia, China.MethodsA total of 85 B. melitesis isolates were obtained from humans in Ulanqab of Inner Mongolia, China; the antimicrobial susceptibility of 85 clinical isolates to nine antibiotics was assessed using the E-test method according to the CLSI (Clinical and Laboratory Standards Institute) guidelines.ResultsAll of the tested isolates were susceptible to minocycline, sparfloxacin, doxycycline, tetracycline, ciprofloxacin, gentamicin and levofloxacin. Resistance to rifampin and cotrimoxazole was observed in 1.0% (1/85) and 7.0% (6/85) of the isolates, respectively. However, rpoB gene mutations were not observed in single isolates exhibiting resistance to rifampin.ConclusionsWe observed that B. melitensis isolates are susceptible to the majority of the tested antibiotics. Furthermore, minocycline and sparfloxacin exhibited extremely high bactericidal effects in relation to the B. melitensis isolates. The sensitivity of commonly used drugs for the treatment of brucellosis should be regularly monitored. To the best of our knowledge, this is the first report of rifampin and cotrimoxazole resistant isolates of B. melitensis in China. In summary, based on the findings from this study, we suggest that antibiotic administration and use should be rationalized to prevent future drug resistance.

Enzymatic and bactericidal activity of monomeric and dimeric forms of myeloperoxidase

This study was carried out to compare the enzymatic and bactericidal activity of mature, dimeric myeloperoxidase (MPO) and its monomeric form. Dimeric MPO was isolated from HL-60 cells. Hemi-MPO obtained from dimeric MPO by reductive cleavage of a disulfide bond between protomeric subunits was used as the monomeric form. Both peroxidase and halogenating (chlorinating) activities of MPO were assayed, each of them by two methods. Bactericidal activity of the MPO/Н2О2/Cl- system was tested using the Escherichia coli laboratory strain DH5a. No difference in the enzymatic and bactericidal activity between dimeric MPO and hemi-MPO was found. Both forms of the enzyme also did not differ in the resistance to HOCl, the main product of MPO. HOCl caused a dose-dependent decrease in peroxidase and chlorinating activity, and the pattern of this decrease was identical for dimeric MPO and hemi-MPO. At equal heme concentration, a somewhat higher bactericidal effect was observed for the hemi-MPO/Н2О2/Cl- system compared with the dimeric MPO/Н2О2/Cl- system. However, this is most likely not related to some specific property of hemi-MPO and can be accounted for by the higher probability of contacting between bacterial surface and hemi-MPO molecules due to their two-fold greater number relative to that of dimeric MPO molecules at the same heme concentration. By using Western-blotting with antibodies to MPO, we showed, for the first time, that the dimeric molecule of MPO could be cleaved into two monomeric subunits by HOCl, most probably due to oxidation of the disulfide bond between these subunits. This finding suggests that appearance in blood of MPO corresponding in mass to its monomer may result from the damage of dimeric MPO by reactive halogen species, especially upon their overproduction underlying oxidative/halogenative stress in inflammatory diseases.

Effect of ZnO Nanoparticles, Fullerene (C60) and Pyocyanin on Imipenem Resistant Gram Negative Bacteria Isolated from Hospital Environment

The resistance of bacteria from hospital environments has been less frequently investigated. Twenty-seven Gram-negative bacterial isolates were isolated and identify from the hospital environment. The isolates were Acinetobacter baumanii (16 isolates), Pseudomonas aeruginosa (4 isolates), Enterobacter cloacae (3 isolates) Klebsiella pneumoniae (3 isolates) and Escherichia coli (one isolate). Antimicrobial susceptibility test was performed by disk diffusion method and polymerase chain reaction was used to detect blaNDM-1 genes among imipenem-resistant MBL positive isolates. The results showed that the all isolates were imipenem-resistant, cefotaxime resistance was seen in 48.14% of isolates, ciprofoxacin resistance rate was 11.11%, and 25 isolates (92.5%) were inferred to be MBLs producers. Among these isolates, 11 isolates had blaNDM-1 genes. The antibacterial effect of ZnO nanoparticles, fullerene (C60) and pyocyanin against various bacterial isolates from hospital environment was investigated. Preliminary growth analysis data suggest that ZnO nanoparticles and pyocyanin have signifcantly higher antibacterial effects on bacteria than do fullerene (C60). The nanoparticles reduced the growth of A.baumanii and E. cloacae higher than that with P. aeruginosa and K. pneumonia. It was concluded that nanoparticles and pyocyanin have potential as a therapeutic agent against Gram-ve bacteria from the hospital environment.

