Antimicrobial activity of extracts of local cough mixtures on upper respiratory tract bacterial pathogens

The punched-hole and the paper disc diffusion methods were used in screening for the antimicrobial activity of six common ingredients used locally in cough mixtures, against the following bacteria: Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus. Enterococcus faecalis, Escherichia coli, Salmonella spp, Salmonella paratyphi, Shigella dysenteria, Shigella sonnei and Candida albicans. The results, evaluated as the diameter of zone of inhibition of microbial growth, showed that lime, garlic onion, onion and honey were active against Staphylococcus aureus, Streptococcus faecalis, Candida albicans, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Salmonella spp and Shigella dysenteriae. Bitter-kola nut extract and palm kernel oil showed no antimicrobial activities against any of the tested organisms. None of the extracts inhibited the growth of Salmonella paratyphi and Shigella sonnei and the most susceptible organisms were Escherichia coli and Salmonella spp.     

维吾尔族和汉族不同龋敏感儿童变异链球菌和远缘链球菌的检测

目的研究维吾尔族和汉族不同龋敏感儿童牙菌斑中变异链球菌和远缘链球菌的检出量,分析变异链球菌及远缘链球菌与不同民族儿童乳牙龋齿发生的关系,为不同民族儿童乳牙龋的防治提供依据。方法采用T-A克隆技术制备变异链球菌ATCC25175、远缘链球菌ATCC6715、内参基因16S rRNA的质粒标准品,应用SYBR Green I荧光定量聚合酶链反应对变异链球菌和远缘链球菌进行定量检测。结果维吾尔族儿童高龋组远缘链球菌的检出量高于汉族儿童高龋组[(1.06×105±0.43×103)copies.μL-1vs(8.29×104±1.20×104)copies.μL-1],差异有统计学意义(P<0.05),而维吾尔族、汉族儿童高龋组变异链球菌检出量比较差异无统计学意义(P>0.05),同时维吾尔族和汉族儿童远缘链球菌和变异链球菌的检出量高龋组均高于无龋组,差异均有统计学意义(P<0.05)。结论远缘链球菌可能是维吾尔族儿童乳牙龋高发的危险因素。     

纳米载银无机抗菌剂对义齿基托树脂抗菌性能的影响

目的研究纳米载银无机抗菌剂对义齿基托树脂抗菌性能的影响。方法纳米载银无机抗菌剂FUMAT T200-4,按0%(对照组)、1%、2%、3%、4%、5%、7%、10%(V/V)比例添加在加热固化型义齿基托树脂中。采用薄膜密着法检测抗菌剂对变形链球菌、白色念珠菌的抑菌作用,并分析比较抗菌剂添加比例与基托树脂抗菌性能的相关性。结果添加纳米载银无机抗菌剂的基托树脂对变形链球菌、白色念珠菌具有良好的抑菌作用。抗菌剂添加比例1%~10%组对变形链球菌的抑菌率分别为24.5%、73.3%、80.2%、87.2%、90.7%、96.5%、100%,对白色念珠菌的抑菌率分别为26.3%、46.7%、53.3%、63.1%、69.9%、73.2%、79.8%,抗菌性能随添加比例的上升而明显提高。结论纳米载银无机抗菌剂的添加赋予了基托树脂良好的抗菌性能。     

