Systemic Listeria monocytogenes infection and concurrent pleural mesothelioma in a cat

Herein we describe a rare case of systemic Listeria monocytogenes infection with concurrent pleural mesothelioma in a stray cat that was found dead and submitted for autopsy. Gross pathology changes consisted of thoracic clear yellow fluid admixed with suspended fibrin strands; clear-to-tan, variably sized, <3 mm diameter pulmonary nodules; and enlargement of the submandibular, retropharyngeal, and prescapular lymph nodes. Histologic changes consisted of extensive areas of suppurative inflammation and necrosis with mineralization that partially effaced the pulmonary parenchyma and lymph nodes. Random, distinct necrotic foci were present throughout the hepatic parenchyma. Extending from the pleura, within perinecrotic alveolar spaces, and infiltrating the submandibular, retropharyngeal, and prescapular lymph nodes were dense sheets of neoplastic epithelioid cells with moderate pleomorphism and occasional karyomegaly and multinucleation. Neoplastic cells exhibited immunolabeling for pancytokeratin AE1/AE3 and vimentin, consistent with pleural mesothelioma. Aerobic bacterial culture of lung yielded heavy growth of L. monocytogenes. Immunohistochemistry (IHC) for L. monocytogenes revealed clusters of bacteria in the lung, lymph node, and liver. Pathologic changes were consistent with systemic listeriosis, confirmed by bacterial culture and IHC, and concurrent pleural mesothelioma.     

Development of A Dual Real-time PCR for the Rapid Detection of Listeria monocytogenes

To establish a rapid assay for Listeria monocytogenes(LM) detection,a Real-time PCR method was developed targeting iap gene of LM.The results showed that the test for 15 bacteria strains,only LM was positive,indicated that the method had high specificity.In addition,the sensitivity of Real-time PCR was 6.5 CFU/mL.Stability and reproducibility of the test showed that the coefficient of variation for the same sample repeat the Ct values were less than 2%.Furthermore,a total of 3 positive samples for LM were detected from 139 clinical samples by the method,which was in accordance with the testing result by GB 478930-2010 standard detection protocol.Therefore,the Real-time PCR method provides a novel rapid,sensitive and good repeatability detection method for LM infection.     

Incidence of Pathogenic Microorganisms in Aquacultured Rainbow Trout (Oncorhynchus mykiss)

ABSTRACT

Quantitative levels of six known pathogens (Listeria monocytogenes, Clostridium botulinum, Salmonella species, Vibrio cholerae, Yersinia enterocolitica, and Y. pseudotuberculosis) and aerobic plate counts were measured at five aquaculture facilities. The farmed rainbow trout (Oncorhynchus mykiss) and trout fillets were sampled at two different growing seasons to monitor for microbial hazards. Listeria spp. was identified in both whole trout and trout fillets from all five facilities sampled from both growing seasons. Presumptive Clostridium botulinum spores were also identified from all five facilities for both seasons. The growing season did not affect pathogen levels and there was no evidence that any one aquacultural system was superior to the others. Salmonella spp., Vibrio cholerae, and Yersinia spp. were not isolated from any of the trout samples analyzed.     

抗李斯特菌特异单抗试剂的研制及应用

用１％福尔马林灭活单核细胞增生李斯特菌（Ｌｉｓｔｅｒｉａｍｏｎｏｃｙｔｏｇｅｎｅｓ）Ｇ１９５１３０ｍｉｎ制成免疫原免疫ＢＡＬＢ／ｃ小鼠，利用淋巴细胞杂交瘤技术，获得３株高度特异的针对单核细胞增生李斯特菌、无害李斯特菌和格氏李斯特菌的单克隆抗体，分别命名为ＬＪ１０Ａ、ＬＢ５、ＬＭ１１。选择其中１株ＬＪ１０Ａ作为包被抗体和酶标抗体，建立了快速、敏感、特异的检测该菌的单抗夹心ＥＬＩＳＡ方法。该方法对单核细胞增生李斯特菌的最小检出量为５×１０５，模拟样品能检出５００ｃｆｕ／ｋｇ样品，且４０ｈ内能报告结果。通过检测２４０份肉样和８５０份奶样并与常规方法平行相比较，该方法的敏感性和特异性分别达到１００％和９６．９％。     

