双歧杆菌试管内生物拮抗作用研究

目的 本实验从正常青少年体内分离出1株双歧杆菌,通过试管内研究双歧杆菌对大肠埃希菌和粪肠球菌的生物拮抗作用.为双歧杆菌临床应用及食品开发提供一定的基础理论依据和广阔的市场前景.方法 本项研究以从佳木斯大学健康学生体内分离出1株双歧杆菌为试材,将大肠埃希菌、粪肠球菌接种于PYG液体培养基中,37℃厌氧培养48 h,将菌液浓度利用分光光度计法调到2麦氏.将大肠埃希菌对照组分为10支,分离的双歧杆菌+大肠埃希菌组10支,分离的双歧杆菌对照组10支,分离的双歧杆菌+粪肠球菌组10支,粪肠球菌对照组10支,将以上50个试管全部置于厌氧培养箱内37℃培养48 h,将培养好的大肠埃希菌和粪肠球菌进行梯度稀释,然后用微量移液器吸取标本于每个培养基上滴3滴,每滴滴上由高稀释度向低稀释度,液体量为10 μL的菌液.晾干滴种好的培养基于适宜条件进行培养并选出适合菌落生长的稀释度,计算同一稀释度平均菌落数(x).结果 双歧杆菌12 h时对大肠埃希菌生长无显著性,在24h时检测不到大肠埃希菌的存在.12和24h时粪肠球菌与双歧杆菌混合组与粪肠球菌对照组相比,差异均无统计学意义(P＞0.05).结论 体外对照实验研究该双歧杆菌对大肠埃希菌和粪肠球菌的生物拮抗作用,此株双歧杆菌只对大肠埃希菌有抑制作用,而对粪肠球菌无抑制作用,机制需要深入研究.     

矿物微尘对人体肠道菌群单一代表性菌株的体外作用研究

研究了矿物微尘对人体肠道菌群主要代表性菌株大肠埃希菌和嗜酸乳杆菌的体外作用。矿物微尘对大肠埃希菌生长起抑制作用,微尘浓度达3%时即对大肠埃希菌生长显著抑制,微尘浓度达20%时大肠埃希菌生长即受完全抑制,微尘浓度从3%到20%,大肠埃希菌虽受抑制但能生长,表明大肠埃希菌矿物微尘耐受能力较强。矿物微尘对嗜酸乳杆菌生长影响复杂,低浓度时起促进作用,较高浓度时起抑制作用,微尘浓度达5%时嗜酸乳杆菌生长即受完全抑制,嗜酸乳杆菌矿物微尘耐受能力较弱,远小于大肠埃希菌。确立矿物微尘对人体肠道代表性细菌的抑制浓度及致死浓度为环保监测和城市空气质量监控提供了科学依据。     

腹部外科患者术后肠道菌群分布及血清ADPN、TLR4、sTREM-1水平的变化CSCD

目的 观察腹部外科患者术后肠道菌群分布及血清脂联素（ADPN）、Toll-样受体4(TLR4)、可溶性髓样细胞触发受体（sTREM-1）水平变化,为该类患者的治疗提供参考。方法 选择2022年5月至2023年6月本院收治的87例腹部外科患者为研究组,选择同期84名健康体检者作为对照组。比较两组对象肠道菌群数量及研究组手术前后血清ADPN、TLR4、sTREM-1水平,并分析肠道菌群数量和这3项血清指标是否存在相关性。结果 研究组患者术前肠道大肠埃希菌、肠球菌数量及血清TLR4、sTREM-1水平均较对照组高,双歧杆菌、乳杆菌数量及血清ADPN水平均较对照组低（均P<0.05）;术后1个月,研究组患者肠道大肠埃希菌、肠球菌数量及血清TLR4、sTREM-1水平均高于术前,双歧杆菌、乳杆菌数量及血清ADPN水平均低于术前（均P<0.05）。Pearson相关性分析显示,腹部外科患者术后1个月血清ADPN水平与大肠埃希菌、肠球菌数量均呈负相关（r=-0.564、-0.618,均P<0.001）,与双歧杆菌、乳杆菌数量均呈正相关（r=0.561、0.547,均P<0.001）;血清TLR4、sTREM-1水平与大肠埃希菌、肠球菌数量均呈正相关（TLR4:r=0.417、0.571,P=0.008、<0.001;sTREM-1:r=0.589、0.634,均P<0.001）,与双歧杆菌、乳杆菌数量均呈负相关（ADPN:r=-0.561、0.547,均P<0.001;TLR4:r=-0.394、-0.441,P=0.011、0.006;s TREM-1:r=-0.578、-0.657,均P<0.001）。结论 腹部外科患者术后存在显著的肠道菌群变化,表现为大肠埃希菌和肠球菌数量增多,双歧杆菌和乳杆菌数量减少,同时伴有血清ADPN、TLR4、s TREM-1水平异常。且肠道菌群变化与血清ADPN、TLR4、sTREM-1水平均存在相关性。     

