抗菌聚氯乙烯材料的制备及性能研究

采用熔融挤出制备抗菌聚氯乙烯复合材料,研究了载银玻璃、载银磷酸锆抗菌剂对PVC材料的抗菌性能、力学性能、透明度的影响,以及抗菌剂在PVC的分散情况。结果表明．抗菌剂均匀分散在PVC基体中：PVC／载银玻璃（PVC-G）对大肠杆菌、金黄色葡萄球菌的抗菌性能高于PVC／载银磷酸锆（PVC-P）,抗菌率高于99O％：抗菌剂的加入对PVC的力学性能影响不大．但使PVC的透明度有所下降,特别是PVC-P的透光率下降了283％。     

载银磷酸锆纱布对烧伤创面常见细菌作用的实验研究

目的 了解载银磷酸锆纱布对烧伤大鼠创面感染常见细菌的抗菌效力。方法制作Wistar大鼠烫伤(以下称烧伤)感染模型，采用试管双倍稀释法测定载银磷酸锆及磺胺嘧啶银的最低抑菌浓度(MIC)及最低杀菌浓度(MBC)。观察大鼠创面用磺胺嘧啶银纱布、普通尢菌纱布、载银磷酸锆纱布(小水洗及水洗20次)后痂下组织的细菌计数和对创面愈合的作用。结果载银磷酸锆对金黄色葡萄球菌、铜绿假单胞菌、大肠竹菌的MIC各为8、8、16mg／L，MBC各为16、8、32mg／L，为磺胺嘧啶银的2～8倍?大鼠创面用未水洗的载银磷酸锆纱布覆盖后，痂下细菌计数比用磺胺嘧啶银纱布低91％，比普通无菌纱布低99％未水洗的载银磷酸锆纱布对创面愈合的作用明显优于其他两种纱布，且其痂下组织细菌计数与水洗20次的效银磷酸锆纱布比较，差异无显著性意义(P＞0．05)。结论载银磷酸锆埘烧伤创面感染常见细菌有较强的抑制和杀灭作用，其敷料可作为治疗措施中新的选择。     

新型消毒溶液IMPRESEPT对印模材料尺寸稳定性的影响

目的:研究新型浸泡消毒剂(IMPRESEPT)浸泡后,对藻酸盐、硅橡胶和聚醚精细印模材料尺寸稳定性的影响,为临床应用提供依据。方法:用60mm×10mm×10mm金属试件制取印模,在IMPRESEPT消毒溶液中分别浸泡10min、20min、30min。用读数显微镜测量浸泡后各时段印模材料的线性长度。结果:除硅橡胶外,藻酸盐及聚醚印模材料在使用IMPRESEPT消毒溶液浸泡前的体积与浸泡后各时段都有显著的统计学差异(P<0.05)。但在30min浸泡时间内,藻酸盐及聚醚印模材料在使用IMPRESEPT消毒溶液浸泡消毒后不会对活动修复体或固定修复体的精确度造成显著影响。结论:新型消毒溶液(IMPRESEPT)在有效浸泡消毒时间内不会影响印模材料的尺寸稳定性,可试用于临床印模的浸泡消毒。     

载银与载庆大霉素硅灰石涂层体外抗菌性能的对比研究

目的 制备具有长效药物缓释效果的骨科抗菌植入材料表面涂层.方法 采用等离子体喷涂技术在钛合金表面沉积硅灰石涂层.一组试样在浓度为重量百分率5%的硝酸银溶液中浸泡24 h获得载银硅灰石涂层,另一组试样通过与装载庆大霉素的胶原溶液发生接枝反应制得载庆大霉素硅灰石涂层.两种涂层的性能通过抗菌剂体外溶液释放实验、抗会黄色葡萄球菌的抑菌环实验和成骨细胞接触培养毒性实验进行表征.结果 成功制备载银与载庆大霉素硅灰石涂层.载银硅灰石涂层均匀释放银离子达50 d;涂层抗金黄色葡萄球菌能力可维持40 d以上.载庆大霉素硅灰石涂层呈爆发性释放庆大霉素,涂层抗会黄色葡葡球菌能力可以维持18 d.两种涂层均不影响成骨细胞在其表面的黏附、增殖以及碱性磷酸酶活性的表达.结论 载银硅灰石涂层与载庆大霉素硅厌石涂层相比,抗菌剂释放较均匀、抗菌时效较长,更具临床应用前景.     

