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    Antibacterial activity and essential oil composition of Calendula arvensis L.
    (2020) Servi, Hüseyin; Vatansever, Cansu; Doğan, Ahmet; Majeed, Vanya Ari
    Essential oil composition and antibacterial activity of Calendula arvensis L. were investigated. The essential oil of aerial part was obtained through hydro-distillation using a Clevenger type apparatus with 0.38 (v/w) yield. The essential oil components were determined by GC-MS analyses. Thirty-six components were identified in the essential oil that represented 91.8 % of the oil. The major components of the essential oil were δ-cadinene (14.8 %), epi-cubebol (10.7 %), α-cadinol (8.5 %), cubenol (7.7 %), cubebol (7.2 %), 1-epi-cubenol (5.4 %) and ledene (5.1 %). Antibacterial activity of essential oil was observed against Staphylococcus aureus ATCC 29213, Bacillus cereus ATCC 14579, Pseudomonas aeruginosa ATCC 27853 and Escherichia coli ATCC 25922 by using a broth microdilution. The essential oil showed weak inhibitory activity against E. coli and B. cereus at 8 mg/mL. The oil didn‘t show any antibacterial activity against S. aureus and P. aeruginosa. These results revealed that the oil was rich in oxygenated sesquiterpenes as well as had a weak antimicrobial activity.
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    Antimicrobial Effect of Propolis Drops On Oral Pathogens: AnIn Vitro Study
    (2021) Ozan, Günçe; Eren, Meltem Mert; Vatansever, Cansu
    Background: The aim of this in vitro study was to evaluate theantimicrobial effectiveness of various propolis drops found easilyin Turkey against two oral pathogens; Streptococcus mutans andEnterococcus faecalis. Methods: Seven different propolis drops (Group 1 to 7: UmayHerbal Organic Propolis, Bee'o Up [15%], Propoli EVSP, BrazilianGreen Liquid Propolis, Eğriçayır Propolis, Bee'o Up [30%],Biostore Propolis) were included in the study. Antimicrobial effectof drops was investigated by the agar plate diffusion method. Petridishes were prepared with Brain-Heart Infusion broth. 100 µl ofmicroorganisms and 10 µl of each propolis were planted to thesepetri dishes from a broth culture. Inhibition zones formed on the24th hour were measured in mm's and each experimental groupwas photographed. Data were compared by Mann Whitney-U test. Results: Only water-based propolis of the present study (Group1) formed no inhibition zone against both oral pathogens andalcohol-based groups 4 and 5 formed no zone only against thelatter. Group 5 showed significantly the highest antimicrobial effectagainst S. mutans, however that group showed no influence on E.faecalis. Group 6 was found significantly more effective on E.faecalis than other propolis drops (p<0.05). Conclusion: All of the groups showed antimicrobial effect oneither one of the oral pathogens except for the water-basedpropolis drop. Compared to E. faecalis, tested propolis drops hadaffected S. mutans more. Thus, propolis extracts could be used asa more natural and harmless prevention method to dental cariesspecifically.
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    Comparison of the anti-legionella fill material against standard polypropylene fill material in model cooling tower water system
    (2020) Turetgen, Irfan; Vatansever, Cansu
    Objective: Cooling towers are heat exchangers which are utilized in specific industrial devices. They possess the potential to support Legionella bacteria. The objective was to evaluate the efficacy of biocide impregnated polymer against regular polypropylene polymer in terms of anti-Legionella features during a 120-day period. Materials and Methods: To reduce the bacterial colonization in towers, anti-Legionella splash fill and regular polypropylene splash fill material were tested to compare anti-Legionella activity and biofilm formation potential within a 120-day period using a lab-scale recirculating cooling tower model system. The system was experimentally infected with Legionella suspension and operated continuously for 120 days. Results: Legionella colonization occurred on both test material surfaces beginning at the first month. Legionella counts on surfaces were increased over time on standard polypropylene surfaces. The product with anti-Legionella activity showed significantly lower Legionella colonization in comparison to standard polypropylene fill. Conclusion: The product with anti-Legionella activity has a significant biocidal effect against surface-associated Legionella under the above-mentioned conditions which mimics cooling tower water systems. Product seems to facilitate effective control program criteria against Legionella colonization in cooling towers.