新型抗菌肽KR-1的设计、筛选及抗菌活性评价

目的 构建高活性、低毒性的新型抗菌肽,对其抗变异链球菌及其他口腔致病菌的活性进行评价,探讨其在防治龋病中的潜在应用价值。方法 以天然抗菌肽Histatins5的类似物Dhvar4为模版合成新型抗菌肽KR-1、KR-2。通过所设计抗菌肽对变异链球菌的最小抑菌浓度（MIC）实验,兔血红细胞溶血试验以及CCK-8法,筛选出高活性、低毒性的目标抗菌肽;使用96孔板培养变异链球菌生物膜,分为实验组（用浓度梯度为0.6×、0.8×、1×、2×MICs的KR-1进行处理）与阳性对照组（用浓度梯度为0.6×、0.8×、1×、2×MICs的洗必泰进行处理）,通过结晶紫染色定量法观察生物膜量的改变;使用10×MIC浓度KR-1作用于变异链球菌生物膜后通过激光共聚焦显微镜观察结构的改变;通过KR-1作用口腔链球菌后杀菌所需的时间探讨目标抗菌肽对口腔链球菌的抗菌效率。结果 实验测得KR-1及KR-2的MIC分别为3.2 μmol/L和12.8 μmol/L,有效浓度下,兔血红细胞溶血率分别为0.35%和48.8%,24 h牙龈成纤维细胞存活率分别为72.96 %和21.94 %,将活性较高、生物相容性较好的KR-1作为目标抗菌肽;经结晶紫染色后测定KR-1的50%生物膜最小抑制浓度（MBIC50）低于1.92 μmol/L,且浓度为2.56 μmol/L时效果优于阳性对照组洗必泰（P=0.001）,共聚焦显微镜下观察可见经KR-1处理后生物膜结构疏松;KR-1在5 min内可杀灭约90%细菌。结论 KR-1抗菌肽具有较强的抗菌活性和较低的毒性,且有良好的抗变异链球菌生物膜作用。     

肉豆蔻挥发油体外抗病原微生物活性研究

目的 探讨肉豆蔻挥发油体外抗病原微生物活性。方法 采用琼脂平板2倍稀释法测定肉豆蔻挥发油对大肠埃希菌和金黄色葡萄球菌等16种67株临床分离菌和白假丝酵母菌14株、非白假丝酵母菌1株临床分离真菌的最低抑菌浓度（MIC）;单因素方差分析法比较肉豆蔻挥发油对金黄色葡萄球菌、白假丝酵母菌、大肠埃希菌、洛菲不动杆菌与肺炎克雷伯菌等不同种属真菌和细菌的抑菌活性。结果 肉豆蔻挥发油除对铜绿假单胞菌抑菌活性相对较低（MIC为4.25~8.50 mg/mL）外,对其余受试细菌有较强的抑菌活性（MIC为0.07~1.06 mg/mL）;肉豆蔻挥发油对白假丝酵母菌和非白假丝酵母菌均有较强的抗真菌活性,MIC分别为0.07~0.53mg/mL和0.07mg/mL。统计分析表明,肉豆蔻挥发油对白假丝酵母菌的MIC明显低于对大肠埃希菌和金黄色葡萄球菌的MIC（P〈0.01）,对肺炎克雷伯菌的抑菌活性明显强于对金黄色葡萄球菌、大肠埃希菌的抑菌活性（P〈0.01,P〈0.05）,对其它种属细菌之间的抑菌活性差异无统计学意义（P〉0.05）。结论 肉豆蔻挥发油具有较强的抗细菌和抗真菌活性,可用于新型抗菌药物的开发,运用前景广阔。     

The in-vitro antimicrobial activity of Abrus precatorius (L) fabaceae extract on some clinical pathogens

OBJECTIVES: To investigate the in-vitro antimicrobial activities of the extracts of Abrus precatorius on some clinical isolates as resistance to available and affordable antibiotics by these pathogens is on the increase. METHOD: In this study the antimicrobial effects of the extracts of Abrus precatorius from leaves, stem and the seed oil were tested against Staphylococcus aureus ATCC 25923, three clinical S. aureus isolates from different sources, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus anginosus (S.milleri), Bacillus subtilis, Corynebacterium spp (toxigenic strain of the mitis biotype), Escherichia coli ATCC 25922, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa as well as Candida albicans using the agar well diffusion technique. Aqueous and methanolic extraction, using the soxhlet extractor was carried out on all plant parts used while petroleum ether was the solvent used to extract the seed oil. To measure the MIC values, various concentrations of the stock, 512, 256, 128, 64, 32, 16, 8 and 4 microg/ml were assayed against the test bacteria. RESULT: At the different concentrations of the extracts used (512 microg/ml - 4 microg/ml), Staphylococcus aureus was the most sensitive organism with an MIC of 8 ug/ml for the leaf extract. Extract from the stem and seed oil were potent against some of the gram-positive bacteria and Candida albicans but not against S anginosus, E. faecalis and gram-negative bacteria tested. The pH of the extracts ranged between pH5 and pH8. This study demonstrates that Abrus precatorius particularly the seed oil has a potent antimicrobial activity. CONCLUSION: The results substantiate the ethno botanical use of different parts of Abrus precatorius for the treatment of various bacteria-related diseases. Topical application of Abrus precatorius extracts in ointments may be recommended especially for treating superficial infections caused by Staphylococcus aureus.     

