Meningoencephalitis due to Listeria monocytogenes in a Young Immunocompetent Patient: Case Report with Literature Review

Meningoencephalitis secondary to Listeria monocytogenes (L. monocytogenes) mainly affects newborns, the elderly and immunocompromised people;there are extremely rare cases in which said infection occurs in immunocompetent individuals. We present the case of a young adult patient without immunocompromise, who developed meningoencephalitis due to L. monocytogenes;This case is exceptional, since it occurred in an individual outside the classic age group, in addition to not having risk factors, which is why it should be considered an atypical causal agent.

Transcriptomics reveals substance biosynthesis and transport on membranes of Listeria monocytogenes affected by antimicrobial lipopeptide brevilaterin B

Listeria monocytogenes is a worrisome food-borne pathogen threatening global food safety.Our previous study proved that lipopeptide brevilaterin B showed efficient antibacterial activity against L.monocytogenes by interacting with the cell membrane.This research further explored the antibacterial mechanism of brevilaterin B against L.monocytogenes at the sub-minimum inhibition concentration via transcriptomic analysis.Brevilaterin B induced growth inhibition rather than direct membrane lysis in L.monocytogenes at the minimum inhibitory concentration.Transcriptomic analysis showed 1779 difference expressed genes,including 895 up-regulated and 884 down-regulated genes.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that brevilaterin B influenced multiple pathways of L.monocytogenes,including peptidoglycan biosynthesis,membrane transport(ATP-binding cassette transports,ion transport),cellular metabolism(amino acid and lipid metabolism),ATP synthesis,and activation of the stress response(quorum sensing and bacterial chemotaxis).In conclusion,brevilaterin B affects gene expression related to biosynthesis,transport and stress response pathways on the membrane of L.monocytogenes.The present work provides the first transcriptomic assessment of the antibacterial mechanism of lipopeptide brevilaterin B at the gene level.

Identification of Salmonella and Listeria monocytogenes by Near-infrared Spectroscopy and PCA

Near-infrared spectra of pathogenic bacteria (salmonella and Listeria monocytogenes ) were determined, and the spectral data were analyzed by the projection discriminant analysis based on principal component analysis (PCA). The expected results were obtained. The results showed that salmonella and L. monocytogenes could be distinguished from each other by the near-infrared spectroscopy of the whole cells, cell walls or cytoplasm.

Effects of Sodium Lactate on the Survival of <i>Listeria Monocytogenes</i>, <i>Escherichia coli</i>O157:H7, and <i>Salmonella</i>spp. in Cooked Ham at Refrigerated and Abuse Temperatures

The objective of this study was to determine the effect of sodium lactate on the survival of Listeria monocytogenes, Escherichia coli O157: H7, and Salmonella spp. in cooked ham during storage at refrigerated and abuse temperatures. Cooked ham was added with 0% - 3% lactate, inoculated with a multiple-strain mixture of L. monocytogenes, E. coli O157: H7, or Salmonella spp. and stored at 4oC - 15oC for up to 35 day. The growth of the three pathogens was inhibited in ham containing 3% lactate, and no growth of E. coli O157: H7 and Salmonella spp. occurred at the lowest storage tem- peratures of 6 and 8oC, respectively. In ham containing no lactate, the average growth rates were 0.256 - 0.380 log CFU/day for L. monocytogenes at 4oC - 8oC, 0.242 - 0.315 log CFU/day for E. coli O157: H7 at 8oC - 15oC, and 0.249 - 0.328 log CFU/day for Salmonella spp. at 10oC - 15oC. The addition of 1% or 2% lactate significantly (P < 0.05) reduced the growth rates of the three pathogens, and the effect was more profound at lower temperatures. Salmonella spp. were more sensitive to the effect of lactate than L. monocytogenes and E. coli O157: H7. Polynomial models were developed to describe the growth rates of the three pathogens as affected by the lactate concentration and storage tem- perature. Results from this study demonstrate the effect of lactate on the growth of L. monocytogenes, E. coli O157: H7, and Salmonella spp. in cooked ham and indicate the effective lactate concentrations and storage temperatures that can be used to enhance the microbiological safety of ready-to-eat ham products.