Preparation and in vitro characterization of silver-doped bioactive glass nanoparticles fabricated using a sol-gel process and modified Stöber method

The study aimed at preparing Ag-doped bioactive glass (BG) nanoparticles containing 5wt% Ag2O using a new modified Stöber method (Ag-BGm) and the conventional sol-gel method (Ag-BGsg). The aim of employing the new Ag-doping mechanism is to implement a relatively short process to incorporate higher concentration of silver (Ag+) ions in an attempt to combine the antibacterial activity of silver with the bioactivity of BG. SEM and TEM micrographs showed that Ag-BGm nanoparticles were mondispersed, and spherical, while Ag-BGsg nanoparticles were formed of highly porous irregular agglomerated particles. A significantly higher silicon, calcium and silver ions release from the Ag-BGsg was evident, as compared to Ag-BGm, in deionized water (DIW). In vitro bioactivity test showed rapid bioactive properties of Ag-BGsg in simulated body fluid (SBF), as compared to Ag-BGm. Both BGs showed antibacterial effect against E. coli O157: H7 wild type strain 93111 and S. aureus ATCC 25923 as evident by the disc diffusion assay, but Ag-BGsg showed significantly higher mean inhibition zone compared to Ag-BGm. It may be concluded that both Ag-BGsg and Ag-BGm has the potential to be used as bone substitute materials with the Ag-BGsg being more promising due to its high bioactivity and antibacterial effect.

Antibacterial Effects of Methanol Extracts of Some Plant Species Belonging to Lamiaceae Family

Species belonging to Lamiaceae family are used as an antibacterial agent among medical plants. The aim of the present study was to determinate the antibacterial effects of the methanolic extracts of some plant species belonging Lamiaceae family which distributed to different ecological conditions in Amasya. The antibacterial effects of Stachys annua , Scutellaria salviifolia and Nepata nuda plant extracts were determined by disc diffusion and micro dilution methods. The antibacterial effects of plant extracts were tested against standard strains of Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 35218, Klebsiella pneumoniae ATCC 70600, Pseudomonas aeruginosa ATCC 27853 and Salmonella enteritidis ATCC 13076. We observed that plant extracts had antibacterial effect when they compared with control group antibiotics. According to the results of disc diffusion method, the highest antibacterial effect was identified in Scutellaria salviifolia , Stachys annua and Nepata nuda , respectively. The microdilution method was studied concentration range from 6.25 - to 50 mg/ml. MICs of the most effective Scutellaria salviifolia plant extract were 12.5 mg/ml for S. aureus , S. enteritidis and E. coli ; 25 mg/ml for K. pneumoniae and P. aeruginosa . The MICs of Stachys annua extract were 12.5 mg/ml for P. aeruginosa , S. enteritidis and E. coli ; 25 mg/ml for S. aureus and 50 mg/ml for K. pneumoniae . MICs of Nepata nuda were 12.5 mg/ml K. pneumonia ; 25 mg/ml for S. aureus ; 50 mg/ml for P. aeruginosa , S. enteritidis and E. coli. This study showed that Scutellaria salviifolia, Stachys annua and Nepata nuda species have in vitro antibacterial activities.

Paediatric laser dentistry. Part 4: Soft tissue laser applications.