新疆绵羊致病株李氏杆菌种型鉴定与分析

采用生化反应、溶血试验、致病力试验和PCR方法对分离的新疆5株绵羊致病株李氏杆菌90SB1、90SB2、90SB5、90SS1和125SL进行了种的鉴别测定,并用RAPD技术对这5株李氏杆菌及标准株李氏杆菌进行了初步分型。结果表明,5株绵羊致病株(野毒株)在生化反应、培养特性、溶血性、致病性及溶血素基因特异性等方面表现高度的一致性,属于同一种LM。RAPD实验表明这5株LM指纹图谱相同,属于同一个型。而且其致病性LM与标准LM对照株(从食品中分离到)指纹图谱差异显著,属于不同型。     

产单核细胞李斯特菌溶血素O单克隆抗体的制备与鉴定

【目的】制备抗产单核细胞李斯特菌溶血素O(LLO)的特异性单克隆抗体。【方法】用LLO重折叠的原核表达产物LLO-his免疫Balb/c小鼠,取其脾细胞,与骨髓瘤细胞在PEG4000作用下融合,经间接ELISA法筛选、多克隆及单克隆分离出阳性细胞株后,再用体内诱生腹水法大量制备单克隆抗体。用辛酸-硫酸铵沉淀法纯化单克隆抗体,间接ELISA法测定其效价及相对亲和常数;用HBT单克隆抗体亚类鉴定试剂盒鉴定抗体亚型;常规方法制备染色体,观察细胞株染色体数目及标志染色体;Western blot检测抗体的特异性。【结果】获得了2株稳定分泌抗LLO单克隆抗体的杂交瘤细胞系,分别命名为3F5-G3和2B4-C8,其腹水效价分别为1∶(1×105)和1∶(1×107);染色体分别为97±5和93±8条,且观察到标志染色体;相对亲和常数分别为0.49和0.26μg/mL;抗体亚类均为IgG1,轻链均为κ链。特异性鉴定结果表明,2种单克隆抗体均可与LLO蛋白发生特异性反应,而与载体蛋白不发生反应。【结论】获得了抗LLO的特异性单克隆抗体。     

单核细胞增生性李斯特菌mpl基因的克隆及其原核表达载体的构建

研究对单增李斯特菌Mpl蛋白进行了基因克隆及表达载体的构建.通过PCR方法对标准株单增李斯特菌菌株mpl基因进行扩增,并将其克隆至pET32 a(+)上构建表达载体.经DNA序列测定分析,扩增出的基因与GenBank发表的单增李斯特菌mpl基因序列EF183452和EF183453的同源性为99.7%,氨基酸同源性为1...     

食品中单增李斯特菌检测技术研究进展

单增李斯特菌是一种重要的人畜共患食源性致病菌,如何有效控制食品(尤其是即食食品)中的单增李斯特菌,是食品安全的重要任务,其中快速、准确的检测技术是关键因素之一.作者对单增李斯特菌的传统检测法、免疫学检测法和分子生物学检测法进行综述,并对目前国内单增李斯特菌检测过程中所存在的问题进行探讨,以期为今后的研究提供参考.     

新疆绵羊致病株李斯特杆菌分离与鉴定

本研究采用生化反应，溶血试验，致病力试验，PCR方法对分离的新疆5株绵羊致病株李斯特杆菌90SB1，90SB2，90SB5，90SS1，125SL进行了种型的鉴别测定，并用RAPD技术对这5株李斯特杆菌及标准株李斯特杆菌进行分型。试验结果，五株绵羊致病株（野毒株），在生化反应，培养特性，溶血性，致病性及溶血素基因特异性等方面表现高度的一致性，属于同一种LM。RAPD实验表明此5株LM指纹图谱相同，属于同一个型。此5株致病性LM与标准LM对照株（从食品中分离到）指纹图谱差异显著，属于不同型。     

Kinetics of Interferon-Gamma Production and its Comparison with Anti-Listeriolysin O Detection in Experimental Bovine Listeriosis

The kinetics of the production of interferon gamma (IFN-) in whole blood culture and its comparison with anti-listeriolysin O (ALLO) detection by ELISA were studied during oral infection of calves with Listeria monocytogenes. Culture filtrate antigen (CFA), listeriolysin O (LLO), and sonicated antigen (SA) were used to prime the peripheral blood mononuclear cells (PBMCs) and the plasma from orally infected calves. IFN- and ALLO appeared as early as day 7 of an oral infection. IFN- was detected earlier with LLO than with SA. The Max50 interleukin (IL-2) activity and IFN- estimated in the culture supernatant from PBMCs primed in vitro with different antigens of L. monocytogenes revealed high induction of IL-2 and IFN- by CFA, LLO and live antigen. IFN- assay and ALLO detection were used for testing cases of repeat breeding in dairy cattle. It appeared that detection of IFN- employing LLO can be used to diagnose listerial infections.