Biofilm Determination of Listeria monocytogenes That Isolated from Different Sources

The study was conducted for the detection of Listeria monocytogenes bacteria from different sources （CSF and blood） obtained from patients in Pediatric hospital and from food sources like （yogurt, raw vegetables and raw milk, sausage）. Ten isolates were isolated from 150 specimens one of them from CSF and one isolate isolated from blood samples the others isolated from food specimens 6 isolates isolated from sausage and 2 from raw vegetables. Isolates were identified traditionally involved culture methods based on selective enrichment and plating followed by the characterization of Listeria spp. based on colony morphology, sugar fermentation and haemolytic properties, identification by Api listeria was done. Determine the isolates that produce biofilm by tissue culture plate method. The highest biofilm forming strains ofListeria monocytogenes isolates appear in No. （D10, El, E5 and E7） OD reading each of them is （0.13, 0.09, 0.11 and 0.19） respectively, the lowest or poor biofilm forming strains appear in No. （D11, D12, E2, E3, E4 and E6） that optical density （OD） reading are （0.04, 0.03, 0.05, 0.04, 0.05 and 0.03） respectively by comparing with control prepared in well （A12） that stained by crystal violate without putting any isolates and the OD reading is （0.003）. Confirmation by PCR was done only for four isolates that produce biofilm （D10 and El） that obtained from CSF and blood sample and for （E5 and E7） that obtained from food samples.

实验动物中单核细胞增生性李氏菌(Listeria monocytogenes)分离方法的研究

以一种新的培养基用于斜光照射法快速鉴别李氏菌,它优于加入抑制剂的分离培养基,具有快速、准确的特点。通过对几种选择性增菌液的比较,发现CRT的增菌效果最好.它与新的分离平板结合使用,分离灵敏度比原方法提高5～10倍。同时简化了内脏匀浆分离李氏菌的方法。并用此法和改进后的CRT方法对人工感染的动物进行了分离,结果证实这两种方法切实可行.对北京地区几个单位的动物也进行了分离,结果为阴性。

感染LM小鼠巨噬细胞外泌体的转录组测序及差异表达miRNA特征分析

[目的]分离和鉴定感染单核细胞增生李斯特菌(Listeria monocytogenes,LM)小鼠巨噬细胞外泌体(Exosomes,Exos)并分析其miRNA表达谱,为揭示巨噬细胞Exos miRNA在LM感染中的调控机制奠定研究基础。[方法]以未感染LM的巨噬细胞为对照组,感染LM的巨噬细胞为试验组,采用超速离心法分离提取巨噬细胞上清中的Exos,通过透射电镜、纳米颗粒追踪技术和Western blot对Exos形态、大小及表面标志分子特征进行鉴定。利用Illumina SE50测序平台对2组巨噬细胞Exos miRNA进行Small RNA-seq测序,筛选出显著差异表达的miRNA。使用Targetscan、miRDB和miRWalk数据库对差异表达miRNA靶基因进行预测,并对差异miRNA靶基因进行GO和KEGG-Pathway功能富集分析。利用Cytoscape软件绘制前20位Hub基因的miRNA-mRNA调控网络图。[结果]Exos直径为30~150 nm,具有典型的双层膜结构,Exos表面标志分子CD9、CD63和TSG101呈阳性表达。高通量测序结果显示,与对照组相比,试验组Exos中共筛选出9个显著差异表达的miRNA,其中显著下调基因8个(mmu-miR-7a-5p、mmu-miR-365-2-5p、mmu-miR-122-5p、mmu-miR-122b-3p、mmu-let-7i-5p、mmu-miR-151-3p、mmu-miR-182-5p和mmu-miR-1198-5p),显著上调基因1个(mmu-miR-192-5p),共预测miRNA调控靶基因1064个。GO富集分析结果显示,差异miRNA靶基因主要富集在轴突形成、细胞连接组装、肌动蛋白结合和金属离子跨膜转运等过程;KEGG分析显示,靶基因显著富集在cGMP-PKG信号通路和FcγR介导的吞噬作用通路。[结论]感染LM的小鼠巨噬细胞Exos miRNA表达谱发生了显著改变,其调控的潜在靶基因主要参与感染和免疫反应等信号通路。

Rhombencephalitis caused by Listeria monocytogenes with hydrocephalus and intracranial hemorrhage:A case report and review of the literature