白色念珠菌麦角甾醇通路影响变异链球菌致龋力的研究

  目的  探究白色念珠菌（C. albicans）对变异链球菌（S. mutans）生长及毒力的影响,验证麦角甾醇通路在其中的作用。  方法  将S. mutans菌株UA159、C. albicans野生型5314单独培养及共培养（体积比1∶1混合）24 h后,检测各组菌液光密度（OD）600 nm值,并利用菌落形成单位（colony-forming units,CFU）计数检测S. mutans浓度,以反映C. albicans对S. mutans生长的影响;利用蒽酮法检测生物膜胞外多糖产量,pH计检测菌液产酸能力,以反映C. albicans对S. mutans毒力的影响;将不同C. albicans麦角甾醇合成相关通路突变株与S. mutans共培养后,检测突变株对S. mutans生长的影响;利用0 mg/L、0.012 5 mg/L、0.025 mg/L氟康唑抑制C. albicans麦角甾醇合成相关通路,24 h后检测C. albicans野生型和S. mutans在单独培养和混合培养下CFU的变化,以验证该通路作用。  结果  C. albicans野生型与S. mutans共培养后,与S. mutans 单独培养组相比,混合菌液中OD₆₀₀值和CFU升高（P<0.05）,S. mutans胞外多糖产量增加（P<0.05）,pH下降更明显（P<0.05）。42株C. albicans突变株与S. mutans共培养后,有14株菌对S. mutans促进生长的作用消失（P<0.05）,其中包含6株C. albicans麦角甾醇合成相关通路的突变株,这6株与S. mutans共培养后,菌液中S. mutans的CFU不变或下降。添加0.012 5 mg/L、0.025 mg/L氟康唑抑制麦角甾醇通路后,C. albicans 野生型与 S. mutans混合培养的菌液中,S. mutans的CFU较未添加氟康唑组降低（P<0.05）,而C. albicans单独培养组、S. mutans单独培养组的CFU无明显变化（P>0.05）,C. albicans野生型与S. mutans混合培养的菌液中C. albicans的CFU也无明显改变（P>0.05）。  结论  C. albicans能通过麦角甾醇相关通路增强S. mutans生长能力及毒力,此过程可被氟康唑抑制,有望成为防治龋病的新策略。     

新型阳离子卟啉的设计合成与抗微生物活性

目的探讨新型阳离子卟啉化合物及其金属络合物的合成及光动力抗菌活性。方法由缩合反应得到的四吡啶卟啉与一系列苄卤反应得到10个新型的阳离子卟啉化合物;采用琼脂双倍稀释法考查上述化合物对金黄色葡萄球菌、大肠杆菌、绿脓杆菌和白色念珠菌的光动力抑菌活性。结果合成得到10个新的阳离子卟啉化合物对革兰阳性金黄色葡萄球菌均表现出显著的光抑制作用,尤其是化合物3a、4a的MIC80分别为2μg/ml和0.5μg/ml;对真菌白色念珠菌也有一定的抑菌活性;而对革兰阴性大肠杆菌的抑制作用较低,绿脓杆菌则表现出对所有化合物的耐药性。阳离子卟啉的光抑菌活性随苯环上取代基吸电子能力的增强而降低。结论新型阳离子卟啉化合物对金黄色葡萄球菌有良好的光抑制活性。     