无机抗菌剂的添加对新型自酸蚀处理剂黏结性能和颜色稳定性的影响

目的:测试无机抗菌剂的添加对新型自酸蚀处理剂ESP黏结性能和颜色稳定性的影响。方法:6种无机抗菌剂分别加入ESP中,测试牛牙釉质粘结强度、边缘封闭性以及粘结样本颜色稳定性的变化。结果:抗菌剂添加比为0.5%对ESP牙釉质剪切强度无不利影响(P>0.05),比例增至2.5%时,黏结强度呈不同程度降低。抗菌剂添加比为0.5%时,仅有一种抗菌剂的添加使冠方微渗漏指数较对照组显著增加(P<0.05)。粘结样本经不同处理以老化1年后颜色参数变化最为显著,但与ESP空白对照相比,抗菌剂添加后的颜色变化仍在临床可接受的范围之内。结论:控制适当的添加比例,5种受试的无机抗菌剂的添加对ESP的黏结性能可无显著影响,对颜色稳定性的影响在临床可接受的范围之内。     

间充质干细胞在藻酸盐微球溶液中增殖和分化的实验研究

[目的]探讨藻酸盐微球作为缓释材料在骨组织工程中对种子细胞的增殖和分化的影响。[方法]制成不同浓度的藻酸盐微球溶液，将间充质干细胞接种于其中，观察其生长和增殖情况；置换成骨诱导培养基后，通过检测细胞内碱性磷酸酶的量以及细胞外钙基质分泌来评价间充质干细胞的分化情况。[结果]不同浓度的藻酸盐微球溶液对间充质干细胞的增殖影响不同，随着浓度的增高间充质干细胞的增殖越受抑制，浓度达到10g／L时不适合细胞生长；在成骨诱导培养基中，藻酸盐可以促进细胞内碱性磷酸酶合成量的增加，并表现剂量依赖性，即藻酸盐浓度越高效应越明显，生长在藻酸盐溶液中的间充质干细胞分化为成骨细胞并分泌细胞外钙基质。[结论]一定剂量的藻酸盐微球溶液对间充质干细胞的增殖影响很小，且可促进细胞内成骨活性分子的合成，适于作为骨组织工程的缓释材料。     

载银纳米抗菌复合骨填充材料体外抗菌性能及生物相容性研究

[目的]探讨载银纳米抗菌复合骨填充材料其体外抗菌性能及生物相容性。[方法]采用抑菌环试验、菌落数试验检测材料对金黄色葡萄球菌及大肠杆菌的体外抗菌效果,采用扫描电镜观察材料对金黄色葡萄球菌及大肠杆菌的抗粘附效果。并采用MTT法检测细胞毒性及急性溶血实验评价载银纳米抗菌复合骨填充材料的生物相容性。[结果]抑菌环试验显示第1 d时载银纳米抗菌复合骨填充材料对金黄色葡萄球菌和大肠杆菌的抑菌环直径均最大,分别为(23.6±1.14)mm和(18.8±0.84)mm,随后抑菌环直径随时间延长而缩小,抑菌环在金黄色葡萄球菌和大肠杆菌中的持续时间分别为33、24 d;菌落数试验显示细菌与载银纳米抗菌复合骨填充材料接触24 h后,对金黄色葡萄球菌和大肠杆菌的抗菌率分别为94.18%和85.96%;扫描电镜发现实验组材料表面黏附的细菌明显少于对照组。MTT法测定示载银纳米抗菌复合骨填充材料毒性分级为1级,急性溶血实验示载银纳米抗菌复合骨填充材料溶血率为0.28%。[结论]载银纳米抗菌复合骨填充材料有良好的生物相容性,对金黄色葡萄球菌及大肠杆菌有明显抗菌作用,无明显细胞毒性和红细胞破坏性。     