BACKGROUND Listeria monocytogenes(L. monocytogenes), a Gram-positive facultatively intracellular bacterium, is the causative agent of human listeriosis. Listeria infection is usually found in immunocompromised patients, including elderly people, pregnant women, and newborns, whereas it is rare in healthy people. L.monocytogenes may cause meningitis, meningoencephalitis, and some very rare and severe complications, such as hydrocephalus and intracranial hemorrhage,which cause high mortality and morbidity worldwide. Up to now, reports on hydrocephalus and intracranial hemorrhage due to L. monocytogenes are few.CASE SUMMARY We herein report a case of rhombencephalitis caused by L. monocytogenes in a 29-year-old man. He was admitted to the hospital with a 2-d history of headache and fever. He consumed unpasteurized cooked beef two days before appearance.His medical history included type 2 diabetes mellitus, and contaminated beef intake 2 d before onset. Cerebrospinal fluid analysis revealed Gram-positive rod infection, and blood culture was positive for L. monocytogenes. Magnetic resonance imaging findings suggested rhombencephalitis and hydrocephalus.Treatment was started empirically and then modified according to the blood culture results. Repeated CT images were suggestive of intracranial hemorrhage.Although the patient underwent aggressive external ventricular drainage, he died of a continuing deterioration of intracranial conditions.CONCLUSION Hydrocephalus, intracranial hemorrhage, and inappropriate antimicrobial treatment are the determinations of unfavorable outcomes.

PCR-based methodologies for detection and characterization of Listeria monocytogenes and Listeria ivanovii in foods and environmental sources

Listeria monocytogenes is an important foodborne pathogen responsible for listeriosis,a fatal disease.It is widely distributed in various foods and environmental sources.In this review,we focused on addressing PCR-based technologies,including conventional PCR,qPCR and droplet digital PCR(ddPCR).Specifically,we described(a)conventional PCR and mono-,duplex-and multiplex-qPCR methodologies;(b)development and applications of gene HlyA-,Iap-,PrfA–and SsrA-based conventional and qPCR assays as well as PCR assays targeting newly identified gene targets for specific detection of L.monocytogenes;differentiation of viable from dead L.monocytogenes by qPCR in conjugation with propidium monoazide pretreatment;PCR-based serotype identification of L.monocytogenes isolates;PCR-based detection of L.ivanovii,infecting ruminants,differentiation of L.monocytogenes from other Listeria species;and sigB-gene based PCR identification of Listeria spp;(c)applications of ddPCR in detection of L.monocytogenes;and(d)application of qPCR assays in detection and subtyping of L.monocytogenes in milk and dairy products;meats,meat products and meat-processing environment;and seafood,seafood products and processing environment.Our goal was to provide a relatively comprehensive overview of PCR-based methodologies available in detection,characterization and subtyping of various strains of L.monocytogenes in foods and environmental sources.

单核细胞增生李斯特菌LIPI-4 Lm4b_02327的基因克隆、生物信息学分析及原核表达

目的 试验旨在获得单核细胞增生李斯特菌新疆冷冻鸡肉分离株LM928中LIPI-4 Lm4b_02327基因的重组蛋白。方法 根据Gen Bank中LM Clip80459菌株(登录号CAS06084.1)Lm4b_02327序列设计特异性引物,利用PCR对Lm4b_02327基因进行扩增,纯化目的片段后克隆至pMD19-T载体,双酶切筛选阳性克隆进行测序。测序后利用软件预测Lm4b_02327序列编码蛋白质的理化性质、二级结构和三级结构,对该基因片段的核苷酸序列及编码的氨基酸序列进行同源性对比。同时构建pET32a-Lm4b_02327重组质粒,将其转化至大肠杆菌BL21(DE3)感受态细胞中,诱导表达,经SDS-PAGE检测、纯化蛋白后用Western Blot鉴定。结果 LM928菌株的Lm4b_02327基因全长为315 bp,共编码105个氨基酸,该蛋白为偏酸性、无信号肽、亲水性、无跨膜结构、定位于细胞质的不稳定蛋白,该蛋白质预测为PTSLacEⅡA组分。LM928菌株Lm4b_02327基因的核苷酸和氨基酸序列与CFSAN023463、52854、02-6680、02-6679、ICDC-LM188、LM3、N2306、GTA-L356和Clip80459菌株的同源性均为100.0%,与52860、FSL-J1-158和FSL J1-208菌株的核苷酸同源性分别为99.7%、97.8%和97.8%,与52860、FSL-J1-158和FSL J1-208菌株的氨基酸同源性分别为99.0%、94.3%和94.3%。系统进化树显示,LM928菌株的Lm4b_02327基因与4b血清型菌株聚为同一分支。经诱导后,pET32a-Lm4b_02327重组质粒在大肠杆菌BL21中大量表达,经SDS-PAGE和Western Blot鉴定表明该重组蛋白大小约为30 kDa,与预期大小一致。结论 本研究成功克隆Lm4b_02327基因,并获得该蛋白的大量表达,为深入研究蛋白功能奠定基础。

