齿龈内阿米巴形态学的观察

目的 :观察齿龈内阿米巴滋养体的形态。方法 :从口腔疾病患者牙周组织或龈隙挑取渗出物 ,生理盐水涂片后镜下观察其形态并测量大小。结果 :齿龈内阿米巴滋养体活体大小平均为 14 .93× 12 .4 2μm ,形态呈圆形、长椭圆形及不规则葫芦形等。伪足透明 ,呈指状、舌状 ,球形及草帽形等不规则形态 ,其伪足伸缩变化较大 ,运动无一定方向。与溶组织内阿米巴滋养体形态有很多相似之处。结论 :全面观察了其运动方式及其形态变化特点 ,因取材方便 ,建议在寄生虫学教学实习中代替溶组织内阿米巴滋养体 ,观察活体阿米巴运动     

上海市综合性医院腹泻患者中溶组织内阿米巴感染现状调查

目的 了解综合性医院腹泻患者溶组织内阿米巴感染现状,为防治工作提供科学依据。方法 选择上海市3所综合性医院肠道门诊,采集门诊腹泻患者新鲜粪便和血清,分别采用生理盐水涂片法和碘液染色法、免疫层析法、ELISA法进行检测,以了解腹泻患者溶组织内阿米巴感染状况,并对感染者特征进行分析。结果 检测腹泻患者粪便样本 1 015份, 检出溶组织内阿米巴原虫病原学阳性36份, 总阳性率为3.55%。3所医院腹泻患者病原学阳性率间差异无统计学意义（P > 0.05）,溶组织内阿米巴阳性者性别、年龄、职业和文化程度分布差异均无统计学意义（P均 > 0.05）,脓血便中溶组织内阿米巴阳性率显著高于稀便和水样便（P均 < 0.01）。7-9月为发病高峰。88.90%的阳性者有腹痛,75.00%和22.23%的阳性者粪便查见白细胞和红细胞。试剂条法检测溶组织内阿米巴粪抗原阳性率为8.18%（83/1 015）,ELISA 法检测溶组织内阿米巴IgG抗体阳性率为7.12%（48/675）。结论 夏秋季是溶组织内阿米巴感染高发季节,应加强监测;脓血便中溶组织内阿米巴检出阳性率较高,联合应用多种检测手段能提高检出率。     

Invasive amebiasis in men who have sex with men, Australia

Entamoeba histolytica is a pathogenic ameba that has recently been recognized as an emerging pathogen in men who have sex with men (MSM) in Asia-Pacific countries where it is not endemic, i.e., Japan, Taiwan, and Republic of Korea. We report locally acquired invasive amebiasis in Sydney, Australia, exclusively in MSM.     

齿龈内阿米巴的超微结构与溶酶体酶细胞化学研究

目的　研究齿龈内阿米巴的细胞器与功能 ,探讨虫体与宿主细胞的关系。方法　用透射电镜结合电镜酶细胞化学技术观察虫体细胞超微结构 ;将虫体与口腔上皮细胞孵育 ,观察虫体对上皮细胞的粘附。结果　虫体及其伪足呈多形态 ;胞质内细胞器主要为泡状和管状的溶酶体、一些滑面内质网 ,以及丰富的糖原颗粒 ;溶酶体标志酶CMPase显示溶酶体酶丰富 ;可见虫体粘附于上皮细胞表面和小伪足伸入上皮细胞微绒毛间。结论　虫体的溶酶体水解酶消化作用及虫体伪足的机械作用对宿主牙周上皮组织的损伤 ,是虫体的致病机制之一。     

Diagnostic methods for differentiation of Entamoeba histolytica and Entamoeba dispar in carriers: performance and clinical implications in a non-endemic setting

Unpreserved faecal samples, suspected to contain Entamoeba histolytica/Entamoeba dispar cysts or trophozoites on the basis of microscopic examination, and serum samples from 416 patients were collected in a prospective study to determine whether stool antigen assays and detection of antibodies in serum are reliable methods to distinguish between carriers of E. histolytica and E. dispar in comparison to the reference test: real-time PCR. In 283 patients (68%) DNA of E. histolytica or E. dispar was amplified by real-time PCR: 6 patients with amoebic colitis (2%), 19 carriers of E. histolytica (6.7%), and 258 carriers of E. dispar (91.2%). In 133 patients (31%) no DNA of E. histolytica or E. dispar could be amplified in the stool samples. This patient group was used as control for the evaluation of diagnostic tests. Using real-time PCR as a reference test, the sensitivity and specificity of (1) the Entamoeba test for the diagnosis of E. histolytica/E. dispar carrier were 59% and 98%, (2) E. histolytica II for the diagnosis of E. histolytica carrier was 71% and 100%, and (3) serology for the diagnosis of E. histolytica infection was 83.3% and 95.2%, respectively. Applied to carriers that did not originate from an endemic country the sensitivity of serology for E. histolytica infection was 90% and specificity was 98.8%. In comparison to real-time PCR the performances of Entamoeba test and E. histolytica II lacked sensitivity for a reliable diagnosis of E. histolytica/E. dispar infection in a non-endemic setting. In carriers of E. histolytica/E. dispar from non-endemic countries the high specificity of serology can be used to establish the diagnosis of E. histolytica infection if antibodies are present.     