骨组织工程研究中的美学考量

目的：分别以珊瑚羟基磷灰石(CHA)、藻酸钙为成骨细胞载体，观察裸鼠体内的构建特定形态和可注射组织工程骨的可行性。方法：取兔髂骨，获取骨髓基质干细胞，经体外扩增培养诱导后，获得骨髓基质成骨细胞，分别与CHA和藻酸盐复合，植入和注射于裸鼠背部皮下，6、8周后进行大体观察、组织学和X线检查，观察软骨和骨的形成。以单纯CHA和藻酸盐植入作为对照。结果：植入CHA／成骨细胞组和注射藻酸盐/成骨细胞复合物组均有骨样组织形成，具备骨髓腔样结构，而对照组无骨形成。结论：CHA和藻酸盐均是较好的骨组织工程支架材料，复合成骨细胞后可构建特定形态和可注射组织工程骨。     

不同消毒方法对口腔琼脂藻酸钾印模精度的影响

目的探讨藻酸钾印模和琼脂藻酸钾联合印模对2%戊二醛、1%“84“消毒剂浸泡不同时间或喷涂处理后其尺寸精度的变化.方法分别用藻酸钾、琼脂印模材料对标准试件制取45个印模,分9组,各组5个印模.分别采用清水处理(为对照组),2%戊二醛、1%“84“消毒剂喷涂(为喷涂组),用上述消毒液浸泡10、20、30min(为浸泡组),用超硬石膏灌模,静止2 h后螺旋测位器测量模型.结果对照组分别与相应印模材料消毒的喷涂组比较,差异无显著性意义(均P＞0.05);藻酸钾和琼脂藻酸钾印模材料浸泡的各时段组比较,差异有显著性意义(均P＜0.01),且随着时间的增加其尺寸变化呈正相关;两种消毒液浸泡消毒对两种印模材料精度的影响比较,差异无显著性意义(均P＞0.05).结论2%戊二醛、1%“84“消毒剂浸泡消毒印模10 min最为理想,20 min以内不影响修复体制作的精度,可用于临床.     

复方中药消毒剂消毒藻酸盐印模的应用价值

目的 探究复方中药消毒剂消毒藻酸盐印模的应用价值。方法 用制备好的个别托盘制取藻酸盐印 模,将印模分别放入浓度为108个/ml的金黄色葡萄球菌、白色念珠菌、大肠杆菌的菌悬液中浸泡染菌,再 将染菌后的藻酸盐印模分别浸泡于浓度0.25%、0.50%的亿人安消毒液、2000 mg/L的84消毒液中,分别浸 泡3、5、10、15 min。将消毒后的印模放入100 ml的0.90%生理盐水中浸泡3 min后取出,用倾注培养法对活 菌培养,并进行活菌计数。结果 3种消毒液在作用10 min与15 min时对金黄色葡萄球菌、白色念珠菌、大 肠杆菌的灭菌率为100.00%;在3 min与5 min时两种浓度的亿人安消毒液的灭菌率为97.62%~98.61%,84消 毒液的灭菌率为99.43%~99.64%。结论 0.25%浓度以上的亿人安消毒液浸泡藻酸盐印模10分钟以上对金黄 色葡萄球菌、白色念珠菌、大肠杆菌的灭菌率达到100.00%。     

Silver-containing alginate fibres and dressings

Silver is a broad-spectrum antimicrobial agent that is gaining more and more importance in the wound-management industry. By incorporating silver ions into alginate fibres, highly absorbent alginate wound dressings with antimicrobial properties can be made. Laboratory studies have shown that by incorporating fine particles of silver sodium hydrogen zirconium phosphate, the silver-containing alginate fibres can maintain the white physical appearances while providing a sustained release of silver ions when in contact with wound exudates. Test results have proven that these fibres are highly effective against bacteria.     

The antimicrobial efficacy of a silver alginate dressing against a broad spectrum of clinically relevant wound isolates

Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-11·5 mm. All meticillin-resistant Staphylococcus aureus (MRSA) strains were found to be sensitive to the silver alginate dressing with a CZOI range calculated at 3-7·8 mm. Sensitivity to the silver alginate dressing was also evident for S. aureus and vancomycin-resistant Enterococci. CZOIs of 4·25 mm were calculated for Enterococcus faecium and 9·8 mm for viridans streptococcus. The bacteria which demonstrated the highest tolerance to ionic silver included Enterobacter cloacae and Acinetobacter baumannii. Contrary to this the most responsive microorganisms to ionic silver included strains of staphylococci, viridans streptococcus and Candida albicans. No antibiotic-resistant isolates, as identified by Kirby Bauer Clinical Laboratory Standards Institute classification system, were found to be resistant to ionic silver. When a selected number of microorganisms were grown in the biofilm phenotypic state enhanced tolerance to silver was observed, compared to their non biofilm counterparts. Overall, this study has demonstrated the broad antimicrobial activity of a silver alginate dressing on wound isolates grown in the non biofilm and biofilm state. This finding is clinically relevant as both the non biofilm and biofilm phenotypic states of microorganisms are evident in wounds and therefore significant to delayed healing. Consequently, it is imperative that antimicrobial wound dressings demonstrate antimicrobial activity against microorganisms in both phenotypic states.     

