Fingerprinting of Salmonella enterica subsp. enterica serovar Enteritidis by ribotyping

Objective: To carry out an epidemiologic evaluation of Salmonella enterica subsp. enterica serovar Enteritidis outbreaks in households and small communities by means of rRNA gene restriction pattern analysis (ribotyping).
Method: One hundred Enteritidis isolates dating from 1989 to 1994 which could be allocated epidemiologically to different sources or to small community outbreaks were investigated with ribotyping, a fingerprinting method in which bacterial DNA is hybridized with the biotin-labeled plasmid pKK 3535 containing a ribosomal RNA operon of Escherichia coli to determine the ribosomal RNA gene restriction patterns.
Results: Four different ribotyping patterns were found with the restriction endonuclease Sma I and nine with Sph I. Ribotypes of isolates which could be allocated epidemiologically to a common source usually corresponded. Almost 60% of the Enteritidis infections had the ribotyping pattern Sph I-A. In contrast, this pattern was not found in any of the five Enteritidis strains isolated in 1989. The suspicion that Enteritidis phage type 4 infections are caused by consumption of insufficiently heated eggs is supported by the fact that the ribotyping pattern Sph 1-A was found in isolates from eggs and from human specimens.
Conclusions: As patterns Sph I-A and Sma I-J appeared in 58% and 75% of the isolates, respectively, ribotyping cannot be used for the differentiation between various outbreaks with these two patterns. In cases where the Enteritidis strains showed less frequent patterns, ribotyping seems to be a practical tool for the identification of infection chains. In addition newly appearing ribotyping patterns can give information about the epidemiologic development of Enteritidis infection.     

内毒素核心糖脂单克隆抗体的血清学反应性及保护作用的初步研究

以S.minnesota R595菌为免疫原,通过细胞融合获得8株分泌抗核心糖脂单抗的杂交瘤细胞系。对其中的两株代表性单抗2D6E7和3H4 2F7的血清学反应性以及在小鼠Hb/Mu腹腔感染模型中的保护作用进行了初步研究。菌体吸收试验和间接免疫荧光试验(ⅡF)表明,单抗能与多种革兰氏阴性杆菌(GNB)产生交叉反应,并且光滑型GNB的煮沸菌体荧光染色呈阳性,活菌染色呈阴性。保护性试验结果表明,3H4 2F7单抗能显著提高S.minnesota(野生菌株),鼠伤寒杆菌和E.Coli等光滑型GNB攻击的小鼠存活率(P<0.05),显示出抗核心糖脂单抗的良好交叉保护作用。若攻击前、后2h或攻击同时输入单抗3H4 2F7,对光滑型GNB的感染均有明显保护效果(P<0.05);2D6 E7单抗未表现有保护活性。     

安顺市区沙门氏菌环境污染调查

在贵州省安顺市１９８５年水型伤寒爆发流行后，为调查该市环境中沙门氏菌污染情况，我站于１９８６～１９８８年对市区所属医院和贯城河污水及部分食物的沙门氏菌进行了监测，共采集污水及食品６１９份，沙门氏菌阳性率为４１．８４％，分属Ａ、Ｂ、Ｃ、Ｄ、Ｅ１五个群１２个血清型，伤寒沙门氏菌经Ｖｉ噬菌体分型为Ｍ１型。纸片药敏试验为多重性耐药菌株。阐明了沙门氏菌流行的部分传播媒介途径。     

用化学发光自显影技术快速检测鸭沙门氏菌

应用我室建立的化学发光自显影技术检测鸭沙门氏菌。用酶标抗体与硝酸纤维素膜上固定的细菌结合,再同发光底物溶液作用,使X线胶片感光,根据胶片上的黑斑进行半定量,可检出100个菌。其检测特异性好,约2小时即可出报告。     

单核吞噬细胞应答伤寒沙门菌的实验研究

目的 研究单核吞噬细胞应答伤寒沙门菌的机理。方法 采用体外培养的PMA分化的THP－1细胞，检测其内化和杀伤胞内伤寒沙门菌的活性，以及伤寒沙门菌诱导PMA分化的THP－1细胞产生TNF－α和IL－12的情况。结果 PMA分化的THP－1细胞内化和杀伤Vi阴性伤寒沙门菌的活性明显高于内化和杀伤Vi阳性伤寒沙门菌的活性。IFN－γ明显中此活性。伤寒沙门菌诱导PMA分化的THP－1细胞可以产生一定量的TNF－α和IL－12，然而，IFN－γ活化的PMA分化的HTP－1细胞产生TNF－α和IL－12的量明显增加。结论 伤寒沙门菌在单核吞噬细胞中的存活可能与Vi抗原的存在有关；IFN－γ在调节机体细胞免疫，防循伤寒沙门菌感染中起着重要的作用。     