Lasers can provide effective soft tissues applications in children. All the wavelengths produce incision and vaporisation of oral tissues, together with a high bactericidal effect. The haemosthatic effect varys according to the wavelength used, and the choice of a visibile, near, medium or far infrared laser allows a better interaction with specific targets, gingiva, mucosa, frenum, or oral pathology.

The Effect of Silica Coatings on the Structural, Magnetic and Antimicrobial Properties of Silver Doped Manganite Magnetic Nanoparticles for Biomedical Applications

Surface modification of magnetic nanoparticles with biocompatible materials is usually required for biomedical applications. La0�80Ag0�15MnO3 (LAMO) magnetic nanoparticles (MNPs) were synthesized by the sol–gel auto combustion synthesis with the nanoparticles subsequently coated with silica. The effect of the coatings on the structural, morphology, magnetic properties, colloidal stability and antimicrobial properties of LAMO nanoparticles were studied using powder X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, zeta potential and vibrating sample magnetometer. The crystalline perovskite structure of LAMO was retained after silica coating but with a reduction in crystallinity. Also, there was a reduction of agglomeration and average crystallite size (48 nm) were the same after silica coating. The zeta potential of the coated sample revealed a considerable high colloidal stability value (−27.70 mV) at physiological pH 7.4. The magnetization values of 26 emu/g and 25 emu/g recorded for bare and coated LAMO samples, respectively show that LAMO MNPs retained its ferromagnetic behaviour after silica coating. Bare and silica coated LAMO gave very high bactericidal effect against S. aureus however, there was no change in the antimicrobial properties of LAMO MNPs with silica coating. These results show that while the silica coating influences greatly the morphology and colloidal stability of LAMO nanoparticles, it had virtually no effect on the crystalline structure and size, magnetization and the antimicrobial properties.

Chitosan/Cyclodextrin/TPP Nanoparticles Loaded with Quercetin as Novel Bacterial Quorum Sensing Inhibitors.

The widespread emergence of antibiotic-resistant bacteria has highlighted the urgent need of alternative therapeutic approaches for human and animal health. Targeting virulence factors that are controlled by bacterial quorum sensing (QS), seems a promising approach. The aims of this study were to generate novel nanoparticles (NPs) composed of chitosan (CS), sulfo-butyl-ether-β-cyclodextrin (Captisol®) and/or pentasodium tripolyphosphate using ionotropic gelation technique, and to evaluate their potential capacity to arrest QS in bacteria. The resulting NPs were in the size range of 250–400 nm with CS70/5 and 330–600 nm with CS70/20, had low polydispersity index (<0.25) and highly positive zeta potential ranging from ζ ~+31 to +40 mV. Quercetin, a hydrophobic model flavonoid, could be incorporated proportionally with increasing amounts of Captisol® in the NPs formualtion, without altering significantly its physicochemical properties. Elemental analysis and FTIR studies revealed that Captisol® and quercetin were effectively integrated into the NPs. These NPs were stable in M9 bacterial medium for 7 h at 37 °C. Further, NPs containing Captisol® seem to prolong the release of associated drug. Bioassays against an E. coli Top 10 QS biosensor revealed that CS70/5 NPs could inhibit QS up to 61.12%, while CS70/20 NPs exhibited high antibacterial effects up to 88.32%. These results suggested that the interaction between NPs and the bacterial membrane could enhance either anti-QS or anti-bacterial activities.

A Comparative Study of the Antibacterial Efficacy of two Natural Irrigating Solutions with Two Different Root Canal Sealers on E-feacalis