加替沙星对小鼠肠道菌群的影响

目的 了解加替沙星正常剂量用药和非正常剂量用药方式对小鼠肠道菌群的影响.方法 24只昆明小鼠随机分为3组,每组8只,对照组只灌胃生理盐水,另外2组分别按正常剂量和正常剂量的一半给小鼠灌胃加替沙星溶液,7 d后无菌采取小鼠粪便,观察各组小鼠粪便中双歧杆菌、类杆菌、乳酸杆菌、大肠埃希菌及肠球菌数量.结果 加替沙星灌胃7 d后,与给药前相比,肠杆菌和肠球菌药敏结果无明显变化.灌胃前后肠杆菌对CIP、LEV、GAT、AM、CRO、AMK、NOR均敏感,肠球菌对AM、LEV、VA、GAT均敏感,对NOR、CIP、CRO敏感性不同.2种用药方式可导致大肠埃希菌数量显著减少(P＜0.05),肠球菌数量稍有增加(P＞0.05).而双歧杆菌、乳酸杆菌和类杆菌数量无明显变化(P＞0.05).结论 加替沙星2种用药方式短时期对肠道菌群影响不大(肠杆菌除外),不易产生耐药性.其杀灭肠杆菌的作用远大于对厌氧菌的作用.     

低出生体重儿肠道微生态构建影响因素的动态监测

目的 动态监测低出生体重儿肠道菌群,分析不同体重、不同喂养方式及疾病状态等因素对患儿肠道微生态的影响,为规范临床低出生体重儿宫外营养支持措施及治疗手段提供依据。方法 应用16S rRNA荧光定量PCR技术检测正常新生儿和低出生体重儿生后第1、3、7天粪便中大肠埃希菌、肠球菌、乳杆菌及双歧杆菌的含量。结果 （1）在生后7 d内,无论正常新生儿还是低出生体重儿,其粪便中大肠埃希菌、肠球菌、乳杆菌和双歧杆菌的含量均随日龄的增加而增加,且生后7 d内正常新生儿的粪便中大肠埃希菌、肠球菌、乳杆菌和双歧杆菌的含量均显著高于低出生体重儿（P<0.05）,正常新生儿生后7 d内粪便中各细菌的增长率均高于低出生体重儿。（2）体重2 000~2 500 g的低出生体重儿粪便中大肠埃希菌和肠球菌在各日龄中的含量明显高于体重<2 000 g的新生儿（P<0.05）;同时其粪便中双歧杆菌和乳杆菌含量在3日龄和7日龄阶段明显高于体重<2 000 g的新生儿（P<0.05）。（3）3日龄和7日龄母乳喂养组的低出生体重儿粪便中双歧杆菌和乳杆菌含量明显高于乳制品喂养组（P<0.05）;且母乳喂养组新生儿生后7日内粪便中大肠埃希菌、乳杆菌和双歧杆菌含量的增长率均高于乳制品喂养组,尤其是双歧杆菌的增长率（126.49% vs 54.81%）。（4）合并并发症的3日龄和7日龄的低出生体重儿,粪便中乳杆菌和双歧杆菌含量均明显低于无合并症的低出生体重儿（P<0.05）;且无并发症组的低出生体重儿其粪便中肠球菌、乳杆菌和双歧杆菌的增长率均高于有并发症组的低出生体重儿,大肠埃希菌增长率则低于有并发症组。结论 低出生体重儿肠道菌群的定植时间晚且数量少,体重、喂养方式及有无并发症是影响新生儿肠道菌群丰度的重要因素。母乳喂养可促进低出生体重儿肠道中益生菌的定植。疾病因素会导致肠道菌群丰度的降低,使肠道菌群紊乱,其程度可能与病情的严重程度相关。     

