Drug Carriers Based on Graphene Oxide and Hydrogel: Opportunities and Challenges in Infection Control Tested by Amoxicillin Release

Graphene oxide (GO) was proposed as an efficient carrier of antibiotics. The model drug, amoxicillin (AMOX), was attached to GO using a peptide linker (Leu-Leu-Gly). GO-AMOX was dispersed in a hydrogel to which the enzyme responsible for releasing AMOX from GO was also added. The drug molecules were released by enzymatic hydrolysis of the peptide bond in the linker. As the selected enzyme, bromelain, a plant enzyme, was used. The antibacterial nature of the carrier was determined by its ability to inhibit the growth of the Enterococcus faecalis strain, which is one of the bacterial species responsible for periodontal and root canal diseases. The prepared carrier contained only biocompatible substances, and the confirmation of its lack of cytotoxicity was verified based on the mouse fibrosarcoma cell line WEHI 164. The proposed type of preparation, as a universal carrier of many different antibiotic molecules, can be considered as a suitable solution in the treatment of inflammation in dentistry.     

2016-2017年中国西部肠球菌属细菌耐药性监测

目的 总结2016-2017年中国西部地区临床分离肠球菌属细菌对各类抗菌药物的耐药性。方法 收集西部地区10家医院2016年1月-2017年12月临床分离的肠球菌属细菌,常规方法分离培养鉴定,用药敏纸片法、MIC法或E-test法测定细菌对抗菌药物敏感性,参照2017年CLSI标准判读药敏试验结果。结果 2016-2017年共分离到10959株肠球菌属细菌（非重复株）,主要分离自尿标本(5259株,47.9%),菌种分布为屎肠球菌(6431株,58.3%)、粪肠球菌(3912株,35.7%)、鸟肠球菌(201株,1.8%)、鹑鸡肠球菌(142株,1.3%)、铅黄肠球菌(123株,1.1%)。肠球菌属中鹑鸡肠球菌对万古霉素存在较高耐药率,其他菌种对利奈唑胺、万古霉素、替考拉宁、替加环素敏感率较高,屎肠球菌耐药率较粪肠球菌高。西部地区对万古霉素耐药的肠球菌属细菌检出率为1.1%,各省肠球菌属细菌间对抗菌药物的耐药率存在差异;分离菌株对利奈唑胺、万古霉素呈不同程度耐药。结论 肠球菌属细菌对抗菌药物的耐药情况严重,临床医师应结合具体药敏结果合理使用抗菌药物,并加强对耐药菌株的检测与防控。     

Antibacterial and Anti-biofilm Activity of AH Plus with Chlorhexidine and Cetrimide

Introduction

The use of root canal filling materials with antibacterial activity can be considered beneficial to reduce the remaining microorganisms in the root canal system, where Enterococcus faecalis is often found, and prevent recurrent infection. The aim of this study was to evaluate the antimicrobial activity and capacity for inhibiting E. faecalis biofilm formation of AH Plus, alone and mixed with chlorhexidine (CHX), cetrimide (CTR), and combinations of the two.

Methods

AH Plus alone and mixed with 1% and 2% CHX, 0.1%–0.5% CTR, and combinations of both were tested to assess antimicrobial activity by a modified direct contact test and determine inhibition of E. faecalis biofilm formation at 24 hours. The results were expressed as log₁₀ viable counts. Eradication and inhibition of biofilm formation were understood as no bacterial growth or log₁₀ reduction = 5 with respect to the control (AH Plus alone).

Results

AH Plus + CHX showed a low antimicrobial activity with respect to the control (at 2%, log₁₀ reduction = 1.30). None of the tested concentrations achieved eradication or inhibition of biofilm. AH Plus + CTR showed a direct relationship of concentration-antimicrobial effect, reaching a log₁₀ reduction of 2.92 at 0.5% and inhibition of biofilm formation at 0.2%. With the combination CHX + CTR, lower concentrations were needed for the same effect, and eradication and inhibition of biofilm were achieved.

Conclusions

The addition of CHX, CTR, or some combination of both to AH Plus confers it with bactericidal and anti-biofilm activity against E. faecalis.     

Effective Analysis of the Use of Peracetic Acid after Instrumentation of Root Canals Contaminated with Enterococcus faecalis

Introduction

The aim of this study was to evaluate the effectiveness of peracetic acid (PAA) in cleaning root canals contaminated with Enterococcus faecalis.

Methods

Sixty first and second mandibular molars were used. Their mesiobuccal canals were prepared with the Reciproc System (VDW, Munich, Germany). The canals were irrigated with 10 mL saline during instrumentation. The teeth were randomly divided into 3 groups (n = 20), according to the irrigation solution to be used after instrumentation: group PAA (5 mL 1% PAA), group EDTA/sodium hypochlorite (NaOCl) (5 mL 17% EDTA followed by 5 mL 2.5% sodium hypochlorite), and group S (5 mL saline). Microbiological samples were collected before instrumentation and after final irrigation. Bacterial quantification was performed by counting the number of colony-forming units (CFUs/mL). The results were analyzed by the nonparametric Wilcoxon and Kruskal-Wallis tests.

Results

The 3 groups showed a significant reduction (P < .05) in CFUs/mL after final irrigation. PAA and NaOCl associated with EDTA produced a significantly higher reduction in CFUs/mL (P < .05) compared with saline. There was no statistically significant difference between PAA and EDTA + 2.5% NaOCl (P > .05).

