Evaluation of the antimicrobial effect of conventional and nanosilver-containing varnishes on oral streptococci

Statement of the Problem: Nanosilver particles have the potential to serve as a bactericidal agent because of the inherent antimicrobial influences of silver ion. The literature confirmed that specific micro-organisms, especially streptococci, have an important role as an etiological factor for caries

Purpose: The aim of this study was to evaluate the antimicrobial effect of conventional and nanosilver-containing varnishes on oral streptococci

Materials and Method: Pure cultivations of Streptococcus mutans and Streptococcus salivarius were prepared on blood agar media. Thereafter, 0.5 McFarland standard of recently grown bacteria in normal saline was prepared and the bacteria were cultivated monotonously on the culture medium surface by applying a swab. Different concentrations of nanosilver varnishes were prepared in the Mueller- Hinton broth medium in the test tubes and equal amounts of 0.5 McFarland suspension of all the tested bacteria were added separately to all test tubes. A tube without varnish was included as the control sample. The tubes were kept at 37°C for 24 hours, then cultured to determine the numbers of bacteria in each tube by counting colonies. The numbers of bacteria in tubes with varnish were compared to the numbers of bacteria in the tube without varnish. In the instance of observing any reduction in the growth, the minimum inhibitory concentration for growth in the tube with varnish was determined

Results: Nanosilver varnish had an antimicrobial effect on S. mutans and S. salivarius. S. salivarius was more susceptible than S. mutans to the nanosilver varnish

Conclusion: Based on the results of this study, nanosilver varnishes can be used under amalgam restorations to reduce microbial population and subsequently preventing the recurrent caries

Identification of bovine, ovine and caprine pure and binary mixtures of raw and heat processed meats using species specific size markers targeting mitochondrial genome

A specific polymerase chain reaction [PCR] method was applied for identification of bovine [Bos taurus], ovine [Ovis aries] and caprine [Capra hircus] pure and binary mixtures of raw and heat-processed meats. These meats are used in food industry products and/or for direct consumption of consumers. The mitochondrial DNA was amplified as a template in a PCR reaction by use of specific primers related to each species. Specific primers with mitochondrial origin amplified amplicons with the length of 300, 172 and 122 bp in target regions in cattle, sheep and goat, respectively. For determination of the primer sensitivity a set of binary meat mixtures with 0.1, 0.5, 1, 5, 10, 50 and 100% based on weight ratio was tested. The detection limit was found to be 0.1% for all samples. In heat-processing program boiled water for 20 min, 121[degree sign]C for 20 and 30 min and 127[degree sign]C for 20 min by autoclaving was used, similar to the conditions that are used in pasteurization, sterilization and also meat processing in industrial factories. The performance of the method was not affected by prolonged heat treatments. The results obtained in the present study confirmed the efficiency of species specific primers for targeting of mitochondrial genome in order to detect bovine, ovine and caprine pure and binary mixtures of raw and heat processed meats with high sensitivity and accuracy

Correlation between nitrogen fixation rate and alginate productivity of an indigenous Azotobacter vinelandii from Iran

Azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gramnegative soil bacterium capable of fixing nitrogen. Oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of A. vinelandii cultivation. This phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. The aim of this study was to design a simple strategy to explain the alginate production, cell growth and nitrogenase activity correlation in A. vinelandii under aerobic conditions. Thirty-five different soil samples were taken from the rhizosphere of agricultural crops of Iran. Enrichment and isolation strategies were employed for microbial isolation. Physiological and biochemical characteristics were determined. Molecular identification was performed using selective nifH-g1 primers. Alginate production and nitrogenase activity assay by each isolate of Azotobacter were carried out. Bacterial growth, alginate production and Nitrogenase activity were conducted by time-coursed quantitative measurements. Total of 26 isolates were selected after enrichment, isolation, and screening. The isolate was identified by molecular tests as A. vinelandii. The highest alginate productions of 1.02 g/l and 0.91g/l were noted after 4 days in 8 isolates, cell biomass of which were estimated 4.88-5.26 g/l. Six of 8 isolates were able to fix atmospheric N[2] on nitrogen-free medium. Rates obtained in isolates were in the range of 12.1 to 326.4 nmol C[2]H[4] h[-1] vial[-1]. Nitrogen fixation and alginate production yielded significant and positive Pearson's correlation coefficient of R[2] = 0.760, p tilde 0.02. Finally association between bacterial growth, alginate production and nitrogenase activity almost noticeable yielded significant and positive Pearson's correlation coefficient R2 = 0.723, p tilde 0.04.

