鼠伤寒沙门氏菌对某些理化因子抗力的研究

测试了热、紫外线、臭氧、过氧乙酸、碘伏、来苏儿、新洁尔灭、乙醇对鼠伤寒沙门氏菌的杀灭作用。在所试剂量下，各种因子对该菌均有一定杀灭作用，但杀灭的效果不全一致。不同株鼠伤寒沙门氏菌间，或鼠伤寒沙门氏菌与大肠杆菌之间，对各种因子的耐受力可互有强弱。     

Protective role of Hemidesmus indicus R. Br. root extract against Salmonella typhimurium-induced cytotoxicity in Int 407 cell line

The present investigation deals with the effect of the chloroform fraction composed of sterols and fatty acids isolated from Hemidesmus indicus root extract (CHI) on Salmonella enterica serovar Typhimurium (S. typhimurium)-induced cytotoxicity in a human intestinal epithelial cell line (Int 407). The optimum dose was fixed as 100 microg/mL for CHI against S. typhimurium, which was quite safe for Int 407 cells as the CD(50) concentration (50% cell death) of CHI was determined to be 500 microg/mL in the Int 407 cell line. CHI-treated S. typhimurium were 10-fold less cytotoxic and 40% less adherent to host cells than wild-type. Treatment of CHI significantly abrogated the invasion ability to 10- to 15-fold in S. typhimurium. The cells infected with CHI-treated S. typhimurium had a comparable viability to uninfected cells in the epithelial cell detachment assay. Immunofluorescence showed the CHI-treated bacteria were unhealthy and shrunken rods in comparison with the wild-type bacteria; those were firmly attached and invaded to deceased and hypertrophoid Int 407 cells. Transmission electron micrographs of Int 407 cells infected with wild bacteria showed a coat of adherent and invaded bacteria completely occupying the cytoplasm with characteristic Salmonella-containing vacuoles (SCV). Both necrotic and apoptotic type of cell death were observed in cells infected with wild-type bacteria, whereas most of the cells infected with treated bacteria were normal in morphology and a few had invaded bacteria, but the typical proliferated SCV was not observed in cells infected with CHI-treated S. typhimurium. In summary, the sterols and fatty acids present in CHI may be capable of taming S. typhimurium by suppressing its cytotoxic activity in an intestinal epithelial cell line.     

鼠伤寒脂多糖表位模拟位的筛选

目的获得模拟脂多糖抗原表位的噬菌体环状展示肽。方法用抗鼠伤寒菌脂多糖单克隆抗体2F4为靶分子,亲和筛选噬菌体随机环七肽库,双夹心ELISA及特异性抗原抑制试验鉴定阳性克隆。结果经三轮筛选,随机挑选38个克隆,其中34个克隆显示与2F4结合。鼠伤寒沙门氏菌脂多糖可抑制噬菌体克隆与2F4结合,所有克隆的半数抑制浓度为(0.125~0.250)μg/ml。挑选10个克隆测序并推导氨基酸序列,其中7个克隆出现P-X-WAS-X-W保守序列;10个序列中非极性氨基酸含量平均值为71.4%。结论噬菌体展示环七肽可模拟鼠伤寒沙门氏菌脂多糖抗原表位。     

Chemico/biological investigation of contaminated sediment from the hamilton harbour area of Western Lake Ontario

Highly contaminated sediment from the Hamilton Harbour area of western Lake Ontario was examined using a bioassay-directed fractionation methodology. A sediment sample was extracted using a Soxhlet apparatus and the resulting extract was fractionated into compound classes using an alumina clean-up step and high performance liquid chromatographic techniques. The resulting fractions were subjected to bioassays using TA98- and TA100-like strains modified by the inclusion of genes for the activating enzymes nitroreductase and O-acetyl-transferase. The majority of the mutagenic activity displayed by the sample extract was found to be present in the fraction containing the polycyclic aromatic hydrocarbons (PAH). Extracts of the PAH-containing fraction displayed dramatically higher responses with the TA100 type strains with metabolic activation. Further separation of the PAH-containing fraction showed the majority of the biological activity coeluted with PAH having molecular masses of 276, 278, and 302 amu. © 1993 Wiley-Liss, Inc.     