月桂挥发油体外抗病原微生物活性研究

目的 探讨月桂挥发油对临床分离细菌和真菌的体外抗菌活性,为月桂在治疗感染性疾病中的开发与运用奠定基础.方法 采用琼脂平板二倍稀释法测定了月桂挥发油对金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌共16种65株临床分离细菌、14株白假丝酵母和1株非白假丝酵母临床分离真菌的最低抑菌浓度.用SPSS 17.0软件中单因素方差分析法比较分析了月桂挥发油分别对金黄色葡萄球菌、大肠埃希菌、肺炎克雷伯菌、洛菲不动杆菌和白假丝酵母菌共5个不同种属细菌和真菌抑菌活性的强弱.结果 月桂挥发油除对铜绿假单胞菌无明显抗菌活性外,对其余受试细菌均有较强的抗菌活性,MIC为0.27 mg/mL～2.15 mg/mL;月桂挥发油对白假丝酵母菌和非白假丝酵母菌均有较强的抗菌活性,MIC分别为0.07～0.54 mg/mL和0.03 mg/mL;月桂挥发油对白假丝酵母菌和洛菲不动杆菌的抑菌活性明显强于对金黄色葡萄球菌、大肠埃希菌的抑菌活性（P＜0.01）,对金黄色葡萄球菌、大肠埃希菌和肺炎克雷伯菌的抑菌活性比较,差异无统计学意义（P＞0.05）.结论 月桂挥发油有较强的抗细菌和抗真菌活性,具有用于防治感染性疾病-新型抗菌药物的开发和运用前景.     

抗变异链球菌多肽的设计、筛选及抗菌效果评价

目的构建抗变异链球菌的低毒、高活性、快速的新型抗菌肽，并探讨其在防治龋病方面的潜能。方法根据两亲性正电性 α-螺旋结构抗菌肽的设计理念，对乳酸杆菌拮抗变异链球菌的代谢产物reuterin 6和/或gassericinA进行活性改造，分别通过细 菌敏感性实验、细胞毒性实验和杀菌-时效实验来评估衍生肽的抗菌效果和生物相容性，再进一步检测目标抗菌肽抗变异链球 菌的速率、抗多种口腔致病菌的活性和发展耐药菌株的能力。结果构建了6条AT-1衍生肽，并从中筛选出了低毒、高活性、快 速的新型抗菌肽AT-7；具有高疏水性、不完美两亲性的AT-7抑制变异链球菌、牙龈卟啉单胞菌和黏性放线菌等口腔致病菌的最 小抑菌浓度是3.3 μmol/L，在5 min内即可抑制88.7%的变异链球菌，以及连续诱导10代的处理仍不能产生耐AT-7的变异链球 菌。结论疏水性和不完美两亲性都是决定抗菌肽的抗菌效果的重要因素；抗菌肽AT-7具有转化为口腔临床用药的潜力。     

绿原酸防龋的实验研究

目的 研究绿原酸对龋病发生发展的抑制效果。方法 制备不同浓度绿原酸,采用液体稀释法检测其体外抑制变形链球菌和远缘链球菌的效果;建立SD大鼠人工龋模型,分别用绿原酸溶液、甲硝唑洗必泰溶液和蒸馏水给大鼠施药,采用Keyes记分法观察绿原酸对大鼠口腔内龋齿发生发展的抑制效果。结果 绿原酸溶液对变形链球菌ATCC10449株和远缘链球菌OMZ65株的最小抑菌浓度均为2.5 mg/mL,最小杀菌浓度分别为7.5 mg/mL和5 mg/mL。在人工龋大鼠模型中,与蒸馏水相比,绿原酸组龋齿计分明显降低,而与甲硝唑洗必泰组相近。结论 绿原酸对变形链球菌和远缘链球菌生长有明显抑制作用,并可有效抑制大鼠龋齿的发生。     