[Laboratory evaluation of the effect of fluoride-releasing fissure sealants on growth of oral Streptococcus]

Nowadays, application of sealants is introduced as the most effective method for prevention of occlusal caries. However, the outcome of the microorganisms that are sealed by dental sealants is important. We evaluated the effect of fluoride-releasing fissure sealants on the growth of oral Streptococcus. Pure cultures of Streptococcus mutans, sanguis and salivarius were prepared. 0.5 McFarland suspension of newly growed bacteria in normal saline was produced and using a swab, an even culture was prepared on the surface of the culture. Then, experimental fissure sealants were separately placed in 6mm diameter holes in the culture. The samples were divided into four groups; namely, plates merely including microorganisms with no changes applied; plates with microorganisms cured for 20 seconds; plates with microorganisms with cured fissure sealants [20 seconds] placed in them; plates with microorganisms and uncured sealants placed in them. After incubation in 37°C, the diameter of absence of microorganism growth was measured with a ruler in each plate. For each microorganism this test was repeated 6 times and finally the data was analyzed with ANOVA test and t-test. The results showed that fluoride-releasing fissure sealant may prevent growth of Streptococuus sanguis and salivarius [p<0.05] and the effect of this fissure sealant in preventing growth of Streptococcus mutans is not significant [p=0.05]. Furthermore, the curing process may increase antibacterial properties of fissure sealants. Clinpro-3M [fluoride releasing] may prevent growth of oral Streptococcus [sanguis, salivarius]

Effects of sub-inhibitory concentrations of essential oils of Mentha spicata and Cumminum cyminum on virulence factors of Pseudomonas aeruginosa

Pseudomonas aeruginosa is one of important opportunistic pathogen, that cases serious infections. It produces many virulence factors, and this bacterium usually is resistance against antimicrobial agents. The aim of this study was evaluate the effects of sub-MICs of essential oils of Mentha spicata and Cumminum cyminum on alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M. Minimal inhibitory concentrations [MIC] of essential oils of Mentha spicata and Cumminum cyminum were determined by macrodilution method. Alginate production, biofilm formation, swimming, twitching and adhesion in the present of sub-MICs [1/2, 1/4 and 1/8 MIC] of essential oils were determined in mucoid P. aeruginosa 8821M and compared with controls. The MICs of essential oils against P. aeruginosa for M. spicata and C. cyminum oils were obtained 16 and 32 micro g/ml respectively. The results show that all oils at 1/2 and 1/4 MICs were significantly reduced all tested virulence factors. At 1/8 MICs, M. spicata had effect just on adhesion but C. cyminum had effect on Alginate production, biofilm formation, swimming and twitching. This study showed that sub-MIC levels of M. spicata and C. cyminum essential oils affected alginate production, biofilm formation, swimming, twitching and adhesion in P. aeruginosa 8821M and it is probable to use of these medicinal plants for treating

effect of essential oil of Matricaria chamomilla L. on biofilm formation of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an important opportunistic pathogen. The mucoid strains of P. aeruginosa produce hyperviscous substances consisting mainly of alginate which have important roles in formation of biofilm. We investigated the effect of essential oil of Matricaria chamomilla L. on biofilm production in P. aeruginosa. P. aeruginosa 8821M was used as standard strain for biofilm production. Antibacterial effects of essential oil of M. chamomilla L. [50% in DMSO] was tested by disk diffusion method. The effect of essential oil on biofilm formation of P. aeruginosa 8821M was evaluated following inoculation of bacteria in LB broth medium containing 0.5, 0.35 and 0.2 microgram/ml of oil which were incubated for 24h at 37°C. The biofilm formation was measured by Fonseca method. Bacteria inoculated and un-inoculated media without oil were used as positive and negative controls, respectively. The results showed that the essential oil did not have any antibacterial effect or reduction in biofilm formation in the presence of 0.35 and 0.2 microg/ml of oil. On the other hand, bacteria biofilm formation was significantly reduced in the presence of 0.5 microg/ml of oil in comparison with positive control. This research showed that the essential oil of Matricaria chamomilla L. had no antibacterial effect, but caused reduced biofilm formation in P. aeruginosa. Biofilm formation is an important virulence factor in mucoid strains and our results may suggest the possible use of essential oil in control of infections caused by P. aeruginosa or other related infections

[Identification of helicobater pylori in sinonasal mucosa of patients with chronic sinusitis]

Helicobacter pylori is a microaerophilic, gram negative, spiral organism. Which plays arole in the development of gastritis, duodenal gastric ulcer, and gastric cancer. Helicobacter pylori normally inhabits the human gastric mucus layer. Previous studies have shown by colonization Helicobacter in dental plaque, saliva, tonsils, adenoids and oral cavity lesions. Sinusitis is the most common hygienic problem in the world and a yearly large part of the budget is spent in the diagnosis and treatment of this problem. There are various theories for possible modes of Helicobacter pylori transmission. Although, there is a relation between colonization of Helicobacter pylori in upper gastrointestinal tract and gastro esophageal reflux. So an investigation to identify the presence of helicobacter pylori in the mucosa of the sinonasal of patients with chronic sinusitis will be needed. In the present study we used the polymerase chain reaction [PCR] and urease test [CLO] to investigate the Helicobacter pylori status of paranasal sinus mucosa specimens, obtained from patients with chronic sinusitis. The present study is designed as case-control. The study was performed on 44 patients who were admitted in the ENT clinic between April 2004 and July 2005.22 patients suffered from chronic sinusitis. All medication in this group had failed. So, these patients were selected for endoscopic surgery of sinus. This group was named the case group [22 patients]. Those who had septal deviation without sinusitis, was named the control group. We obtained two endoscopic biopsy specimens from each side of nasal mucosa of patients. These specimens were studied by the CLO test and PCR for helicobacter pylori. Helicobacter pylori was not detected in the mucosa of sinonasal of patients. According to the present ideas, the presence of helicobacter pylori in the mucosa of sinonasal of patients with chronic sinusitis is of low probability