重症肺炎新生儿肠道菌群特征和应激反应及益生菌干预的效果CSCD

目的研究重症肺炎新生儿肠道菌群特征、应激反应及益生菌干预的效果,为此类患儿的治疗提供参考。方法选取2019年1月至2020年3月我院收治的105例重症肺炎新生儿作为试验组,并选取我院产科48例健康新生儿作为对照组。采用随机数字表法将试验组分为益生菌组(n=53)和常规组(n=52),常规组给予新生儿重症肺炎常规治疗,益生菌组在常规组基础上联合运用益生菌治疗。对比试验组和对照组患儿肠道菌群特征,同时对比益生菌组和常规组患儿治疗前后肠道菌群特征和应激反应指标水平。结果相比于对照组,试验组患儿肠道乳杆菌(t=15.454,P<0.001)、肠球菌(t=23.191,P<0.001)、大肠埃希菌(t=25.274,P<0.001)数量显著升高,双歧杆菌数量显著降低(t=46.012,P<0.001)。治疗后,两组患儿肠道乳杆菌、肠球菌、大肠埃希菌数量均降低,双歧杆菌数量升高,且相比于常规组,益生菌组患儿肠道乳杆菌(t=3.617,P<0.001)、肠球菌(t=7.826,P<0.001)、大肠埃希菌数量显著降低(t=5.799,P<0.001),双歧杆菌数量显著升高(t=12.750,P<0.001)。治疗后,两组患儿总抗氧化能力(T-AOC)、超氧化物歧化酶(SOD)水平均升高,丙二醛(MDA)水平降低;且相比于常规组,益生菌组T-AOC(t=18.302,P<0.001)、SOD(t=8.639,P<0.001)水平显著升高,MDA水平显著降低(t=22.816,P<0.001)。结论重症肺炎新生儿肠道菌群主要以乳杆菌、肠杆菌、大肠埃希菌数量升高,双歧杆菌数量降低为特征。益生菌治疗能有效恢复患儿肠道菌群稳定,改善患儿应激反应。     

两种生物状态肠道益生菌的粘附和粘附拮抗效应的对比研究

目的:研究活菌和灭活菌两种生物状态的肠道主要益生菌--德氏乳杆菌、双歧杆菌和肠球菌对肠黏膜上皮细胞粘附性及其对肠道几种常见病原菌的粘附拮抗效应.方法:用光镜和电镜技术分析了两种生物状态的三种益生菌对肠黏膜上皮细胞的粘附指数,通过排除实验、竞争实验和替代实验研究了两种生物状态益生菌对侵袭性大肠埃希菌、产毒性大肠埃希菌和痢疾志贺菌的粘附拮抗效应,应用平板扩散法观察了三种益生菌的代谢乏液对上述肠道病原菌的抑制能力.结果:德氏乳杆菌和肠球菌的灭活状态较活菌状态对肠黏膜上皮细胞的粘附性显著增高,双歧杆菌经灭活后对细胞的粘附性与活菌相比差异无显著性,两种生物状态的三种益生菌对肠道致病菌均具有粘附拮抗作用.滤过后的德氏乳杆菌、双歧杆菌和肠球菌的代谢乏液对侵袭性大肠埃希菌、产毒性大肠埃希菌和痢疾志贺菌均具有较明显的抑制作用,经42℃、65℃和100℃加热不影响德氏乳杆菌和双歧杆菌代谢乏液的抑菌作用.结论:灭活状态的德氏乳杆菌、双歧杆菌和肠球菌是具有潜在开发价值的微生态制剂.     