赤丹丸与其组方药材的体外抑菌试验

目的：研究赤丹丸及其组方药材的体外抑菌作用。方法：采用液体培养基2倍稀释法测定赤丹丸及其组方药材的水提取物和乙醇提取物对金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌、白色念珠菌的体外最低抑菌浓度（MIC）和最低杀菌浓度（MBC）。结果：赤丹丸及其组方药材的水提取物和醇提取物对白色念珠菌的抑菌作用明显弱于对其它3种菌的作用（P〈0．05），其中药材的水提取物体外抑制白色念珠菌作用相对较强（P〈0．05）；各种提取物对金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌的抑菌作用也各有差异。药材水提取物对铜绿假单胞菌、白色念珠菌的抑菌作用最强（P〈0．05）；赤丹丸醇提取物对金黄色葡萄球菌、大肠埃希菌的抑菌作用最强（P〈0．05）。结论：赤丹丸及其组方药材的水提取物与醇提取物对金黄色葡萄球菌、大肠埃希菌、铜绿假单胞菌、白色念珠菌均具有体外抑菌作用。     

葡萄糖基转移酶多克隆抗体对远缘链球菌定居的影响

目的:观察局部应用葡萄糖基转移酶多克隆抗体对远缘链球菌定居的影响。方法:本实验选用30只出生后25 d小鼠,平均分为对照组与实验组,分别在出生后32、36、40、44、48和52 d,在鼠的磨牙涂50 μL磷酸盐缓冲液(对照组)及50 μL葡萄糖基转移酶多克隆抗体(实验组)。在实施第3次涂布后,所有鼠用远缘链球菌OMZ176(血清型d)进行接种,随后立即给予致龋饮食。在用远缘链球菌接种40 d后,处死小鼠,拔除磨牙,取细菌标本,用轻唾(MS)平板培养基定量培养,分别计数远缘链球菌数和细菌总数。 结果:远缘链球菌数占细菌总数的百分比,实验组(37.01±12.08)%,对照组(48.20±14.78)%。经统计学分析表明实验组远缘链球菌定居水平明显低于对照组(P<0.01)。 结论:葡萄糖基转移酶多克隆抗体局部应用能显著降低远缘链球菌的定居。     

宫颈泰栓药效学研究

目的观察宫颈泰栓的收敛、抗炎、抗菌作用．方法取新鲜蛋清液，豚鼠直肠和皮肤，观察宫颈泰栓的收敛作用；取体重２５～３０ｇ健康小鼠１２０只，随机分为６组，观察宫颈泰栓对二甲苯造成鼠耳炎症反应的影响；取１４０～１６５ｇ健康大鼠如只，随机分为９组．观察宫颈泰枪对滤纸片到成肉芽肿模型的影响；用平皿法和试管法观察宫颈泰栓对金葡菌、大肠杆菌、绿脓杆茵、链球菌、白色念珠菌等细菌的抗菌作用．结果宫颈泰栓（或粉）可使蛋清液沉淀．使豚鼠肠粘膜和皮肤变白、紧缩等；对二甲苯造成鼠耳炎症反应有明显抑制作用；对小鼠尾部绿脓杆菌感染有明显保护作用；对金葡菌、链球菌、大肠杆菌、绿脓杆茵、白色念球菌均有明显抑菌作用。结论宫颈泰栓有明显收敛、抗炎、抗菌作用，是治疗宫颈糜烂较理想的药物．     

滇东南26种中草药体外抗菌活性研究

目的测定26种采自滇东南红河州原始森林中草药的80%乙醇提取物体外抗菌活性及对MRSA活性,筛选出抑菌效果好的药材进一步提取分离并追踪其有效成分。方法制备26种云南中草药乙醇提物,采用常规琼脂扩散法对金黄色葡萄球菌,大肠埃希菌,白假丝酵母菌,铜绿假单胞菌以及临床分离得到的MRSA菌株进行体外抑菌试验,倍比稀释法测定MIC（最小抑菌浓度）、MBC（最低杀菌浓度）。结果 26种云南中草药的醇提物中有16种对标准金黄色葡萄球菌标准菌株（ATCC 25923）、大肠埃希菌标准菌株（ATCC 25922）、铜绿假单胞菌标准菌株（ATCC27853）、白假丝酵母菌标准菌株（ATCC Y0109）均有不同程度的抑制活性;其中野梧桐,乔木茵芋等8种中草药对标准金黄色葡萄球菌的抑制作用较好,对标准金黄色葡萄球菌的抑菌圈大小在11～24mm之间,对耐甲氧西林金黄色葡萄球菌（MRSA）菌株抑菌活性在9～26mm之间,MIC在8～512μg/mL之间。结论野梧桐,乔木茵芋等8种中药具有广谱的抗菌活性,且对MRSA菌株也有一定的抑制作用。     

