Nanofillers can reduce enamel demineralization without compromising physical properties of the composite. The aim of this study was to evaluate shear bond strength (SBS) and antibacterial effects of an orthodontic composite after adding titanium oxide (TiO2) nanoparticles. Light cure orthodontic composite paste (Transbond XT) was blended with TiO2 nanoparticles. A total of 30 extracted premolars were randomly allocated into two groups of 15. In order to bond brackets, Transbond XT adhesive and nanocomposite were used in each group, respectively. SBS of two groups were determined, and the adhesive remnant index (ARI) scores were assessed. A total of 45 composite discs specimen were prepared. Of the 45 discs, 30 discs were made from nanocomposite and tested for antibacterial properties immediately and 30 days after curing by direct contact test. The antibacterial properties of the remaining 15 discs that were made from the conventional composite were tested immediately after curing as control group. Student's t-test and chi-square tests were used to analyse the data with the significance level of 0.05. No significant difference was found between SBS of conventional and nanocomposites, 24 hours after curing (P = 0.58). Chi-square test showed that ARI scores of two groups were not significantly different after debonding (P = 0.69). Comparison of antibacterial effects between conventional and nanocomposite demonstrated significant difference between two groups, with nanocomposites having a higher antibacterial activity (P = 0.03). Colony count revealed no significant difference in bacterial growth immediately and 30 days after curing in nanocomposite group. Adding TiO2 nanoparticles to orthodontic composite enhances its antibacterial effects without compromising the SBS.
Galbanic acid, a sesquiterpene coumarin from Ferula szowitsiana roots, was investigated for its potentiating effect on the antimicrobial activity of antibiotics as well as ethidium bromide, in 6 multidrug resistance (MDR) clinical isolates of Staphylococcus aureus. Galbanic acid had inhibitory effect on none of the isolated bacteria tested (up to 800 µg /ml). The MIC range of ciprofloxacin, tetracycline and ethidium bromide, against all tested S. aureus were 10-80, 10-80 and 4-16 µg/ml, respectively. These were reduced to 2.5-5, 2.5-5 and 0.5-2 µg/ml in the presence of galbanic acid (300 µg /ml) or verapamil (100 µg /ml). The rate of ethidium bromide (2 µg /ml) accumulation in clinical isolates was enhanced with galbanic acid (300 µg /ml). There is also a decrease in loss of ethidium bromide from bacteria in the presence of galbanic acid. Similar results were obtained when verapamil (100 µg /ml) was used as an efflux pump inhibitor. Galbanic acid, like verapamil, a typical inhibitor of efflux pump, reduced the MIC of ethidium bromide and tested antibiotics. Since efflux is the only known reported mechanism for ethidium bromide resistance, the reduction in ethidium bromide MIC and enhanced accumulation as well as decreased efflux of ethidium bromide in the presence of galbanic acid, can be attributed to this efflux inhibitory properties.
This study was conducted at a 900+ bed general teaching hospital, from May to September 2007, in Iran. The aim of this study was to determine the prevalence of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae and their antimicrobial pattern. The Kirby-Bauer disk diffusion method and the phenotypic disk confirmatory test were performed for each isolate. The total of 206 isolates including 106 E. coli and 100 K. pneumoniae were collected of which 122 isolates (59.2%) were ESBL positive. The prevalence of ESBL-producing strains was 59.2% (122/206). All the isolates were susceptible to imipenem. Among the ESBL-producing isolates, the sensitivity was from 3.3% to 61.5% for ampicillin to aztreonam. From female isolates (136), 59.5% and from male isolates (70), 58.6% were ESBL-producers. Ratios of isolates from hospitalized patients to out-patients were 94/28 in the ESBL-producing group. The number of ESBL-producing isolates according to the isolation sites showed a significant difference between ESBL-producers and non-producers in blood samples (P < 0.05). This study shows that the prevalence of ESBL strains in Iran is high. It seems necessary for clinicians and medical community personnel to be fully aware of ESBL-producing microorganisms.
We applied pulsed-field gel electrophoresis (PFGE) after SmaI digestion and random amplification of polymorphic DNA (RAPD) analysis with nine oligonucleotide primers to 146 blood culture isolates of Staphylococcus epidermidis and 25 blood culture isolates of Staphylococcus haemolyticus. These were obtained over a 12-month period from patients on the neonatal and hematology units of the Central Manchester Health Care Trust. PFGE demonstrated two clusters of isolates of S. epidermidis (type A and type B) on the neonatal ward and a single cluster (type C) on the hematology unit. Type A was represented by 10 indistinguishable isolates from nine patients, type B was represented by 20 isolates from 14 patients, and type C was represented by 26 isolates from 10 patients. Type A isolates were resistant to chloramphenicol and type C isolates were resistant to ciprofloxacin, mirroring current antibiotic usage. There was no evidence of cross infection due to S. haemolyticus. RAPD analysis, on the basis of a single band difference, produced 58 types of S. epidermidis and 12 types of S. haemolyticus with primer 8 (ATG TAA GCT CCT GGG GAT TCA C; 5 to 3) and 54 types of S. epidermidis and 10 types of S. haemolyticus with primer 9 (AAG TAA GTG ACT GGG GTG AGC G; 5 to 3). Combining the results confirmed cross infection. Types A, B, and C were concurrently isolated from the hands of the staff of the appropriate unit. Partial control was achieved by withdrawing ciprofloxacin use in the case of the hematology unit and improving hand hygiene in both units.
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