In vitro measurement of antibacterial activities of topical antibacterial creams]

A new method of in vitro measurement of antibacterial activity of different antimicrobial creams is introduced in this paper. The tested cream in known quantity is uniformed suspended in a solid medium, and bacteria of known quantity are inoculated. The result is expressed in MIC. In this observation, four creams were tested against 3 bacteria. It is the authors impression that the new method is better than the traditional disc method, as it reflects better the actual antibacterial activity of the drug in a cream base. It is helpful in selecting an effective drug or to evaluate the effectiveness of certain drugs in clinical practice.     

Antimicrobial Activities of Iodinated Polystyrene Derivatives

Abstract: The antimicrobial activities of insoluble haloge-nated acetamidomethyl-styrene polymers (prepared by covalent bonding of iodine to polystyrene) were assessed as were the factors determining antimicrobial efficacy. The most active materials were selected from chlorinated or iodinated polymers. Antimicrobial activities were assessed for Escherichia coli (ATCC 25922; American Type Culture Collection, Rockville, MD, U.S.A.), Saccharo-myces cerevisiae , and Candida albicans by determining time-course changes in microbial counts in vitro. A 2-iodoacetamidomethylstyrene polymer (No.6-I:-CH₂I) was found to have the greatest antimicrobial activity against both bacteria and fungi. No.6-1 is the first antimicrobial material that did not make an inhibition hollow in the conventional diffusion test or for which conjugated iodine showed antibacterial activity. This material can be introduced into styrene units on the surface of devices by chemical modification. This material was most active at 37^oC. For coated dishes, antimicrobial activity depended on the depth or swollen character of the reactive layer. No.6-1 requires not only a minimum width of polymer layer, but also frequent contact with microbes to have an antimicrobial effect. No.6-1 is valuable as a new material because it has strong antimicrobial activity by itself but does not release active iodine. This material is expected to have various applications in implantable clinical devices.     

In vitro susceptibility of upper respiratory tract pathogens to 13 oral antimicrobial agents

An in vitro comparison of the activities of 13 oral antimicrobial agents against clinical isolates of bacteria commonly responsible for causing upper respiratory tract infections was performed. With regard to Haemophilus influenzae, beta-lactamase-negative strains were susceptible to amoxycillin, augmentin, cefaclor, erythromycin, trimethoprim, cotrimoxazole and tetracycline, with CL 284,635 being the most active agent. With the exception of amoxycillin these drugs were also active against beta-lactamase-producing strains. CL 284,635 was also very active against Branhamella catarrhalis isolates, including beta-lactamase-producing strains, but was less active against the Gram-positive bacteria tested. Cefadroxil, cephradine and cephalexin were mainly active against Gram-positive pathogens. Based on minimum inhibitory concentration determinations, cefaclor, augmentin and co-trimoxazole would be appropriate drugs for the treatment of those cases of otitis media and sinusitis where H. influenzae and Streptococcus pneumoniae are important pathogens provided they are susceptible to these agents.     

Meropenem activity against staphylococci

Meropenem is a new carbapenem with excellent activity against different Gram-negative and Gram-positive bacteria. Its good antibacterial activity is closely related to high hydrolysis resistance by bacterial beta-lactamases. The aim of this study was to evaluate antimicrobial activity of meropenem by comparison that of oxacillin, gentamicin, clarithromycin and ciprofloxacin against 458 staphylococci collected during 2004 period from healthy individuals. Minimum inhibitory concentrations were determined by agar dilution technique. Meropenem has an activity clearly superior to the other tested agents. Resistance rate is zero for all investigated strains.     