结肠癌患者肠道菌群变化的临床研究

目的 对比分析结肠癌患者肠道菌群数量变化的特点,为结肠癌的治疗提供新途径。方法 选取2014年6月至2015年6月在本院就诊的结肠癌患者48例为试验组,同期在本院体检的48例健康者为对照组。取两组患者粪便标本进行传统菌落培养与计数检测,同时采用荧光定量聚合酶链反应（qPCR）法检测肠道细菌相对含量与相关基因表达拷贝数。结果 菌落计数结果显示试验组大肠埃希菌、屎肠球菌和酵母菌数量多于对照组,而双歧杆菌和乳酸杆菌数量少于对照组,组间比较差异均有统计学意义（P0.05）。结论 结肠癌患者大肠埃希菌、屎肠球菌和酵母菌数量明显增加,双歧杆菌和乳酸杆菌数量明显减少,肠道菌群数量变化在结肠癌的发生和发展中可能发挥一定作用。     

肠道需氧优势菌群分离方法的建立及初步应用

采用双平板（ Ｍａｃ Ｃｏｎｋｅｙ 平板和血液琼脂平板） 法进行肠道需氧优势菌群。通过对１０９ 例慢性腹泻门诊患者和３０ 例健康成人进行需氧条件下肠道优势菌群分离鉴定,前者７３ 例分离到非大肠埃希菌优势菌群,占６７．０ ％ ,共２２ 种７６ 株细菌、３ 株真菌,其中Ｇ－ 杆菌１７ 种５５ 株,Ｇ＋ 球、杆菌５ 种２１ 株,以两种以上非大肠埃希菌为混合优势菌群者６ 例,占８．２ ％ （６／７３） ;而后者无一例有非大肠埃希菌优势菌群生长。结果表明,慢性腹泻与肠道需氧优势菌群种类显著相关（Ｐ＜ ０．００１） 。     

小鼠肠道菌群的多样性不因大肠埃希菌O157:H7感染而降低

目的探讨大肠埃希菌O157∶H7感染对小鼠肠道菌群的影响。方法采用大肠埃希菌O157∶H7菌悬液,灌胃制备感染小鼠。随后测定小鼠的生长情况和死亡率;收集肠道菌群,DGGE检测小鼠个体间肠道菌群的变化,高通量测序检测组间感染小鼠肠道菌群的变化。结果大肠埃希菌O157∶H7感染小鼠与正常对照组小鼠相比,小鼠体重、死亡率差异无统计学意义。DGGE结果显示,在不同小鼠个体之间,它们的肠道细菌的种类和数量存在明显差异。高通量测序结果显示,大肠埃希菌O157∶H7感染小鼠肠道菌群的多样性高于对照组,但优势菌的丰度有显著变化。结论大肠埃希菌O157∶H7感染,尽管极大改变了小鼠肠道优势菌群的比例,但没有降低其多样性。另外,小鼠个体间肠道菌群多样性的差异在微生态研究中不容忽视。     

复方薏苡仁方对小鼠肠道菌群及微环境的调节作用研究

目的 观察复方薏苡仁方调节小鼠肠道菌群功能及胃肠运动的效果,并考察复方薏苡仁方对小鼠盲肠内容物pH及肠黏膜结构等肠道内环境的影响。方法 参照《保健食品检验与评价技术规范》（2003版）的规定进行调节肠道菌群实验和小肠墨汁推进试验,检测小鼠盲肠内容物pH,并对肠道黏膜结构进行病理形态学观察。结果 （1）与给样前相比,复方薏苡仁方中、高剂量组肠杆菌数和低、高剂量组肠球菌数均明显减少（P<0.05）,中、高剂量组乳杆菌数和双歧杆菌数均明显或显著增加（P<0.05或P<0.01）,且高剂量组乳杆菌数和中、高剂量组双歧杆菌数明显高于阳性对照组（P<0.05）;（2）复方薏苡仁方各剂量组小鼠盲肠内容物pH值均显著降低（P<0.01）,且均低于阳性对照组,其中低、高剂量组差异有统计学意义（P<0.05或P<0.01）;（3）与正常对照组相比,复方薏苡仁方低、中、高剂量组小鼠十二指肠、空肠、回肠绒毛长度/隐窝深度比值（A/V）均明显或显著增加（P<0.05或P<0.01）,且中、高剂量组十二指肠、空肠及回肠A/V比值明显或显著高于阳性对照组（P<0.05或P<0.01）;（4）与模型对照组相比,复方薏苡仁方各剂量组小鼠小肠推进率均显著增加（P<0.01）,且均高于阳性对照组（P<0.01）。结论 复方薏苡仁方对调节肠道菌群及改善肠道微环境具有一定的促进作用。     