This study aimed to: evaluate the antibacterial efficacy of two natural irrigating solutions(Green Tea, and Propolis) with two different root canal sealers (AH Plus sealer,and Total Fill BC Sealer) against E. faecalis. Methods: One hundred single rootedteeth were selected. All root canals were prepared manually to #50 file. Finally theteeth were sterilized by gamma rays. Each root canal was inoculated with 0.5 ml of E.faecalis. Specimens were divided randomly into two main groups (50 specimens each)according to the irrigating solution; A1 (Green Tea), and A2 (Propolis). Each maingroup was divided into two subgroups with (25 specimens each) according to the typeof sealer used B1 (AH Plus sealer), and B2 (TotalFill BC Sealer). The bacterial samplingcounting process was done three times throughout the study. Five specimens fromeach subgroup were examined by SEM for presence or absence of E. faecalis. Results:The highest mean value of bacterial count was found in (Green tea) (6.50x10x10 ±1.29x10x10) while the least mean value of bacterial count was found in (Propolis) (withless antibacterial effect 2x10x10 ± 1.33x10x10) with higher antibacterial effect. Thehighest mean value of bacterial count was found in (AH Plus Sealer) (5.40x10x10 ±2.44x10x10) with less antibacterial effect while the least mean value of bacterial countwas found in (TotalFill BC Sealer) (3.10x10x10 ± 1.54 x10x10) with higher antibacterialeffect. Conclusions: Propolis is an effective intracanal irrigant in eradicating E.faecalis. On other hand TotalFill BC Sealer is more effective in reducing E. faecalis.

Phytochemical screening and antibacterial investigations of crude methanol extracts of &lt;i&gt;Senna didymobotrya&lt;/i&gt; (Fresen.) H. S. Irwin &amp; Barneby

Objective: Senna didymobotrya (African senna, African wild sensitive plant, peanut butter cassia, peanut butter tree, popcorn cassia, popcorn senna or wild senna) is native to East Africa and is widely used as a medicinal plant among many communities in Kenya. The objective of this research was to evaluate the presence of phytochemicals present in the different plant parts and their antibacterial activity. Methodology and results: Leaves, flowers, stem bark, immature pods and root barks were collected from Siaya, Nandi and Nakuru Counties. These were dried and ground. Methanolic crude extracts were in cooperated in nutrient media at 2.5 %, 5 %, 7.5 % and 10 %. Test organisms Staphylococcus aureus and Escherichia coli were inoculated on impregnated media, incubated and observed for colony development. Observation on growth of cultures was made at an interval of 2 days for 8 days. The area under disease progress stairs (AUDPS) was calculated using the derived colony surface areas. Results indicated that all plant parts contained terpenoids, phenols and steroids. The presence of alkaloids and flavonoids varied with the location the plant was collected and the plant part. Growth of S. aureus cultures grown on media impregnated with 2.5% root bark extract and that with 7.5% stem bark extract were completely inhibited (no growth). Media with 10% flower, pods and leaves extract had average reduction of colony sizes from AUDPS 10102 (control) to AUDPS 2475. Growth of E. coli was completely inhibited on media impregnated with 5% root bark extract and 7.5% stem bark extracts. At 10% concentration, the flowers, pods and leaves extract did not result in complete inhibition of colony growth. Conclusions and applications: The present research suggests that S. didymobotrya extracts possessed antibacterial activity against bacterial pathogens thus supporting their folkloric usage, promising a future scope for its use against microbial populations. Methanolic extracts possessing high antibacterial effects should be further investigated for their therapeutic utility. This would be related to the presence of bioactive metabolites, which are soluble in methanol. There is need to explore further the quantities of phytochemicals in the root and stem barks that make them more potent than the other plant parts. The structures of the bioactive metabolites should be examined in future. Keywords: Antibacterial activity, Methanolic extract, Senna didymobotrya , Escherichia coli , Staphylococcus aureus

Photo-irradiated caffeic acid exhibits antimicrobial activity against Streptococcus mutans biofilms via hydroxyl radical formation