In vitro activity of ertapenem against staphylococci

Ertapenem is a new carbapenem with an excellent activity against different Gram-negative and Gram-positive bacteria. Its good antibacterial activity is closely related to high hydrolysis resistance by bacterial beta-lactamases. MATERIAL AND METHOD: We evaluated antimicrobial activity of ertapenem by comparison that of methicillin, gatifloxacin, cefepime and linezolid against 455 staphylococci collected during 2006-2007 period from healthy individuals. RESULTS: Minimum inhibitory concentrations were determined by agar dilution technique. Ertapenem has an activity comparable to the other tested agents. Resistance rate was 1% for all investigated strains.     

Activity of antimicrobial-impregnated silicone tissue expanders

Because bacterial colonization of medical devices may result in clinical infection, it is conceivable that antimicrobial impregnation of tissue expanders may reduce the rate of infection. The objective of this in vitro study was to examine the spectrum, durability, and shelf-life antimicrobial activity of minocycline/rifampin-impregnated silicone tissue expander shells. The impregnated devices exhibited zones of inhibition at baseline against Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli. The impregnated devices exhibited strong residual activity against S. epidermidis and S. aureus after suspension in serum at 37 degrees C for 4 weeks. There was no significant decrease in the size of zones of inhibition after storing the impregnated devices at room temperature for 1 year. These results indicate that minocycline/rifampin-impregnated tissue expander shells provide broad-spectrum and durable antimicrobial activity and that the shelf-life antimicrobial activity exceeds 1 year. These findings prompt future exploration of the anti-infective efficacy of these antimicrobial-impregnated devices.     

Comparative in vitro study on cytotoxicity, antimicrobial activity, and binding capacity for pathophysiological factors in chronic wounds of alginate and silver-containing alginate

Chronic wounds contain elevated levels of proteases, proinflammatory cytokines, and free radicals. The presence of bacteria further exaggerates the tissue-damaging processes. For successful treatment, the wound dressing needs to manage wound exudates, create a moist environment, inhibit infection, bind pathophysiological factors that are detrimental to wound healing, and provide thermal isolation. Furthermore, it has to relieve pain, be easy to use, show no allergic potency, and not release toxic residues. The present study suggests a comprehensive in vitro approach to enable the assessment of wound dressings to support optimal conditions for wound healing. Three alginate-based wound dressings: alginate alone, alginate containing ionic silver, and alginate with nanocrystalline silver, were tested for biocompatibility, antimicrobial activity, and influence on chronic wound parameters such as elastase, matrix metalloproteases-2, tumor necrosis factor-α, interleukin-8, and free radical formation. Alginate was found to bind considerable amounts of elastase, reduce the concentration of proinflammatory cytokines and inhibit the formation of free radicals. Furthermore, alginate showed antibacterial activity and high biocompatibility. Incorporation of silver into alginate fibers increased antimicrobial activity and improved the binding affinity for elastase, matrix metalloproteases-2, and the proinflammatory cytokines tested. Addition of silver also enhanced the antioxidant capacity. However, a distinct negative effect of silver-containing alginates on human HaCaT keratinocytes was noted in vitro.     

The efficacy of hydroxyapatite composite impregnated with amphotericin B

We investigated the efficacy of local biodegradable composites composed of hydroxyapatite-plaster of paris and either chitosan or alginate binder impregnated with amphotericin B. Antifungal activity was tested for Candida albicans using a modified disc diffusion technique for 6 weeks and compared with similarly impregnated polymethylmethacrylate. The physicochemical properties of each preparation were evaluated using scanning electron microscopy and Fourier transform infrared spectroscopy. The antifungal activity of amphotericin B eluted from the hydroxyapatite composites was significantly greater than the polymethylmethacrylate after 7 days. The hydroxyapatite composites and the polymethylmethacrylate system sustained their antifungal activity for at least 1 month. However, after 5 weeks, the antifungal activities of the polymethylmethacrylate systems rapidly lessened, while the hydroxyapatite composites sustained their activities at a much higher level. We found no difference in antifungal activity between the hydroxyapatite composite using either the chitosan or alginate binder. Scanning electron microscopy and Fourier transform infrared spectroscopy revealed the drug release profile. The hydroxyapatite composites impregnated with amphotericin B showed superior antifungal efficacy over those loaded in polymethylmethacrylate in an in vitro study, but additional in vivo research is needed to confirm this result.