In vitro Selection of DNA Aptamers and Fluorescence-Based Recognition for Rapid Detection Listeria monocytogenes

Aptamers are specific nucleic acid sequences that can bind to a wide range of nucleic acid and non-nucleic acid targets with high affinity and specificity. Nucleic acid aptamers are selected in vitro from single stranded DNA or RNA ligands containing random sequences of up to a few hundred nucleotides. Systematic evolution of ligands by exponential enrichment （SELEX） was used to select and PCR amplify DNA sequences （aptamers） capable of binding to and detecting Listeria monocytogenes, one of the major food-borne pathogens. A simplified affinity separation approach was employed, in which L. monocytogenes in exponential （log） phase of growth was used as the separation target. A fluorescently-labeled aptamer assay scheme was devised for detecting L. monoeytogenes. This report described a novel approach to the detection of L. monocytogenes using DNA aptamers. Aptamers were developed by nine rounds of SELEX. A high affinity aptamer was successfully selected from the initial random DNA pool, and its secondary structure was also investigated. One of aptamers named e01 with the highest affinity was further tested in aptamer-peroxidase and aptamer-fluorescence staining protocols. This study has proved the principle that the whole-cell SELEX could be a promising technique to design aptamer-based molecular probes for dectection of pathogenic microorganisms without tedious isolation and purification of complex markers or targets.

产单核细胞李氏杆菌Lm4b_02325/26双基因缺失株构建及部分生物学特性试验

旨在构建食源性产单核细胞李氏杆菌毒力岛4(LIPI-4)中的抗转录终止子(Lm4b_02325)和未知蛋白(Lm4b_02326)基因的双缺失株,研究Lm4b_02325/26基因对产单核细胞李氏杆菌(Listeria monocytogenes,LM)的部分生物学特性的影响。利用同源重组技术构建LM928ΔLm4b_02325/26双缺失株,测定LM928和LM928ΔLm4b_02325/26双缺失株在脑心浸出液肉汤(brain heart infusion broth, BHI)、不同EtOH浓度、不同NaCl浓度、不同pH、不同温度下的D_(600 nm),绘制生长曲线;RT-qPCR检测双基因缺失前后体外BHI培养环境下部分毒力因子转录水平;平板计数测定其对鼠巨噬细胞RAW264.7的黏附、侵袭与胞内增殖情况;感染C57BL/6小鼠后检测肝、脾、脑组织中的细菌数量。结果表明,成功构建具有遗传稳定性的双缺失株LM928ΔLm4b_02325/26。在含0.5%~10%NaCl或3%~4.5%EtOH的培养基中,双缺失株与野毒株生长没有明显差异,在pH=5条件下,双缺失株的生长率显著高于野毒株,pH=9条件下双缺失株的生长率显著低于野毒株。在不同温度(4℃、37℃、42℃)BHI培养基中,双缺失株与野毒株生长没有明显差异。Lm4b_02325/26基因双缺失株在BHI培养基中毒力因子hly、inlC和PlcA极显著上调(P<0.01),mpl、inlB、actA、inlP、PlcB、prfA、SigB、iap和inlA极显著下调(P<0.01);双缺失株对RAW264.7细胞的黏附率(14.86%)和侵袭率(2.23%)明显低于野毒株的黏附率(22.93%)和侵袭率(4.28%)(P<0.01);3、6、12 h时胞内增殖数量极显著低于野毒株(P<0.01);双缺失株与野毒株感染小鼠后,载菌量在肝、脾中没有显著差异,在脑组织中双缺失株载菌量为10~4,高于野毒株的10~(3.07),差异极显著(P<0.01)。综上认为,LIPI-4的Lm4b_02325和Lm4b_02326基因参与LM毒力因子的表达和脑组织的定植能力,与弱酸强碱条件下适应力及对RAW264.7细胞的黏附、侵袭和胞内增殖有关。本研究为LIPI-4的功能研究奠定了基础。