千金子不同极性部位对酪氨酸酶活性的影响

测定千金子醇提物不同极性部位对酪氨酸酶活性的影响。以L-酪氨酸为底物,采用比色法测定千金子不同极性部位对酪氨酸酶的抑制率。得到了千金子醇提物的乙酸乙酯相、正丁醇相和水相的半数抑制率(IC50值)分别为0.150 mg/mL,0.813 mg/mL,7.570 mg/mL,并对乙酸乙酯相进一步分离得到七叶内酯,其IC50值0.103 mg/mL。结果表明千金子中起到酪氨酸酶抑制性的物质为七叶内酯,主要分布在乙酸乙酯相中。为千金子中酪氨酸酶抑制性物质的筛选提供科学依据。     

双歧杆菌三联活菌散对儿童轮状病毒性肠炎患者肠道菌群及肠黏膜通透性的影响

目的 观察双歧杆菌三联活菌散对儿童轮状病毒性肠炎（RVE）患者肠道菌群和肠黏膜通透性的影响。方法 选择2016年1月至2017年8月于丽水市中心医院儿科门诊治疗的RVE患儿94例,随机分为观察组和对照组各47例。两组患儿均予饮食调整、补液及纠正电解质紊乱和酸碱失衡等治疗。观察组患儿加用双歧杆菌三联活菌散1.0 g/次,3次/d,温水冲服。观察两组患儿治疗前后肠道菌群（双歧杆菌、乳杆菌和大肠埃希菌）数量和肠黏膜通透性指标[内毒素（ETX）和D-乳酸]的变化,并比较其临床疗效。结果 治疗72 h后,观察组患儿双歧杆菌和乳杆菌数量明显上升,大肠埃希菌数量明显下降（P0.05）。治疗后观察组患儿双歧杆菌、乳杆菌数量较对照组更高,大肠埃希菌数量较对照组更低（P<0.05）。两组患儿治疗后血清ETX和D-乳酸水平均明显下降（P<0.05）,且观察组下降幅度更大（P<0.05）;同时观察组患儿总有效率高于对照组（χ2=4.11,P<0.05）。结论 双歧杆菌三联活菌散治疗儿童RVE的疗效确切,其作用机制可能与其能增加双歧杆菌和乳杆菌等有益菌的数量,减少大肠埃希菌等致病菌的数量,改善患儿肠道微生态状况;并与其能降低肠黏膜通透性和减少肠液的分泌渗出相关。     

Gram-negative bacteria aggravate murine small intestinal Th1-type immunopathology following oral infection with Toxoplasma gondii

Oral infection of susceptible mice with Toxoplasma gondii results in Th1-type immunopathology in the ileum. We investigated gut flora changes during ileitis and determined contributions of gut bacteria to intestinal inflammation. Analysis of the intestinal microflora revealed that ileitis was accompanied by increasing bacterial load, decreasing species diversity, and bacterial translocation. Gram-negative bacteria identified as Escherichia coli and Bacteroides/Prevotella spp. accumulated in inflamed ileum at high concentrations. Prophylactic or therapeutic administration of ciprofloxacin and/or metronidazole ameliorated ileal immunopathology and reduced intestinal NO and IFN-gamma levels. Most strikingly, gnotobiotic mice in which cultivable gut bacteria were removed by quintuple antibiotic treatment did not develop ileitis after Toxoplasma gondii infection. A reduction in total numbers of lymphocytes was observed in the lamina propria of specific pathogen-free (SPF), but not gnotobiotic, mice upon development of ileitis. Relative numbers of CD4(+) T cells did not differ in naive vs infected gnotobiotic or SPF mice, but infected SPF mice showed a significant increase in the frequencies of activated CD4(+) T cells compared with gnotobiotic mice. Furthermore, recolonization with total gut flora, E. coli, or Bacteroides/Prevotella spp., but not Lactobacillus johnsonii, induced immunopathology in gnotobiotic mice. Animals recolonized with E. coli and/or total gut flora, but not L. johnsonii, showed elevated ileal NO and/or IFN-gamma levels. In conclusion, Gram-negative bacteria, i.e., E. coli, aggravate pathogen-induced intestinal Th1-type immunopathology. Thus, pathogen-induced acute ileitis may prove useful to study bacteria-host interactions in small intestinal inflammation and to test novel therapies based on modulation of gut flora.     