Conclusions

According to the results of the present study, the effectiveness of 1% PAA was similar to that of 17% EDTA + 2.5% NaOCl in cleaning curved root canals contaminated with E. faecalis.     

三代头孢、碳青酶烯类抗生素对肠道内肠球菌影响的机制探讨

目的 探讨三代头孢、碳青酶烯类广谱抗生素对脓毒症大鼠肠道内肠球菌的影响.方法 91只健康SD大鼠随机分为正常对照组、烫伤未治疗组、烫伤头孢曲松3日组及9日组、烫伤亚胺培南3日组及9日组、脓毒症未治疗组、脓毒症头孢曲松3日组及9日组、脓毒症亚胺培南3日组及9日组.采用大鼠背部烫伤模型,烫伤后24h分两次给予内毒素(共20mg/kg)进行"二次打击"."二次打击"24h后分别给予头孢曲松、亚胺培南腹腔注射治疗,在相应时相点分别取大肠内容物行肠球菌定量培养、菌种鉴定.结果 经内毒素"二次打击"的脓毒症大鼠肠道肠球菌数量较正常对照组、烫伤未治疗组显著增多(P＜0.01),并以原优势菌--粪肠球菌增多为主;应用抗生素治疗后大鼠肠道肠球菌数量进一步增多,且屎肠球菌的增长超过了粪肠球菌而成为肠道优势菌群.结论 广谱抗生素使定植于肠道的正常益生菌被大量杀灭,屎肠球菌成为优势菌群,从而造成肠道微生态环境破坏.     

洗必泰葡萄糖酸盐对感染根管细菌生物膜的实验研究

目的：探讨洗必泰葡萄糖酸盐作为根管冲洗药物,对粪肠球菌生物膜的灭菌作用。方法：在无菌盖玻片上制备粪肠球菌生物膜,应用0．2％和5％洗必泰葡萄糖酸盐冲洗,分别作用1min和5min,激光扫描共聚焦显微镜观察灭菌效果。结果：0．2％或5％洗必泰葡萄糖酸盐的灭菌效果随作用时间的延长而增加（P＜0．05）;5％洗必泰葡萄糖酸盐作用1min的灭菌效果明显优于0．2％洗必泰葡萄糖酸盐（P＜0．05）,而其作用5min的灭菌效果与0．2％洗必泰葡萄糖酸盐者无差异（p＞0．05）。结论：洗必泰葡萄糖酸盐具有明显的杀灭粪肠球菌生物膜的作用,其不同浓度和不同作用时间的灭菌效果不同,然而尚不能达到完美的根管冲洗消毒目的。     

饥饿期粪肠球菌生物膜毒力因子明胶酶E表达研究

目的:研究粪肠球菌生物膜形成相关毒力因子明胶酶E(gelE)在饥饿期及药物作用后的表达情况。方法:体外建立对数期、稳定期、饥饿期粪肠球菌生物膜模型,分别以1%、2.5%、5.25%次氯酸钠溶液作用于各时期粪肠球菌生物膜后,用Real-time PCR对gelE的基因表达相对量进行检测。结果:gelE基因表达相对量,饥饿期高于稳定期及对数期(P<0.05);用药后,3个期gelE基因表达相对量,5.25%次氯酸钠溶液组低于2.5%次氯酸钠溶液组和1%次氯酸钠溶液组(P<0.05)。结论:饥饿期粪肠球菌生物膜形成相关毒力因子gelE较对数期及稳定期表达增强。次氯酸钠浓度依赖性可抑制粪肠球菌毒力因子gelE的表达。     

Antibiofilm Effects of Endodontic Sealers Containing Quaternary Ammonium Polyethylenimine Nanoparticles

Introduction

This study evaluated the antibiofilm effects of 2 endodontic sealers incorporated with quaternary ammonium polyethylenimine (QPEI) nanoparticles at a 2% concentration (w/w).

Methods

The materials tested were AH Plus and Pulp Canal Sealer EWT (PCS) in the commercial unmodified form or containing 2% QPEI. Antibiofilm assays were conducted by using direct-contact and membrane-restricted tests for evaluation of bacterial viability in biofilms grown onto membranes or paper disks and the crystal violet microtiter-plate assay to evaluate the effects of sealer extracts on the biofilm biomass. Two Enterococcus faecalis strains (ATCC and an endodontic isolate) were used.

Results

Direct contact and membrane-restricted antibiofilm tests revealed that PCS 2% was the only material to promote total killing of E. faecalis ATCC biofilms. All the materials significantly reduced bacterial counts in E. faecalis ATCC biofilms when compared with the positive control in both tests (P < .05). In the direct test against E. faecalis RW35, PCS 2% was significantly more effective than the other materials and was the only one that showed significantly lower counts than the positive control (P < .05). In the crystal violet assay, only AH Plus 2% presented optical density readings significantly lower than the positive control of the ATCC strain (P < .05). No other significant effects on the biofilm biomass of the 2 E. faecalis strains were observed for any of the sealers tested (P > .05).

Conclusions

Addition of QPEI nanoparticles improved the killing ability of PCS against biofilms of both E. faecalis strains and the effects of AH Plus on the biomass of biofilms from the ATCC strain.