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    Effect of surface sealant on surface roughness and bacterial adhesion of bulk-fill composites
    (Sage Publications Ltd, 2021) Ozan, Günce; Eren, Meltem Mert; Vatansever, Cansu; Erdemir, Uğur
    Surface sealants are reported to ensure surface smoothness and improve the surface quality of composite restorations. These sealants should also reduce the bacterial adhesion on composite surfaces however, there is not much information regarding their performance on bulk-fill composite materials. The aim of this study was to evaluate the effect of surface sealant application on surface roughness and bacterial adhesion of various restorative materials. Disc-shaped samples were prepared from a compomer, a conventional composite and three bulk-fill composites. Specimens of each group were divided into two groups (n = 9): with/without surface sealant (Biscover LV, [BLV]). Surface roughness values were examined by profilometry and two samples of each group were examined for bacterial adhesion on a confocal laser scanning microscope (CLSM). Bacterial counts were calculated by both broth cultivation and microscopic images. Results were analyzed with one-way ANOVA and Bonferroni/Dunn tests. Following the BLV application, there was a decrease in the surface roughness values of all groups however, only Tetric N-Ceram Bulk and Beautifil-Bulk groups showed significantly smoother surfaces (p < 0.001). There were no significant differences among material groups without BLV application. Evaluating bacterial adhesion after BLV application, conventional composite had the lowest values among all followed by the compomer group. Beautifil-Bulk had significantly the highest bacterial adhesion (p < 0.05), followed by Tetric N-Ceram Bulk group. Without BLV application, there was no significant difference among bacterial adhesion values of groups (p > 0.05). CLSM images showed cell viability in groups. Bulk-fill composites showed higher bacterial adhesion than conventional composite and compomer materials. The surface sealant was found to be highly effective in lowering bacterial adhesion, but not so superior in smoothing the surfaces of restorative materials. So, surface sealants could be used on the restorations of patients with high caries risk.
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    Investigating the effects of different physical and chemical stress factors on microbial biofilm
    (Water Research Commission, 2018) Vatansever, Cansu; Türetgen, İrfan
    Microorganisms that adhere to surfaces in order to protect themselves from many adverse environmental conditions form a layer called biofilm. Biofilms protect bacteria from changing environmental conditions such as starvation, antibiotics, disinfectants, pH and temperature fluctuation, dryness and UV rays. In this study, biofilms were formed on surfaces of glass coupons in a cooling tower model system over a period of 180 days. The biofilms were treated with various stress factors monthly. These stress factors were: exposure to temperatures of 4 degrees C and 60 degrees C, pH of 3, 5, and 11, 3 M aqueous NaCl and distilled water, as well as, monochloramine at 2, 500, and 1 000 mg/L (ppm). Following the treatment with stress factors, both the numbers of actively respiring bacteria and the total bacteria in the biofilms were determined by CTC-DAPI staining. The aerobic heterotrophic plate counts (HPC) in the biofilms were determined by the conventional culture method of spread plating on R2A agar. The aim of this study was to determine the impact of these stressors on the model cooling-tower biofilms. Of the stressors tested, those that had the greatest impact were a temperature of 60 degrees C, pH of 3, 3 M NaCl, and monoch lora mi ne at both 500 and 1 000 mg/L. however, when using a non-culture-based viability assay (CTC-DAPI staining), an extremely high number of live bacteria were detected even after applying the most effective stress factors (with the exception of pH 3) of 60 degrees C, 3 M NaCl, monochloramine at 500 and 1 000 mg/L. Results showed that biofilm protects the bacteria from extreme physical and chemical stress conditions. Additionally, the conventional culture technique cannot detect the presence of bacteria that have entered the viable but non-culturable (VBNC) phase; the use of different techniques, such as microscopy and cytometry (flow and solid-phase), is therefore important to obtain more accurate results.
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    Investigation of the effects of various stress factors on biofilms and planktonic bacteria in cooling tower model system
    (Springer, 2021) Vatansever, Cansu; Türetgen, İrfan
    Biofilm is a microbial population which live in a self-produced extracellular polymeric matrix by attaching to surfaces. Biofilms consist of different different types of organisms such as bacteria, fungi, protozoa, etc. Many biofilms that develop in nature consist of more than one type of organism. Biofilms protect bacteria from adverse conditions such as temperature fluctuation and disinfectants. The aim of this study was to determine the effective elimination strategies for combating biofilm and planktonic bacteria in cooling tower model system using different decontamination / disinfection techniques. In this study, 14 week-old biofilms were treated with temperatures of 4 degrees C, 65 degrees C; pH of 3, 11; 2 and 10 mg/l chlorine, 2 and 10 mg/l monochloramine; hypotonic salt (0.01% NaCl) and hypertonic salt (3% NaCl) solution. For enumeration, number of aerobic heterotrophic bacteria was determined by conventional culture method, number of live bacteria was determined by LIVE/DEAD viability kit, CTC-DAPI and Alamar blue staining methods. Temperature of 65 degrees C, pH of 3, 10 mg/l monochloramine and hypertonic salt solution were the most effective parameters for decontamination of biofilm and planktonic bacteria. Biofilm bacteria in the circulating water system were significantly more resistant than planktonic bacteria against stress factors. When the numbers of epifluorescence microscopy and conventional culture technique were compared, significantly higher number of live bacteria were detected using epifluorescence microscopy. Bacteria enter the viable but non-culturable phase by loosing their culturability under stress conditions. For this reason, the conventional culture method should be supported by different techniques to get more realistic numbers.