"妈咪爱"治疗婴幼儿秋季腹泻的临床研究

目的 了解妈咪爱对轮状病毒肠炎（RV肠炎）的疗效及治疗前后肠道菌群变化。方法 随机取60例RV肠炎病例分析并分成2组：一组常规治疗,另一组在常规治疗基础上加妈咪爱治疗。除根据全国小儿腹泻会议评定标准,观察临床症状外,2组均在用药前,用药3、6d再进行正常菌群检测。结果 （1）VR肠炎可致肠道菌群失调;（2）妈咪爱治疗组疗效较常规治疗组疗效差异有显著性（P〈0．01）,同时4种正常菌群中的优势菌恢复较快,用药第6天肠道菌群基本恢复正常。结论 妈咪爱治疗RV肠炎有显著疗效,不仅临床症状恢复时间缩短,肠道菌群也很快恢复到平衡状态。     

ITRAQ-based quantitative proteomic analysis of processed <Emphasis Type="Italic">Euphorbia lathyris</Emphasis> L. for reducing the intestinal toxicity

Background

Euphorbia lathyris L., a Traditional Chinese medicine (TCM), is commonly used for the treatment of hydropsy, ascites, constipation, amenorrhea, and scabies. Semen Euphorbiae Pulveratum, which is another type of Euphorbia lathyris that is commonly used in TCM practice and is obtained by removing the oil from the seed that is called paozhi, has been known to ease diarrhea. Whereas, the mechanisms of reducing intestinal toxicity have not been clearly investigated yet.

Methods

In this study, the isobaric tags for relative and absolute quantitation (iTRAQ) in combination with the liquid chromatography-tandem mass spectrometry (LC-MS/MS) proteomic method was applied to investigate the effects of Euphorbia lathyris L. on the protein expression involved in intestinal metabolism, in order to illustrate the potential attenuated mechanism of Euphorbia lathyris L. processing. Differentially expressed proteins (DEPs) in the intestine after treated with Semen Euphorbiae (SE), Semen Euphorbiae Pulveratum (SEP) and Euphorbiae Factor 1 (EFL₁) were identified. The bioinformatics analysis including GO analysis, pathway analysis, and network analysis were done to analyze the key metabolic pathways underlying the attenuation mechanism through protein network in diarrhea. Western blot were performed to validate selected protein and the related pathways.

Results

A number of differentially expressed proteins that may be associated with intestinal inflammation were identified. They mainly constituted by part of the cell. The expression sites of them located within cells and organelles. G protein and Eph/Ephrin signal pathway were controlled jointly by SEP and SE. After processing, the extraction of SEP were mainly reflected in the process of cytoskeleton, glycolysis and gluconeogenesis.

Conclusions

These findings suggest that SE induced an inflammatory response, and activated the Interleukin signaling pathway, such as the Ang/Tie 2 and JAK2/ STAT signaling pathways, which may eventually contribute to injury result from intestinal inflammatory, while SEP could alleviate this injury by down-regulating STAT1 and activating Ang-4 that might reduce the inflammatory response. Our results demonstrated the importance of Ang-4 and STAT1 expression, which are the target proteins in the attenuated of SE after processing based on proteomic investigation. Thus iTRAQ might be a novel candidate method to study scientific connotation of hypothesis that the attenuated of SE after processing expressed lower toxicity from cellular levels.