Survival of <i>Listeria monocytogenes</i>during Frying of Chicken Burger Patties

This study was aimed to determine sufficient frying time to reduce the number of Listeria monocytogenes present in chicken burger patties to non-detectable level which is fit for human consumption. Commercially available chicken burger patties were artificially contaminated with L. monocytogenes at level of approximately 9 log CFU/ml. The contaminated chicken burger patties were cooked for 0, 2, 4, 5, 8, and 10 minutes to determine survival of L. monocyto-genes. Results demonstrated a linear correlation between mean log reduction of L. monocytogenes and frying time. L. monocytogenes was not detected in chicken burger patties that were cooked for 6 minutes and above. As a result from this study, it is suggested that a minimum frying time for burger patties is 6 minutes. This can be treated as a safety measure to avoid consequences of consumption of undercooked burger patties.

Prevalence and methodologies for detection,characterization and subtyping of Listeria monocytogenes and L.ivanovii in foods and environmental sources

Listeria monocytogenes,one of the most important foodborne pathogens,can cause listeriosis,a lethal disease for humans.L.ivanovii,which is closely related to L.monocytogenes,is also widely distributed in nature and infects mainly warm-blooded ruminants,causing economic loss.Thus,there are high priority needs for methodologies for rapid,specific,cost-effective and accurate detection,characterization and subtyping of L.monocytogenes and L.ivanovii in foods and environmental sources.In this review,we(A)described L.monocytogenes and L.ivanovii,world-wide incidence of listeriosis,and prevalence of various L.monocytogenes strains in food and environmental sources;(B)comprehensively reviewed different types of traditional and newly developed methodologies,including culture-based,antigen/antibody-based,LOOP-mediated isothermal amplification,matrix-assisted laser desorption ionization-time of flight-mass spectrometry,DNA microarray,and genomic sequencing for detection and characterization of L.monocytogenes in foods and environmental sources;(C)comprehensively summarized different subtyping methodologies,including pulsed-field gel electrophoresis,multi-locus sequence typing,ribotyping,and phage-typing,and whole genomic sequencing etc.for subtyping of L.monocytogenes strains from food and environmental sources;and(D)described the applications of these methodologies in detection and subtyping of L.monocytogenes in foods and food processing facilities.

Listeria monocytogenes following orthotopic liver transplantation:Central nervous system involvement and review of the literature

Listeria monocytogene is a well-recognized cause of bacteremia in immunocompromised individuals, including solid organ transplant recipients, but has been rarely reported following orthotopic liver transplantation. We describe a case of listeria meningitis that occurred within a week after liver transplantation. The patient developed a severe headache that mimicked tacrolimus encephalopathy, and was subsequently diagnosed with listeria meningitis by cerebrospinal fluid culture. The infection was successfully treated with three-week course of intravenous arnpicillin. Recurrent hepatitis C followed and was successfully treated with interferon alfa and ribavirin. Fourteen cases of listeriosis after orthotopic liver transplantation have been reported in the English literature. Most reported cases were successfully treated with intravenous ampicillin. There were four cases of listeria meningitis, and the mortality of them was 50%. Early detection and treatment of listeria meningitis are the key to obtaining a better prognosis.