幽门螺杆菌尿素酶减毒鼠伤寒杆菌疫苗诱导小鼠粘膜免疫应答的研究

目的:观察口服减毒鼠伤寒杆菌活菌重组疫苗后小鼠的粘膜免疫应答状况。方法:将已构建成功的表达幽门螺杆菌(H.pylori)尿素酶B亚单位(UreB)的重组减毒鼠伤寒杆菌SL3261/pTC01-UreB口服免疫Balb/c小鼠,12周后检测肠液和血清中的特异性抗体反应。结果:疫苗组小鼠的肠液和血清中可分别检测到针对UreB的特异性抗体IgA和IgG,病理学检查显示疫苗组小鼠较对照组小鼠胃粘膜炎症程度差异无统计学意义。结论:表达H.pyloriUreB的减毒鼠伤寒杆菌SL3261/pTC01-UreB能够诱导小鼠产生抗H.pylori的粘膜免疫,可用作抗H.pylori感染的口服疫苗。     

Intraperitoneal infection with Salmonella abortusovis is partially controlled by a gene closely linked with the Ity gene.

The aim of the present study was to determine whether the Ity gene, which controls the resistance to S. typhimurium infection in mice, also governs the resistance to S. abortusovis, a serotype specific for goat and sheep. During either i.v. or i.p. infection, BALB/c mice (Itys) were not able to control the growth of S. abortusovis and eventually died from infection. In contrast CBA (Ityr) or (C.CB)F1 (Ityr/s) mice were able to control the growth of these bacteria. Using congenic C.D2 Ityr mice, we found that the gene controlling resistance to S. abortusovis was tightly linked to the Ity gene on chromosome 1. Furthermore, in the spleen and the liver of backcross BALB/c x (CBA x BALB/c) mice, the S. abortusovis resistance phenotype cosegregated with the two alleles of the Len-1 gene, a gene tightly linked to the Ity gene. By contrast, in these backcross mice, the level of infection of the peritoneal cavity, the site of inoculation, did not correlated with the Len-1 phenotype of the animal. These results provide evidence that after i.p. inoculation the control of S. abortusovis growth in the spleen and the liver is controlled by the Ity gene, but also suggest that additional gene(s) regulate the number of bacteria at the site of inoculation.     

Infected chronic hematoma mimicking soft tissue neoplasm

A rare case of an infected chronic hematoma in a patient with immunodeficiency syndrome mimicking a soft tissue neoplasm is presented. There are few reported cases of hematogenous infection of chronic hematomas, which be difficult to differentiate from soft tissue neoplasms.     

有机磷农药分子片段诱发沙门氏菌回复突变的计算机辅助评价

用计算机辅助分子片段评价程序分析了５９种有机磷化合物诱发沙门氏菌回复突变的资料。发现：有机磷诱发沙门氏菌回变与带甲基的分子片段有关，而带乙基分子片段的有机磷的阳性概率极低；磷酰基上的氧原子似有增强诱变性的作用，硫代磷酰基上的硫原子则似有减弱作用。提示：在这些相关片段中，甲氧磷酰基片段与有机磷诱发沙门氏菌回变相关，可推荐为有机磷诱发阳性的特征描述符；而乙基硫羰磷酰基阳性的概率极低，为阴性结果的描述符。     

Typhoid fever due to a Salmonella typhi strain of reduced susceptibility to fluoroquinolones

Objective: To report a case of typhoid fever contracted in Portugal in 1994 due to a Salmonella typhi isolate which had reduced susceptibility to fluoroquinolone (MIC 1 mg/L of ciprofloxacin) and high level resistance to nalidixic acid (MIC ≥56 mg/L).
Methods: Molecular studies of reduced susceptibility to fluoroquinolones comprised complementation tests with a wild-type allele and sequencing directly from PCR products of the gyrA gene.
Results: Complementation tests and DNA sequencing showed that a mutation occurred in the gyrA gene of this clinical isolate, resulting in a substitution of phenylalanine for serine at position 83 of GyrA.
Conclusions: Because quinolones may be regarded as a treatment of choice in typhoid fever, it seems important now to recommend cautious use of these drugs as first-line therapy and possibly use of nalidixic acid resistance as a marker for detection of 'first-step' resistance to fluoroquinolones in S. typhi.