An antimicrobial technique based on photo-oxidation of caffeic acid (CA) has recently been developed, but its effect on biofilm-forming bacteria is unknown. The present study aimed to evaluate the effect of photo-irradiated CA against Streptococcus mutans (cariogenic bacteria) biofilm as it relates to hydroxyl radical formation. S. mutans biofilms grown on hydroxyapatite disks were immersed in CA solution (0–2 mg/mL) and irradiated with LED light at wavelengths of 365, 385, and 400 nm and at irradiances of 500, 1000, and 2000 mW/cm2 for 4 min. Biofilm viable bacterial counts were determined by colony counting. The yield of hydroxyl radicals generated by the LED irradiation of CA solution was quantified by electron spin resonance analysis. Of the conditions tested, the highest bactericidal effect, with a > 5-log reduction in viable bacterial counts, was obtained by irradiation of a 1 mg/mL CA solution with 385 nm LED and at an irradiance of 2000 mW/cm2. Hydroxyl radical formation was related to this bactericidal effect. The present study suggests that the antimicrobial technique based on the 385 nm LED irradiation of CA is effective against cariogenic biofilms and can be applied as an adjunctive chemotherapy for dental caries.

Green synthesis of silver nanoparticles impregnated bacterial cellulose-alginate composite film with improved properties

Bacterial cellulose (BC) has attracted more and more attentions as a biomedical material. However, pure BC possesses a poor mechanical strength in a wet state, a weak water swelling ability after drying as well as no antibacterial activity. To resolve this, a kind of novel silver nanoparticles (AgNPs) impregnated bacterial cellulose/calcium alginate (BC/CA) composite film was fabricated for the first time using a new form of BC/CA double-network (DN) film as the template to in situ synthesize AgNPs by a facile method, UV irradiation. This composite realized obvious improvements in both the mechanical property (fracture strength and fracture strain) and the water swelling ability, with values of 2.97, 1.41 and 4.08times, respectively, those of pure BC, as well as a high and prolonged antibacterial effect for more than 48h.

Effect of Sophora flavescens alkaloid on aerobic vaginitis in gel form for local treatment

ObjectiveTo investigate the effect of Sophora flavescens alkaloid (SFA) in gel form on aerobic vaginitis (AV) and the possible mechanism underlying the effects. MethodsAV rat models were prepared by intravaginal inoculation of Escherichia coli and Staphylococcus aureus. SFA gel and placebo gel were intravaginally administered. In vivo antibacterial effects, vaginal microenvironment, vaginal smears, pathological tissues of vaginas, and retention of gel in the vaginal cavity were investigated. ResultsSFA gel had much higher antibacterial effect than placebo gel. SFA gel protected the vaginal mucosa from erosion of bacteria. At the same time, they inhibited the inflammatory responses, exhibiting little leukocytes and parabasal cells. Furthermore, the number of vaginal Lactobacilli remarkably increased following administration of SFA gel. However, the vaginal pH did not recover to the healthy acidic levels after treatment due to the buffering effect of gel. The gel of a fluorescent agent, Cyanine 7, showed very long retention time in the vaginal cavity, up to more than 24 h, much longer than the solutions. ConclusionThe SFA gel is a promising medicine for local treatment of AV with the advantages of anti-bacteria, protection of vaginal mucosa, increase of Lactobacilli, and long retention time in the vaginal cavity.

Synthesis and investigation of antimicrobial activities of nitrofurazone analogues containing hydrazide-hydrazone moiety

In this research we synthesized and tested for in vitro antimicrobial activity 21 nitrofurazone analogues. The compounds we obtained were identified on the basis of 1H NMR and 13C NMR spectroscopy. The in vitro screening of antimicrobial properties of synthesized compounds revealed a wide spectrum of antimicrobial activity. Compounds 28, 29, 32–43, and 45–48 showed very high bactericidal effect towards Staphylococcus spp. ATTC and Bacillus spp. ATTC (MIC=0.002–7.81µg/ml and MBC=0.002–31.25µg/ml). The levels of activity of several compounds were far better than those of nitrofurantoin, ciprofloxacin or cefuroxime.