Inhibitory Effect of Live-Attenuated Listeria Monocytogenes-based Vaccines Expressing MIA Gene on Malignant Melanoma

Listeria monocytogenes(LM),a Gram-positive facultative intracellular bacterium,can be used as an effective exogenous antigen expression vector in tumor-target therapy.But for successful clinical application,it is necessary to construct attenuated LM stain that is safe yet retains the potency of LM based on the full virulent pathogen.In this study,attenuated LM and recombinants of LM expressing melanoma inhibitory activity(MIA) were constructed successfully.The median lethal dose(LD 50) and invasion efficiency of attenuated LM strains were detected.The recombinants were utilized for immunotherapy of animal model of B16F10 melanoma.The level of MIA mRNA expression in tumor tissue was detected by using real-time polymerase chain reaction(PCR) with specific sequence,meanwhile the anti-tumor immune response was assayed by flow cytometric analysis and enzyme-linked immunosorbent spot(ELISPOT) assay.The results showed the toxicity and invasiveness of attenuated LM were decreased as compared with LM,and attenuated LM expressing MIA,especially the double-genes attenuated LM recombinant,could significantly induce anti-tumor immune response and inhibit tumor growth.This study implicates attenuated LM may be a safer and more effective vector for immunotherapy of melanoma.

Application Progress of Recombinant Attenuated Listeria monocytogenes in Tumor Immunotherapy

Much progress of application of bacterial vaccine in treatment and prevention of tumor was acquired,which showed broad prospect in clinical study of animals and humans. Listeria monocytogenes( L. monocytogenes) was considered much important by virtue of its special characteristic of biology and immunology.L. monocytogenes was ingested by professional or part-time phagocytes,survived and proliferated in the phagocytes under synergism of toxic factor secreted by itself,meanwhile,the cellular and humoral immune response was induced. Antigenic gene of specific tumor was loaded in the attenuated L. monocytogenes,which can enhance immune response of host cells. Effective cell targeted to enter tumor tissue and acted on tumor cells to induce apoptosis of tumor cells. Tumor degenerated not easy to reappear. Therefore,recombinant attenuated L. monocytogenes was a safe and effective anti-cancer vaccine vector. Now the work of researchers mainly focuses on solving practical problem in clinical application. Biological characteristics of L. monocytogenes,feasibility and superiority of L. monocytogenes as targeted vaccine vector,problem and prospect of L. monocytogenes in clinical application of anti-tumor were reviewed in this paper.

Use of Bacteriocin Producing <i>Lactococcus lactis</i>subsp. <i>lactis</i>LABW4 to Prevent <i>Listeria monocytogenes</i>Induced Spoilage of Meat

A bacteriocin producing strain of Lactococcus lactis subsp. lactis LABW4 was isolated from naturally fermented milk product which exhibited strong antibacterial activity against Listeria monocytogenes MTCC657, a food spoilage psychrophilic organism. Both cell free and heat killed supernatants of LABW4 were effective to produce zones of inhibition against L. monocytogenes in vitro. The antibacterial metabolite(s) of LABW4 showed strong cidal effect on the growth of L. monocytogenes. Meat samples, mixed with heat killed supernatant of LABW4 when inoculated with Listeria, remain fresh up to 25 days in refrigerated condition whereas spoilage started immediately after 24 hours of inoculation for control sets. Enhancement of Lactate dehydrogenase of L. monocytogenes upon treatment with LABW4 cell free supernatant suggested its lytic mode of action. Cell lysis or degradations were also supported by scanning electron micrograph of treated cells.

Detection of Listeria monocytogenes in Dairy Food by Loop-mediated Isothermal Amplification(LAMP)

[Objective] This study aimed to detect the reliability of LAMP method for detecting Listeria monocytogenes in dairy food. [Method] Based on the sequence of hlyA gene encoding listeriolysin O in Listeria monocytogenes, the LAMP method was established for detecting Listeria monocytogenes in dairy food. [Result] The es- tablished LAMP rapid detection method has .high specificity and sensitivity, which are equivalent to those of real-time fluorescent quantitative PCR. The detection re- sults of Listeria monocytogenes in dairy food by established LAMP method were completely consistent with those by bacterial isolation method. [Conclusion] The de- tection results of Listeria monocytogenes by LAMP method can be directly identified by naked eye, so the established LAMP method was suitable for the detection of Listeria monocytogenes in dairy food in emergency situations.

Antimicrobial Resistance,Virulence Profile,and Molecular Characterization of Listeria monocytogenes Isolated from Ready-to-eat Food in China,2013-2014

We aimed to investigate the potential pathogenic profile and antibiotic resistance of Listeria monocytogenes isolated from ready-to-eat food in China.Antimicrobial resistance was determined by broth microdilution following the Clinical and Laboratory Standards Institute protocol Molecular serotyping,virulence,and resistance genes were identified using PCR.Multi-locus