醋氯芬酸的鼠伤寒沙门氏菌诱变性试验

应用鼠伤寒沙门氏菌回复突变试验研究了醋氯芬酸的诱变作用。试验选用TA97,TA98,TA100,TA102菌株。当醋氯芬酸的浓度在1,10,100,1000,4000μg/皿,无论加或不加S_9混合物时其对四株沙门氏菌株的回复突变作用均为阴性。结果表明,醋氯芬酸在体外对原核细胞无诱变作用。     

泰城饮食行业人员沙门氏菌带菌情况调查

对泰城1986～1989年18873名饮食行业人员沙门氏菌带菌情况调查结果为,4年共检出沙门氏菌159株,总检出率为0.84％。血清学鉴定共分为6个群20个血清型,以B群为主,以阿哥纳血清型最多。结果说明饮食行业人员中沙门氏菌带菌者较为常见,对该类人员的卫生管理应进一步加强。     

药物在体外消除肠道杆菌携带的耐药质粒pRsT98的研究

目的 探讨用中西药在体外消除肠道杆菌携带的耐药质粒pRST98的可能性。方法 将原存在于伤寒杆菌中的耐药质粒pRST98经接合转移分别导入大肠杆菌和鼠伤寒杆菌，选用双黄连和氧氟沙星对上述3种细菌进行亚抑菌浓度的消除试验，并对实验前后的受试菌分别进行K－B纸片扩散法和最小抑菌浓度法（MIC）药敏试验及质粒电泳检测。结果 两种药物在体外未能将受式菌携带的pRST98消除；但该质粒编码的耐药标志减少；部分菌株对原有药物的耐药程度明显下降。结论 双黄连和氧氟沙星能降低pRST98宿主菌的耐药性，但药物作用后同一质粒在不同宿主菌中耐药性变化的差异，显示该质粒表达的多样性和复杂性。     

富营养预增菌液在肉制品沙门菌常规检测方法中替代效果研究

目的非选择性富营养肉汤（EB）预增菌检测肉制品沙门菌的方法建立。方法评估免疫磁珠分离（IMS）作为常规流程分离食品沙门菌的肉质控方法；比较样品经乳糖肉汤（LB）和EB两种预增液分步增菌后常规平板分离与IMS的分离效果；最终实样比较以EB为预增液的替代流程与IMS的检测敏感性。结果应用IMS检测100件用LB和134件EB分步增菌样品的阳性率没有差异（P〉0．05）；48件肉制品用EB预增的常规平板分离阳性率均高于LB，56件肉制品用EB预增液作常规平板分离的检测敏感性接近IMS（P〉0．05）。结论以EB为预增菌的肉制品沙门菌分步检测流程，节省了增菌时间。提高常规平板分离的检测敏感性。     

重组幽门螺杆菌疫苗诱导小鼠产生THL型保护性应答及免疫后胃炎

目的 研究以减毒鼠伤寒沙门氏菌为载体构建的重组幽门螺杆素酶A亚单位及过氧化氢酶、／尿素酶A亚单位融合蛋白疫苗对小鼠的免疫保护作用及相关机制。方法 将表达幽门螺杆菌(Helicobacter pylori,HP)尿素酶A亚单位(UreA)、过氧化氢酶(KatA)及尿素酶A亚单位／过氧化氢酶融合蛋白(Urea／KatA)的减毒鼠伤寒沙门氏菌(Salmonella typhimurium)分别灌胃免疫小鼠,另设单纯减毒鼠伤寒沙门氏菌免疫鼠和生理盐水免疫鼠为对照。免疫4周后以幽门螺杆菌活菌攻击,比较各组胃粘膜的幽门螺杆菌定植密度,攻击前后三清中抗幽门螺杆菌抗体IgGI,IgG2a和IgA的变化,脾脏和胃粘膜中γ干扰素(IFN-γ)和白介素4(IL-4)mRNA表达变化及胃粘膜炎症情况。结果(1)KarA及Urea／Kara组的幽门螺杆菌定植密度显下降,Urea组下降不明显。(2)和生理盐水组相比攻击前各鼠伤寒沙门氏菌免疫组IgGI,IgG2a均轻度升高而IgA无变化,攻击后各鼠伤寒沙门氏菌免疫组IgG2a升高显,KatA和Urea／KatA组尤为明显,而IgGI和IgA的升高无统计学差异。(3)胃粘膜攻击前生理盐水组无IFN-γ表达,其余各组均100％表达;攻击后生理盐水组IFN-γ轻度表达但仍明显低于各鼹伤寒沙门氏菌免疫组。IL-4在攻击前后各组均无表达。(4)脾IFN-γ和IL-4在所有组攻击前后均全部表达。(5)攻击前各组鼠胃粘膜仅有散在少量白细胞,攻击后各鼠伤寒沙门氏菌免疫组出现明显以淋巴及单核细胞浸润为特征的炎症反应。结论以减毒鼠伤察沙门氏菌为载体构建的重组幽门螺杆菌疫苗(Katk、urek/kalk)可在小鼠体内诱导出以TH1反应为主并伴随免疫后胃炎均保护性免疫应答。