玉米须抗菌活性的初步研究

目的：探讨玉米须的体外抗菌活性。方法：采用琼脂扩散法和试管连续稀释法测定玉米须对常见致病菌和条件致病菌的体外抗菌活性及最低抑菌浓度（MIC）。结果：（1）玉米须对金黄色葡萄球菌和乙型溶血性链球菌皆有明显的抗菌活性，抑菌圈直径分别为21mm和16mm。对金黄色葡萄球菌的最低抑菌浓度为0．5g／ml。（2）玉米须对大肠埃希菌、福氏志贺氏菌、伤寒沙门氏菌、铜绿假单胞菌无抗菌活性。结论：玉米须对金黄色葡萄球菌和乙型溶血性链球菌有较好的体外抑菌活性。     

ICU耐甲氧西林的金黄色葡萄球菌的分离及药敏分析

目的:探讨重症监护室(ICU)金黄色葡萄球菌(SA)的分离率及药敏情况,为有效预防控制感染提供科学依据。方法:常规方法分离金黄色葡萄球菌菌种,用法国生物梅里埃公司VITEK-2compat全自动微生物分析仪系统进行鉴定及药敏分析,并对耐甲氧西林的金黄色葡萄球菌(MRSA)及甲氧西林敏感的金黄色葡萄球菌(MSSA)药敏结果进行分析比较。结果:ICU 774株菌株中细菌分离率排在前7位的细菌分别是鲍曼不动杆菌占18.3%,白假丝酵母菌14.5%,铜绿假单胞菌占11.3%,金黄色葡萄球菌占11.1%,大肠埃希菌占6.2%,嗜麦芽窄食单胞菌占6.2%,肺炎克雷伯菌占6.1%,金黄色葡萄球菌排在第四位。86株金黄色葡萄球菌中MRSA47株占54.7%,MSSA39株占45.3%(89.5%分离于痰液)。药敏试验提示MRSA对抗菌药物呈多重耐药;除利福平、复方新诺明、万古霉素、呋喃妥因、奎诺普汀/达福普汀、利奈唑胺外,MRSA对其余9种抗菌药耐药率均高于MSSA,差异有统计学意义(P<0.05或P<0.01)。结论:ICU MRSA的分离率及耐药率均较高,MRSA表现为多重耐药性,应注意合理选用抗生素治疗并采取有效措施积极预防和控制好院内感染。     

Antimicrobial effect of acidified nitrate and nitrite on six common oral pathogens in vitro

Background Salivary nitrate is positively correlated with plasma nitrate and its level is 9 times the plasma level after nitrate loading. Nitrate in saliva is known to be reduced to nitrite by oral bacteria. Nitrate and nitrite levels in saliva are 3-5 times those in serum in physiological conditions respectively in our previous study. The biological functions of high salivary nitrate and nitrite are still not well understood. The aim of this in vitro study was to investigate the antimicrobial effects of nitrate and nitrite on main oral pathogens under acidic conditions. Methods Six common oral pathogens including Streptococcus mutans NCTC 10449, Lactobacillus acidophilus ATCC 4646, Porphyromonas gingivalis ATCC 33277, Capnocytophaga gingivalis ATCC 33624, Fusobacterium nucleatum ATCC 10953, and Candida albicans ATCC 10231 were cultured in liquid medium. Sodium nitrate or sodium nitrite was added to the medium to final concentrations of 0, 0.5, 1, 2, and 10 mmol/L. All of the microorganisms were incubated for 24 to 48 hours. The optical densities （OD） of cell suspensions were determined and the cultures were transferred to solid nutrient broth medium to observe the minimum inhibitory concentration and minimum bactericidal/fungicidal concentration for the six tested pathogens. Results Nitrite at concentrations of 0.5 to 10 mmol/L had an inhibitory effect on all tested organisms at low pH values. The antimicrobial effect of nitrite increased with the acidity of the medium. Streptococcus mutans NCTC 10449 was highly sensitive to nitrite at low pH values. Lactobacillus acidophilus ATCC 4646 and Candida albicans ATCC 10231 were relatively resistant to acidified nitrite. Nitrate at the given concentrations and under acidic conditions had no inhibitory effect on the growth of any of the tested pathogens. Conclusion Nitrite, at a concentration equal to that in human saliva, is both cytocidal and cytostatic to six principal oral pathogens in vitro, whereas nitrate at a similar concentration has no antimicrobial effect on these organisms.     

