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。     

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.     

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.     

肠球菌属生物膜表型和基因型相关性分析

目的了解肠球菌属生物膜形成能力及其毒力基因携带率,分析生物膜的形成能力与毒力基因间的相关性。方法收集复旦大学附属华山医院2015-2017年临床分离自无菌体液的肠球菌属细菌,使用结晶紫染色法测定肠球菌的生物膜形成能力并进行形成能力的强弱分级,采用PCR方法筛查7种常见的肠球菌毒力基因以及Fsr群体感应系统基因(fsrA、fsrB、fsrC)。结果共收集了112株肠球菌菌株,其中粪肠球菌52株,屎肠球菌60株;两者生物膜形成的阳性率分别为63.46%和13.33%,差异具有统计学意义(P<0.001)。52株粪肠球菌毒力基因携带率分别为:esp 40.38%、gelE 69.23%、sprE 73.08%、asa157.69%、cylA 46.15%、cylB 48.08%、cylM 50.00%、fsrA 40.38%、fsrB 42.31%、fsrC 80.77%,携带esp、asa1、cylA、cylB、cylM和fsrB基因的菌株更易形成生物膜。60株屎肠球菌毒力基因携带率分别为:esp 65.00%、gelE 10.00%。结论粪肠球菌比屎肠球菌更容易形成生物膜;多种毒力基因与生物膜形成相关,提示生物膜的形成并不是由单一基因调控,而是由多个基因多系统调控。     

青藏高原藏原羚携带海氏肠球菌的特征研究

目的研究青藏高原野生动物藏原羚携带的海氏肠球菌特征。方法分离细菌,采用16S rRNA、rpoA基因序列比对方法鉴定藏原羚携带的海氏肠球菌。采用K-B纸片法进行药敏试验;使用COGs、SwissProt、CARD和VFDB等数据库对基因组进行分析;采用MUMmer和TreeBest软件构建单核苷酸多态性系统进化树图。结果从15份藏原羚粪便样品分离到2株海氏肠球菌。生化分析、16S rRNA和rpoA基因序列分析支持其为海氏肠球菌的鉴定。基因组分析发现其携带荚膜多糖基因簇。系统进化树分析提示2株藏原羚源海氏肠球菌分别属于不同的进化分支,且都与动物源性菌株进化关系更近。2株菌对多种常用抗生素敏感。结论青藏高原藏原羚携带的病原菌海氏肠球菌基因组中存在荚膜多糖基因簇,利于其抵抗不利环境因素,提示YL69可能具备在人群中传播的潜力。     

体外评估洗必泰根管冲洗即时和7d后对粪肠球菌作用

目的体外实验对比2%洗必泰和其他2种冲洗液对粪肠球菌即时和7d的抗菌能力。方法45个单根管牙根预备,灭菌使用粪肠球菌进行感染。随机分为三组,使用不同冲洗液,取即时和术后七天的微生物样本,计数细菌菌落。结果SPSS统计学分析,2%洗必泰和2.5%次氯酸钠对粪肠球菌有效,7d后洗必泰组呈现更低的CFU计数。结论2%洗必泰是有效的根管冲洗药物,有持续的抗菌能力。     

氨基糖苷类高水平耐药肠球菌医院感染分布特征及耐药性分析

目的:了解氨基糖苷类高水平耐药肠球菌(HLAR)在医院感染中分布特征及耐药现状。方法:常规方法对我院2004～2007年住院患者的各种临床标本进行培养分离,采用全自动微生物鉴定仪对细菌进行鉴定及药敏检测。结果:292株引起医院感染的HLAR中,以粪肠球菌49.3%(144/292)及屎肠球菌41.4%(121/292)为主,分布主要在重症监护室占27.4%(80/292),其次肾内科及神经外科分别为17.5%(51/292)、8.9%(26/292),感染以泌尿系统感染为主占29.8%(87/292)。屎肠球菌对喹诺酮类及β-内酰胺类抗生素的耐药率明显高于粪肠球菌,但粪肠球菌对喹奴普汀/达福普汀的耐药率明显高于屎肠球菌(P<0.05),粪肠球菌及屎肠球菌对万古霉素、替考拉宁均敏感,对力奈唑烷耐药率分别为0.0%及4.1%(5/121)。结论:万古霉素、替考拉宁及力奈唑烷是当前治疗HLAR感染较好的抗菌药物。     

屎肠球菌耐药谱5年动态分析

目的了解我院屎肠球菌检出情况及其对常用抗菌药物的耐药谱动态变化,为临床合理选用抗菌药物提供依据。方法应用回顾性调查方法,对本院从2003年1月～2007年12月间临床样本分离的屎肠球菌的药敏试验进行对比统计分析。结果所分离出的屎肠球菌336株,占肠球菌的40.1%,屎肠球菌对常用抗菌药物呈高度耐药及多重耐药,万古霉素耐药率非常低(0%～1.9%),而替考拉宁则保持100%的敏感性。结论我院屎肠球菌检出率维持在较高水平,万古霉素和替考拉宁可作为经验性治疗屎肠球菌引起的重症感染的首选。     

Triclosan-loaded poloxamine micelles for enhanced topical antibacterial activity against biofilm

Our research group is interested in the study of different technological approaches to treat hospital biofilm as a means to constrain nosocomial-acquired infections. The present work investigated the effect of the incorporation of the antibacterial agent triclosan (TS) into polymeric micelles of poloxamine T1107 (MW=15 kDa, 70 wt% PEO). The aggregation phenomenon was primarily investigated by means of Critical Micellar Concentration in a broad range of pH. Then, the effect of the polymer concentration on the micellar size was evaluated by Dynamic Light Scattering. Solubility levels increased up to 4 orders of magnitude. The drug inclusion affected the micellization, resulting in size increase and micellar fusion. This phenomenon was only apparent in TS-saturated systems. TS-loaded aggregates proved to be active in vitro against a broad spectrum of bacteria but more importantly, also against two representative clinical pathogens: methicilin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VREF). While the former was sensitive to even very low TS levels attainable in poloxamine-free aqueous media, the later was inhibited only when exposed to higher drug levels affordable exclusively using an inclusion system. These findings indicated the release of the drug from the reservoir. Finally, the activity of a TS-containing 5% poloxamine combination of pH 7.4 was assessed on biofilms of Staphylococcus epidermidis. Results showed a significant decrease (p<0.001) in the number of Colony-Formation Units when the biofilm was exposed to the TS/poloxamine as compared to the limited activity of the polymer-free TS control.