Phytochemical composition and biological activities of Artemisia quettensis Podlech ethanolic extract

The present study aim to investigate the phytochemical composition, antibacterial, antioxidant and anticancer activities of the ethanolic extract from aerial parts of Artemisia quettensis Podlech. The aerial part of A. quettensis Podlech extract was used for Gas chromatography–mass spectrometry (GC-MS) analysis, antioxidant, antibacterial and anticancer activities. GC/MS analysis of extract from this plant showed 23 major components and the most dominant components were acetic acid, [4-(1-hydroxy-1-methylethyl) cyclohex-1-enyl] methyl ester (13.88%), trans-Phytol (10.06%) and 2,6-Dimethyl-2,6-octadiene-1,8-diol diacetate (6.8%). The extract had significant antibacterial and anticancer effects. The highest percentage of antioxidant activity was 78.46% at 2 mg/mL concentration of extract. Moreover, the highest antibacterial effects of extract were against to gram-positive bacteria and the IC50 cell cytotoxicity value on HT29 cell line in 24 h, 48 h and 72 h were 31.54, 6.08 and 2.96 mg/mL, respectively. From this study, A. quettensis Podlech could be considered as a promising source for novel drug compounds.

Antibacterial Activity of Electrospun Silver Nitrate /Nylon 6 Polymeric Nanofiber Water Filtration Mats

Bacterial water pollution is a genuine general wellbeing concern since it causes various maladies. Antimicrobial nanofibers can be integrated by incorporating nanobiocides, for example, silver nanoparticles into nanofibers. Nylon 6 was dissolved in formic acid at a concentration of (25 wt. %) and tough antibacterial (AgNO3/Nylon) nanofibers were produced utilizing electrospinning system. Polymer solution was tested before accomplishing electrospinning process to acquire its surface tension, electric conductivity and viscosity, where every one of those parameters increased relatively with increasing concentration of (AgNO3) additions. SEM and EDX spectra were utilized to focus on the morphology, surface elemental membrane, fibers and porosize diameters. The resulted nanofiber membrane has an average fiber diameter of 139 nm for pure nylon 6 and 247 nm for (1.2 wt. % AgNO3/Nylon). The resultant polymer membrane was then tested for their ability to destroy microorganisms in water; antimicrobial tests showed that the prepared nanofibers have a high bactericidal effect against Escherichia Coli Bacteria with inhibition zone (10 mm) and antibacterial activity (99%). Likewise, these results highlight the potential utilization of these nanofibrous mats as antimicrobial agents.

New silver(I) complex with diazafluorene based ligand: Synthesis, characterization, investigation of in vitro DNA binding and antimicrobial studies

A novel diazafluorene based complex with silver, [Ag(dian)2]NO3, where dian is N-(4,5-diazafluoren-9-ylidene)aniline, has been prepared and characterized by elemental analysis, IR spectroscopy, 1HNMR, UV–Vis spectroscopy and cyclic voltammetry. In order to explore the relationship between the structure and biological properties, DNA binding propensity and in vitro antibacterial property have also been studied. The mode of DNA-complex interaction has been investigated by electronic absorption titration, luminescence titration, competitive binding experiment, effect of ionic strength, thermodynamic studies, viscometric evaluation, circular dichroism spectroscopy and cyclic voltammetry. The results reveal that the complex binds to CT-DNA in a moderate intercalation capability with the partial insertion of a planar dian ligand between the base stacks of double-stranded DNA with binding constant (Kb) of 2.4 × 105 M−1. The viscosities and CD spectra of the DNA provide strong evidence for the intercalation. An in vitro antibacterial efficacy of the Ag(I) complex on a series of Gram-positive bacteria (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) indicates that the complex exhibits a marked antibacterial activity. The minimum inhibitory concentrations of the complex indicate that it exhibits much higher antibacterial effect on standard bacterial strains of Escherichia coli and Staphylococcus aureus than those of silver nitrate, silver sulfadiazine. The bacterial inhibitions of the silver(I) complex are closely agreed to its DNA binding affinities.

Effectivity of Titanium Oxide Based Nano Particles on E. coli from Clinical Samples.

