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.     

Interaction of Fibronectin and Aggregation Substance Promotes Adherence of Enterococcus faecalis to Human Colon

This in vitro study investigates the interaction between aggregation substance (AS), a virulence factor of Enterococcus faecalis, and colonic mucosal fibronectin in normal colon and colon from patients with Crohn's disease. Fibronectin was found to be overexpressed in Crohn's disease compared to normal colon. Compared to E. faecalis OG1X:pAM944 (AS-negative), E. faecalis OG1X:pAM721 (expressing AS) showed a significantly enhanced adhesion to human colonic mucosa in normal colon and in colon from patients with Crohn's disease. Double-staining of fibronectin and AS-positive enterococci showed that colocalization of bacteria and fibronectin was significantly more frequent in Crohn's disease than in normal colon. Preincubation of bacteria with soluble fibronectin caused a significant reduction in the adherence to fibronectin. In conclusion, the interaction between AS and fibronectin plays is an important factor that mediates adhesion of Enterococcus faecalis to colonic mucosa. This might be one of the mechanisms responsible for bacterial translocation of Enterococcus faecalis.     

Detection of antibiotic resistant E. coli and Enterococcus spp. in stool of healthy growing children in Portugal

From stool specimens of 118 healthy children's (1–14 years) in Portugal 92 E. coli and 101 Enterococcu s spp. strains have been isolated. Almost half (40.2%) of the E. coli isolates were resistant to ampicillin, 25.0% were resistant to tetracycline and 26.1% were resistant to streptomycin. Resistance genes detected by specific PCR included bla_TEM and/or bla_SHV and/or bla_CTX‐M (33 of 37 ampicillin and/or cefotaxime resistant isolates), tet (A) and/or tet (B) (16 of 23 tetracycline‐resistant isolates), aad A (19 of 24 streptomycin‐resistant isolates), cml A (in the two chloramphenicol‐resistant isolates), aac (3)‐II with/without aac (3)‐IV (in the four gentamicin‐resistant isolates), sul 1 and/or sul 2 and/or sul 3 (in all trimethoprim/sulfamethoxazole resistant isolates). The majority of the resistant E. coli isolates (69.1%) belonged to phylogenetic group B2. Of the enterococci isolates E. faecium (n = 53), E. faecalis (n = 41), E. hirae (n = 4) and E. durans (n = 3) more than one‐fourth (28.7%) of the isolates were resistant to tetracycline; 21.8% were resistant to erythromycin and 8.9% were resistant to kanamycin. Resistance genes detected by PCR in enterococci included aph (3)′‐IIIa (in all kanamycin‐resistant isolates), aac (6′) (in all gentamicin‐resistant isolates), tet (M) and/or tet (L) (26 of 29 tetracycline‐resistant isolates), erm (B) (17 of 22 erythromycin‐resistant isolates). This survey showed that faecal bacteria such as E. coli and enterococci of healthy growing children's could be a reservoir of antimicrobial resistance genes. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

肠球菌属耐药基因检测

目的了解临床分离的肠球菌属抗菌药物耐药基因存在状况。方法采用聚合酶链反应(PCR)检测7种耐药相关基因。结果 20株粪肠球菌中,tetM基因阳性为40.0%,ermB基因为60.0%,aac(6′)/aph(2′)为75.0%,ant(6)-Ⅰ为50.0%,TEM为5.0%,aph(3′)-Ⅲ为50.0%;20株屎肠球菌tetM基因阳性为40.0%,ermB为65.0%,aac(6′)/aph(2′)为90.0%,ant(6)-Ⅰ为70.0%,TEM为25.0%,aph(3′)-Ⅲ为70.0%。结论临床分离的肠球菌属耐药相关基因携带率高,肠球菌属对多种抗菌药物耐药率高,注意消毒隔离。     

肠球菌属医院感染的耐药性分析

目的了解2007-2011年粪肠球菌和屎肠球菌在医院感染中的检出率及对常用抗菌药物的耐药性,指导临床合理用药。方法采用法国生物梅里埃公司全自动细菌鉴定系统VITEK-32型和VITEK Compact进行菌株鉴定,采用GPS110和GP535药敏卡测定其对11种抗菌药物的敏感性。结果 2007年4月-2011年4月医院感染标本中共检出粪肠球菌43株、屎肠球菌50株,50株屎肠球菌主要来自手术切口分泌物、尿液标本,分别占42.0%、16.0%;43株粪肠球菌同样主要来自手术切口分泌物、尿液标本,分别占39.5%、23.3%;屎肠球菌对环丙沙星、青霉素G、左氧氟沙星、氨苄西林耐药率均较高,分别为86.0%、90.0%、74.0%、84.0%,而粪肠球菌分别为53.5%、37.2%、44.2%、27.9%,屎肠球菌对上述抗菌药物的耐药率均高于粪肠球菌,差异有统计学意义(P<0.05);屎肠球菌对万古霉素、替考拉宁、利奈唑胺均敏感;粪肠球菌仅1株对替考拉宁耐药,对万古霉素和利奈唑胺均敏感;4年未检出耐万古霉素肠球菌属。结论粪肠球菌与屎肠球菌在医院感染中的耐药性明显不同,在治疗其引起的感染时应按药敏试验结果用药。     

肠球菌在尿液标本中的分布及其耐药性分析

目的:研究尿液中肠球菌的分布及其耐药性。方法:分析2007年1月-2010年12月尿液标本中分离出的肠球菌分布和耐药性。结果:尿液标本中粪肠球菌较多见,但屎肠球菌和铅黄球菌检出率增高较快。屎肠球菌对青霉素类、呋喃妥因、喹诺酮类、高浓度庆大霉素、高浓度链霉素和利福平的耐药性明显高于粪肠球菌,而对四环素耐药性低于粪肠球菌。结论:尿液中以粪肠球菌为主。肠球菌的耐药性日趋严重,甚至出现了万古霉素耐药肠球菌。