     

Chemostat modeling of Escherichia coli persistence in conventionalized mono-associated and streptomycin-treated mice

We have previously shown that Escherichia coli BJ4 has similar doubling time in mice that are mono-associated (having only the inoculated E. coli BJ4) or streptomycin-treated (having mainly gram-positive bacteria plus the inoculated E. coli BJ4). We also showed that when the mice were conventionalized (fed cecum homogenate from conventional mice or ones with a complete microbial flora), the introduction of complete flora in both cases increased the in vivo doubling time, while decreasing the colony counts in fecal samples. To determine whether the increase in doubling time could explain the decrease in colony counts, we analyzed our previous results by a chemostat model. The analysis shows that the increasing doubling time alone is sufficient to explain the decrease in colony counts in mono-associated mice, but not in the streptomycin-treated mice. The observed decreasing rate in colony counts in streptomycin-treated mice is slower than predicted. Furthermore, whereas the model predicted a decrease to extinction in both mice, the E. coli persist at a frequency 10-80 times higher in streptomycin-treated mice than in mono-associated mice. Thus, while a chemostat model is able to explain some of the population dynamics of intestinal bacteria in mice, additional factors not included in the model are stabilizing the system. Because we find that E. coli declines more slowly and to a higher stabilization frequency in streptomycin-treated mice, which have a more diverse flora before conventionalization, we take these results to suggest that the persistence of E. coli populations is promoted by species diversity. We propose that a mechanism for the persistence may be the presence of new E. coli niches created by keystone species in the more diverse flora.     

Gastrointestinal Bacteria of Certain Antarctic Birds and Mammals

An investigation was carried out of the aerobic gram-negative intestinal flora of 158 penguins, 30 skuas, and 66 seals from the Antarctic and sub-Antarctic zones and Phillip Island. Among penguins and seals, 17% and 11%, respectively, were devoid of aerobic enteric organisms, but microscopic examination showed the presence of other bacteria. The coliforms outnumbered the paracolons and nonlactosefermenting bacteria; irregular coliform types and Escherichia coli were predominant. The present study indicated the effect of diet on the composition of the intestinal flora of the birds and mammals examined.     

Lactobacillus casei DN-114 001 inhibits the ability of adherent-invasive Escherichia coli isolated from Crohn's disease patients to adhere to and to invade intestinal epithelial cells

Ileal lesions in 36.4% of patients with Crohn's disease are colonized by pathogenic adherent-invasive Escherichia coli. The aim of this study was to determine the in vitro inhibitory effects of the probiotic strain, Lactobacillus casei DN-114 001, on adhesion to and invasion of human intestinal epithelial cells by adherent-invasive E. coli isolated from Crohn's disease patients. The experiments were performed with undifferentiated Intestine-407 cells and with undifferentiated or differentiated Caco-2 intestinal epithelial cells. Bacterial adhesion to and invasion of intestinal epithelial cells were assessed by counting CFU. The inhibitory effects of L. casei were determined after coincubation with adherent-invasive E. coli or after preincubation of intestinal cells with L. casei prior to infection with adherent-invasive E. coli. Inhibitory effects of L. casei on adherent-invasive E. coli adhesion to differentiated and undifferentiated intestinal epithelial cells reached 75% to 84% in coincubation and 43% to 62% in preincubation experiments, according to the cell lines used. Addition of L. casei culture supernatant to the incubation medium increased L. casei adhesion to intestinal epithelial cells and enhanced the inhibitory effects of L. casei. The inhibitory effects on E. coli invasion paralleled those on adhesion. This effect was not due to a bactericidal effect on adherent-invasive E. coli or to a cytotoxic effect on epithelial intestinal cells. As Lactobacillus casei DN-114 001 strongly inhibits interaction of adherent-invasive E. coli with intestinal epithelial cells, this finding suggests that the probiotic strain could be of therapeutic value in Crohn's disease.     

凝结芽胞杆菌TBC 169株对肠道致病菌的抑菌作用

目的 研究凝结芽胞杆菌TBC 169株对大肠埃希菌、痢疾志贺菌、伤寒沙门菌、普通变形杆菌、铜绿假单胞菌和金黄色葡萄球菌的抑制作用。方法 先将大肠埃希菌、痢疾杆菌等6种菌分别进行单独培养,测定不同培养时间内的pH和活菌数,然后将凝结芽胞杆菌TBC 169株分别和致病菌进行混合培养,再测pH和活菌数,并与单独培养时的测定情况进行比较。结果 凝结芽胞杆菌TBC 169株对大肠埃希菌、痢疾志贺菌、伤寒沙门菌等6种菌均有明显的抑制作用,尤其是对伤寒沙门菌和铜绿假单胞菌的抑制作用更强。结论 凝结芽胞杆菌TBC 169株对肠道致病菌有显著的抑制作用。