Nanoparticles composed of Titanium Oxide (TiO2) are non toxic, durable, stable and have a high refractive index with a lot of scope in biomedical applications. Due to their antibacterial effects, they can be applied to inanimate objects like glass, metal and even biomedical implants. This study was conducted to assess the antibacterial effect of Titanium Oxide (TiO2) alone or with Silver (Ag) as an additive on Escherichia coli. Escherichia coli isolates (n=25) sensitive to most of the drugs including first generation cephalosporins, ampicillin and amoxycillin from various samples like pus, urine, sputum and blood were placed onto the glass slides containing TiO2 annealed at 200°C, 400°C, TiO2 with 0.1% Ag as additive, TiO2 with 0.3% Ag, and TiO2 with 0.6% Ag as additive. Samples from this were inoculated at every hour onto sterile petri plates and observed for growth after overnight incubation at 37°C. The organisms which were inoculated onto TiO2 annealed at 200°C showed a slower reduction rate from >1 × 108 cfu/ml to <1 × 10 cfu/ml only after six hours of incubation in visible light. Complete absence of colony forming units was observed after eight hours of incubation. The samples treated with TiO2 at 400°C showed no growth after six hours of incubation itself. Samples treated with TiO2 with increasing gradations of silver as additives showed proportional reduction in the incubation time for the complete absence of colony forming units. Our study shows that pure titanium oxide has a high antibacterial effect on pathogenic samples of Escherichia coli from clinical isolates, which is further increased with the addition of increasing concentrations of silver.

SEM Analysis of Surface Impact on Biofilm Antibiotic Treatment.

The aim of this work was to use scanning electron microscopy (SEM) to investigate the effect of ampicillin treatment on Escherichia coli biofilms formed on two surface materials with different properties, silicone (SIL) and glass (GLA). Epifluorescence microscopy (EM) was initially used to assess biofilm formation and killing efficiency on both surfaces. This technique showed that higher bacterial colonization was obtained in the hydrophobic SIL than in the hydrophilic GLA. It has also shown that higher biofilm inactivation was attained for GLA after the antibiotic treatment (7-log reduction versus 1-log reduction for SIL). Due to its high resolution and magnification, SEM enabled a more detailed analysis of the antibiotic effect on biofilm cells, complementing the killing efficiency information obtained by EM. SEM micrographs revealed that ampicillin-treated cells have an elongated form when compared to untreated cells. Additionally, it has shown that different materials induced different levels of elongation on cells exposed to antibiotic. Biofilms formed on GLA showed a 37% higher elongation than those formed on SIL. Importantly, cell elongation was related to viability since ampicillin had a higher bactericidal effect on GLA-formed biofilms. These findings raise the possibility of using SEM for understanding the efficacy of antimicrobial treatments by observation of biofilm morphology.

Characterization and antibacterial activity of nickel ferrite doped α-alumina nanoparticle

The magnetic behaviour towards biomedical applications of transition metal-ferrite and transition metal-ferrite based nanoparticles is dependent upon the nanoparticles preparation parameters. In this study, an experimental design using central composite design (CCD) has been explored in the production of alumina based nickel-ferrite nanoparticles via wet impregnation method. The effects of operating conditions such as drying temperature, drying time and mass of support on the percentage yield of nickel-ferrite were studied. The optimum nickel-ferrite yield of 97.45% was obtained at 7.5g of α-alumina, drying time of 7h and drying temperature of 116.70°C and then characterized using SEM, EDS and XRD to determine the surface morphology, elemental analysis and crystallinity respectively. The antibacterial activities of the nickel-ferrites doped α-alumina were tested on Gram-negative bacterium: E. coli and Pseudomonas aeruginosa and a Gram-positive bacterium S. aureus. The antibacterial results of the nickel ferrites doped α-alumina nanoparticle on microorganisms showed that the nanoparticles shows no effect on the growth of E. coli but depicts an inhibitory growth on Pseudomonas aeruginosa and S. aureus with high antibacterial effect on S. aureus of 1.70mm diameter of inhibition. Hence, the developed nickel ferrites doped α-alumina nanoparticle shows high antibacterial effect on Pseudomonas aeruginosa and S. aureus which makes it a potential material for biomedical application.