Evaluation of the Roche LightMix Gastro parasites multiplex PCR assay detecting Giardia duodenalis,Entamoeba histolytica,cryptosporidia, Dientamoeba fragilis,and Blastocystis hominis

ObjectivesMultiplex PCR assays offer highly sensitive and specific tools for the detection of enteric pathogens. This prospective study aimed at comparing the novel Roche LightMix Modular Assay Gastro Parasites (LMAGP) detecting Giardia duodenalis, Entamoeba histolytica, Cryptosporidium spp., Blastocystis hominis, and Dientamoeba fragilis with routine laboratory procedures.MethodsStool specimens (n = 1062 from 1009 patients) were consecutively examined by LMAGP, R-Biopharm Ridascreen enzyme immunoassays (EIAs) detecting G. duodenalis or E. histolytica/dispar, and microscopy of wet mounts. Discrepant results were analysed by in-house PCR.ResultsD. fragilis or B. hominis were detected by LMAGP in 131 (14.4%) and 179 (19.9%; 16 samples positive by microscopy; p < 0.0001) of 909 samples, respectively. Of 918 samples analysed for Cryptosporidium spp., six were positive by LMAGP (three could be confirmed by Kinyoun staining and one by in-house PCR). G. duodenalis was detected by LMAGP, EIA, or microscopy in 20, 16, or 9 of 1039 stool samples, respectively; all four samples missed by EIA were confirmed by in-house PCR. In total, 938 stool samples were analysed for E. histolytica/dispar. Nine of ten EIA-positive samples were negative by LMAGP but positive by in-house PCR for E. dispar. One E. histolytica infection (positive by both LMAGP and in-house PCR) was missed by EIA and microscopy. Parasites only detected by microscopy included Enterobius vermicularis eggs (n = 3) and apathogenic amoebae (n = 27).ConclusionsThe data call for routine use of multiplex PCR assays for the detection of enteric protozoan parasites in laboratory diagnostics.     

Entamoeba histolytica sequences and their relationship with experimental liver abscesses in hamsters

The purpose of the present paper was to analyse the association between sequences of Entamoeba histolytica and their relationship with the development of hepatic abscesses in hamsters, using a complementary DNA library for E. histolytica. From the sequences obtained, we designed oligonucleotides for amplification by PCR. Trophozoites were isolated from faeces of 11 patients in whom cysts from E. histolytica were identified, and these trophozoites were then subjected to monoaxenic culture. Then 1×10⁵ trophozoites were inoculated into hamster liver, with three hamsters used for every culture. Sequences were obtained for ubiquitin, lectin surface precursor, replication factor MCM3 and surface antigen. The associations between sequences and hepatic abscesses were: 11/11 for ubiquitin, 9/11 for lectin precursor, 4/11 for replication factor and 1/11 for surface antigen. These results suggest that ubiquitin could be an important protein involved in the mechanism of E. histolytica invasion.     

齿龈内阿米巴的致病作用与致病机制的研究

在注射免疫抑制剂 1周后的大白鼠龈缘涂抹齿龈内阿米巴 (Emtamoebagingivalis ,E .g .) ,5天后 ,牙龈组织出现溃疡、牙周脓肿形成、脓液查见活E .g .、牙槽骨吸收等牙周炎病症。电镜术与生化分析发现 :E .g .伪足活跃、有丰富的溶酶体 ,所含水解酶与ACP显著较健康组高 (P <0 0 1) ,可使牙周组织溶解与受损。SOD较健康组显著性低 (P <0 0 1) ,MDA显著性增高 (P <0 0 1) ,说明E .g .感染产生较多氧自由基可使细胞膜受损 ,加上口腔共生菌的协同作用使免疫力低下的宿主发生牙周炎。     

用限制性内切酶分析溶组织内阿米巴的致病性

用SH-3、SH-5、SH-6、SH-7和SH-85株溶组织内阿米巴的DNA增殖35个周期,将其基因DNA用内切酶HinfⅠ和EcoT22Ⅰ进行消化后,作琼脂糖凝胶电泳分析,显示,5株虫株DNA经35个循环周期后产生531-bp的产物;经HinfⅠ消化后,SH-3、SH-5、SH-6和SH-7的基因DNA产生3个相同的片段,而显示其均与非致病性虫株SAW142的电泳谐完全相同;而SH-8基因DNA的电泳谱与致病性虫株SAW408的电泳谱一致,而用EcoT22Ⅰ消化结果也显示SH-8的图谱与致病性虫株SAW408的相同,证实了从包囊携带者和有发热、腹泻而无脓血便患者粪便中分离的虫株均属于非致病性虫株,从有发热、腹泻、脓血便的急性阿米巴痢疾患者粪便中分离到的虫株属于致病性虫株,均与酶株群分析相一致。提示,应用多聚酶链反应和限制性内切酶消化基因DNA来检测溶组织内阿米巴的基因型是十分有意义的。     

Antibodies to the serine rich Entamoeba histolytica protein (SREHP) prevent amoebic liver abscess in severe combined immunodeficient (SCID) mice

Amoebic liver abscess caused by Entamoeba histolytica is a major cause of morbidity and mortality worldwide. We used mice with severe combined immunodeficiency (SCID mice) to study the role of antibody in protection from amoebic liver abscess, and to identify protective antigens of E. histolytica. Antisera to recombinant versions of two major surface antigens of E. histolytica, the serine rich E. histolytica protein (SREHP) and the 170 kDa adhesin were used in this study. We found that 100% of SCID mice passively immunized with antiserum to the recombinant SREHP molecule were protected from developing amoebic liver abscess after intrahepatic challenge with virulent E. histolytica trophozoites. In contrast, preimmune serum, antiserum to a portion of the 170 kDa adhesin, and antiserum to the trpE fusion partner of SREHP did not protect SCID mice from amoebic liver abscess. Our study demonstrates that antibodies to a recombinant version of the amoebic SREHP molecule can protect against amoebic liver abscess, and suggest the recombinant SREHP molecule should be considered as a possible vaccine candidate to prevent amoebic liver abscess.