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    The effect of biofilm inhibitor N-acetylcysteine on the minimum inhibitory concentration of antibiotics used in Gram-negative bacteria in the biofilm developed on catheters
    (2022) Aksoy, Nilay; Vatansever, Cansu; Ersoy, Gizem Zengin; Aksoy, Başak Adaklı; Fışgın, Tunç
    The study determined the effect of N-acetylcysteine (NAC) on the susceptibility of various antibiotics used to treat Gram-negative catheter-related infection in isolates obtained from pediatric patients admitted to the hematology and oncology department of Medical Park Bahçelievler hospital in Istanbul, Turkey. Biofilms were created in vitro utilizing clinical isolates of Escherichia coli, Pseudomonas aeruginosa, Pseudomonas putida, and Proteus mirabilis. 24 h old biofilms were developed on 96-well plate with strains and the minimum biofilm inhibitory concentration (MBIC) of six antibiotics were measured before and after the addition of 75 mg/ml N-acetylcysteine with microplate reader at 450 nm after crystal violet assay. The addition of NAC reduce the MBIC of cefepime, ceftazidime, colistin, meropenem from (16, 16, 8, 4 μg/ml) to (8, 4, 4, 2 μg/ml) respectively in E. coli (isolate 1). In P. aeruginosa (isolate 4), the MBIC of amikacin, ceftazidime, meropenem (64, 32, and 32 μg/ml) reduced to (8, 1, and 0.5 μg/ml) respectively. MBIC of cefepime, colistin, meropenem (32, 16,and 16 μg/ml) reduced to (2, 2,and 0.5 μg/ml) respectively in P. putida (isolate 5). In P. mirabilis (isolate 6), MBIC of amikacin, cefepime, ceftazidime, colisitin and meropenem (64, 128, 32, 4, and 32 μg/ml) reduced to (8, 8, 1, 1, 4 μg/ml). NAC in combination therapy can practically reduce the MBIC of antibiotics used to treat Gram negative bacteria that develop biofilm in medical catheters. As a result, these combinations can be considered as an essential alternative for increasing the antibiotic susceptibility of pathogenic microorganisms and thus increasing treatment success rates.
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    The inhibitory effects of amylase and streptokinase on minimum inhibitory concentration of antibiotics used to treat gram negative bacteria biofilm infection on indwelling devices
    (2023) Aksoy, Nilay; Vatansever, Cansu; Adalı, Ceren; Adaklı Aksoy, Başak; Fışgın, Tunç
    The study evaluated and compared the effect of adding streptokinase and amylase to antibiotics that are already used in clinical practice to treat Gram negative bacteria biofilm infection on indwelling devices on the antibiotics' minimum inhibitory concentration (MIC). 24 h-old biofilms were developed on 96-well plate with eight clinical isolates. MIC of amikacin, cefepime, ceftazidime, colistin, meropenem, and piperacillin–tazobactam, on biofilms were measured before and after the addition of 25 U/ml streptokinase and 25 μg/ml amylase with microplate reader. The addition of streptokinase reduces the MICs of cefepime, ceftazidime, colistin, meropenem from (16, 16, 8, 4 μg/ml) to (8, 1, 1, 0.5 μg/ml) in Escherichia coli (isolate 1). While the addition of amylase reduces the MICs of only cefepime, ceftazidime from (16, 16 μg/ml) to (2, 4 μg/ml) in E. coli (isolate 1). In Pseudomonas aeruginosa (isolate 4), the MICs of amikacin, cefepime, ceftazidime, colistin and meropenem (64, 16, 32, 4, 32 μg/ml) reduced to (2, 1, 0.5, 0.25, 0.5 μg/ml) with streptokinase and (4, 4, 4, 2, 0.5 μg/ml) with amylase respectively. Similar inhibitions were seen in Pseudomonas putida, Proteus mirabilis. We can conclude that the addition of streptokinase and amylase were effective in reducing the MICs of antibiotics that are commonly used to treat Gram negative bacteria biofilm infection on indwelling devices, thereby increasing susceptibility of bacteria to antibiotics. Streptokinase obviously had a greater effect than amylase, implying that it should be prioritized in future in vivo and clinical studies to obtain successful therapy with antibiotics on biofilm infections.