In vitro evaluation of the antibacterial effects of AH26 combined with two different antibiotics on Enterococcus faecalis

Introduction: To prevent growth of residual bacteria, it has been proposed that sealers and filling materials should have antibacterial properties. The aim of this study was to evaluate the antibacterial effects of AH26 sealer combined with two different antibiotics on Enterococcus faecalis. Materials and methods: In this in vitro study, the antimicrobial effects of amoxicillin and minocycline which were added separately to AH26 sealer were evaluated on Enterococcus faecalis. In group 1, 25% amoxicillin with AH26 sealer, in group 2, 25% minocycline with AH26 sealer, in group 3, pure AH26 sealer, and in group 4, distilled water were used. The samples were placed in agar plates inoculated with Enterococcus faecalis. All the plates were incubated for 7 days at 37°C under anaerobic condition, and zones of growth inhibition were measured in millimeters at 24-, 48-, 72- and 7-day intervals. Data were analyzed using 2-way repeated measures ANOVA and multiple comparisons were made by Tukey tests (α=0.05). Results: The results showed that adding antibiotics at 25% concentrations to AH26 sealer created significantly larger zones of growth inhibition compared to the sealer alone (p value < 0.05). In groups 1 and 2, there were significant differences in zones of growth inhibition with an increase in incubation period from 14 to 72 hours; however, there were no significant differences between 72- hour and 1-week intervals. The maximum antibacterial activity was observed in the amoxicillin group. Conclusion: Mixing AH26 sealer with amoxicillin and minocycline significantly increases the antibacterial property of the sealer against Enterococcus faecalis

The role of exopolysaccharides from a chromate reducing Pseudomonas aeruginosa in resistance to hexavalent chromium and antibiotics

زمینه و هدف: کروم شش ظرفیتی (VI) یکی از اکسید کننده های بسیار قوی و جز عناصر سرطان زای گروه A است که در پساب صنایع مختلف وجود دارد. اگزو پلی ساکاریدهای (EPS) ترشح شده توسط باکتری های موجود در این پساب ها می تواند نقش موثری در افزایش مقاومت باکتری ها به این عامل نامساعد ایفا نماید. این تحقیق با هدف بررسی نقش EPS باکتری های مقاوم به کرومات در احیای کروم VI و مقاومت آنتی بیوتیکی آن ها صورت گرفته است. روش بررسی: این مطالعه مقطعی- آزمایشگاهی بر روی باکتری های مقاوم به کرومات موجود در انواع مختلف پساب صورت گرفت. حداکثر غلظت قابل تحمل کرومات (MTC)، مقدار ترشح EPS، احیای کرومات توسط EPS و مقاومت آنتی بیوتیکی جدایه انتخابی به روش کیربی- بائر تعیین گردید. یافته ها: جدایه موثر که واجد بالاترین MTC ( mM128) و حداکثر توان ترشح EPS ( mg.ml-1117/0) بود، بر اساس نتایج تست های بیوشیمیایی گونه ای از سودوموناس آئروژینوزا تشخیص داده شد. مقایسه راندمان 61 درصدی احیای کرومات توسط EPS با راندمان 78 درصدی احیای سلولی کرومات حاکی از نقش قابل توجه EPS در احیای کرومات بود. این باکتری به طیف وسیعی از آنتی بیوتیک ها نیز مقاومت نشان داد. نتیجه گیری: افزایش کروم VI در محیط منجر به افزایش مقاومت باکتری ها با به کارگیری انواع مکانیسم های سازشی چون افزایش ترشح EPS می گردد و به موازات آن مقاومت آنتی بیوتیکی نیز افزایش می یابد. این مقاومت توام از لحاظ پزشکی بسیار مهم بوده و می تواند اطلاعات ارزشمندی در ارتباط با مکانیسم مقاومت آنتی بیوتیکی، ژنتیک پلاسمید و اکولوژی جدایه مورد نظر در اختیار ما قرار دهد

The comparison of antibacterial effect of propolis , sodium hypochlorite 5.25%, and chlorhexidine 2% as intracanal irrigants against enterococcus faecalis: an ex vivo study

Introduction: Debridement of root canal using appropriately safe and effective irrigants is the key factor for long-term success. Purpose of this study was to compare the antibacterial effect of propolis with 5.25% sodium hypochlorite, and 2% chlorhexidine against enterococcus faecalis. Materials &Methods: In this study, 36 single-canal roots were used. The crown was removed and instrumentation was prepared by step-back technique, then teeth were sterilized and contaminated with E. Faecalis, and divided into four groups with 9 cases: group1: Propolis, group2: 5.25% sodium hypochlorite, group3: 2% chlorhexidine and group4: controls. Irrigants were injected by a 27-gauge syringe and roots were incubated in 37°C for one week. Sampling was done and inoculated to tryptone soy broth media, after 24 hours the turbidity was measured. Samples were also cultured on agar plates, and colony-forming units were counted as CFU/ml. Data were analysed using the Mann-Whitney test. Results: The difference between propolis with mean value of 246.77 colonies and chlorhexidine with mean value of zero colonies, was significant (P=.002). Similarly, the difference between chlorhexidine and sodium hypochlorite with mean value 203.55 of colonies was significant and they had significant difference in turbidity (P=.002), too. No significant difference was observed between propolis and sodium hypochlorite with regard to the induced colonies (P=0.781) and their turbidity (P=0.495). Conclusion: It can be concluded that antibacterial activity of 2% chlorhexidine against E. faecalis is more obvious than propolis or 5.25% sodium hypochlorite. But antibacterial activity of propolis over 5.25% sodium hypochlorite or vice versa was not confirmed