甜菜碱体外抑菌活性的研究

目的 研究甜菜碱对临床病原菌的体外抑菌活性.方法 采用试管二倍稀释法进行体外抑菌试验,测定甜菜碱对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌和白色念珠菌的最小抑菌浓度.结果 甜菜碱对4种病原菌标准菌株的最小抑菌浓度（MIC）为大肠杆菌的MIC 6.25 mg/ml、铜绿假单胞菌的MIC 3.125 mg/ml、金黄色葡萄球菌的MIC 6.25 mg/ml、白色念珠菌的MIC 25 mg/ml.结论 甜菜碱对4种病原菌的标准菌株都有明显的抑菌作用,尤其对铜绿假单胞菌的MIC值最低.     

Effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria in vitro

Background Cecropin-XJ belongs to cecropin-B, which is the most potent antibacterial peptide found naturally. The aim of this study was to investigate the effects of cecropin-XJ on growth and adherence of oral cariogenic bacteria.Methods Four oral cariogenic bacteria (Streptococcus mutans, Lactobacillus acidophilus, Actinomyces viscosus and Actinomyces naeslundii) were chosen for this experiment. The minimal inhibitory concentrations (MICs) and reductive percent of bacterial growth were used to assay the antibacterial activity of cecropin-XJ. Mammalian cytotoxicity of cecropin-XJ was tested with human periodontal membrane fibroblasts by tetrazolium (MTT) colorimetric assay. The bacterial morphological changes induced by cecropin-XJ were examined on scanning electron microscope (SEM). The influence of cecropin-XJ on bacterial adhesion to saliva-coated hydroxyapatite （S-HA） was measured by scintillation counting.Results The MICs of cecropin-XJ for inhibition of the growth of four bacteria ranged from 4.0 to 42.8 μmol/L with the highest susceptible to A. naeslundii and the lowest susceptible to L. acidophilus. At pH 6.8, 5.5 and 8.2, 1/2 MIC of cecropin-XJ reduced the number of viable bacteria by 40.9%, 67.8% and 32.8% for S. mutans and by 28.1%, 57.2% and 37.9% for L. acidophilus. The activities against S.mutans and L. acidophilus increased at pH 5.5 compared with pH 6.8 (P&lt;0.01, respectively). In present of 50% saliva, 1/2 MIC of the peptide decreased the direct count of viable cells by 29.2% and 14.4% for S. mutans and L. acidophilus, respectively (P&lt;0.01 and P&gt;0.05, respectively), whereas almost no reduction counts were detected in the presence of 20% serum for both bacteria (P&gt;0.05, respectively). Mammalian cytotoxicity of cecropin-XJ from 1.0 to 100 μmol/L exhibited no cytotoxicity against human periodontal membrane fibroblasts (P&gt;0.05). Bacterial morphological changes induced by MIC of cecropin-XJ examined on SEM showed cell surface disruption. Furthermore, the ability of A. naeslundii adhesion to S-HA decreased significantly with MIC of cecropin-XJ for 10 and 20 minutes (P=0.001 and 0.000, respectively), and S. mutans, A. viscosus to S-HA decreased significantly with MIC of cecropin-XJ for 20 minutes( P=0.000, respectively). Conclusions Cecropin-XJ exhibited bactericidal action against cariogenic pathogens, and the antibacterial activity enhanced in the acid environment. The results also demonstrate that cecropin-XJ prevents S. mutans and actinomyces adsorption to S-HA. These findings suggest that Cecropin-XJ may have potential to prevent caries.