Microglial activation and expression of immune‐related genes in a rat ex vivo nervous system model after infection with Listeria monocytogenes

A wide variety of microorganisms has previously been identified as causes of brain infection. Among them, Listeria monocytogenes has a particular tropism for the central nervous system. To gain knowledge about the immune response elicited by L. monocytogenes in the brain, we used a rat ex vivo organotypic nervous system culture as a model for Listeria infection. Scanning electron microscopy (SEM) revealed that activated microglial cells showing a typical amoeboid morphology are quickly recruited to the surface of the explants after the infection. After bacterial engulfment, these cells appear to act as Trojan horses, releasing the engulfed bacteria inside the brain tissue. We describe cycles of microglial phagocytosis, necrotic cell death and the subsequent removal of cell debris for the first time. Furthermore, we used this ex vivo model to assess the expression profiles of immune relevant genes up to 24 h postinfection by means of q‐PCR‐arrays, finding that a number of inflammation‐promoting genes are upregulated. Shortly after infection by L. monocytogenes, upregulated genes were those that encoded molecules involved in Th1 responses, being the Ccl2 chemokine and members of the interleukin1‐β family the most abundant immunomodulatory signals expressed. After 5 h of infection, L. monocytogenes caused a substantial increase in the expression of TLR1 and TLR2 genes, as well as in several downstream genes of the TLR signaling pathways. © 2013 Wiley Periodicals, Inc.     

多重环介导等温扩增快速检测沙门菌、副溶血弧菌和单核细胞增生性李斯特菌方法的建立

目的：建立能够同时检测沙门菌、副溶血弧菌（VPH）和单核细胞增生性李斯特菌（LM）的多重环介导等温扩增（mLAMP）方法。方法分别针对沙门菌 bcfD 基因、VPH 的 tlh 基因和 LM的 iap 基因设计 mLAMP 引物,以LAMP 进行单重 LAMP 检测。实时浊度监测扩增结果,优化引物浓度配比,进而建立此3种食源性致病菌的mLAMP 检测体系,以 PCR 检测灵敏性作为比较,进行特异性和灵敏性分析。结果实时浊度监测表明,该 mLAMP体系具有良好特异性,可在45 min 内一次性检测以上3种致病菌,且无非特异扩增产生。这3种菌的检测最低限分别为300 fg／μl、4．2 pg／μl 和4．5 pg／μl,与 PCR 检测灵敏度相当。结论该多重 LAMP 可同时检测食品中的沙门菌、VPH 和 LM,可作为大规模样品的初筛或传统方法的辅助方法,用于快速判定样品中是否含有这3种致病菌。     

A case of listerial meningitis treated with a regimen containing panipenem-betamipron

Although panipenem-betamipron, which is commercially available only in Japan, is recommended for treatment of pediatric bacterial meningitis by some experts, only a limited number of clinical studies have been reported. In the present report, we describe a 2-year-old boy with meningitis caused by Listeria monocytogenes who was treated with a regimen containing panipenem-betamipron and recovered without any apparent neurological sequelae. On the basis of our experience and previous reports, panipenem-betamipron appears to be effective for the treatment of listerial meningitis.     

Characterization of a Novel Group of Listeria Phages That Target Serotype 4b Listeria monocytogenes

Listeria monocytogenes serotype 4b strains are the most prevalent clinical isolates and are widely found in food processing environments. Bacteriophages are natural viral predators of bacteria and are a promising biocontrol agent for L. monocytogenes. The aims of this study were to characterize phages that specifically infect serotype 4b strains and to assess their ability to inhibit the growth of serotype 4b strains. Out of 120 wild Listeria phages, nine phages were selected based on their strong lytic activity against the model serotype 4b strain F2365. These nine phages can be divided into two groups based on their morphological characteristics and host range. Comparison to previously characterized phage genomes revealed one of these groups qualifies to be defined as a novel species. Phages LP-020, LP-027, and LP-094 were selected as representatives of these two groups of phages for further characterization through one-step growth curve and inhibition of serotype 4b L. monocytogenes experiments. Listeria phages that target serotype 4b showed an inhibitory effect on the growth of F2365 and other serotype 4 strains and may be useful for biocontrol of L.monocytogenes in food processing environments.     

单核细胞增生李斯特菌的耐药特征及机制

食源性疾病已成为当今世界重大的公共卫生问题,由单核细胞增生李斯特菌(Listeria monocytogenes, Lm)等病原细菌引起的食源性疾病是影响食品安全的主要因素之一。近年来Lm耐药率呈上升趋势,多重耐药菌株不断出现,给世界公共卫生和人类健康带来了严重威胁。Lm的耐药机制十分复杂,包括可移动元件介导的耐药基因转移、药物作用靶点的改变、抗生素的外排作用、灭活酶的产生、生物被膜的形成等多种机制。本文就近年来国内外食品及临床来源Lm的耐药特征及机制进行综述,为李斯特菌病的合理用药,耐药菌株的监测以及公共卫生策略的制定提供科学依据。     

Drastic Therapy for Listerial Brain Abscess Involving Combined Hyperbaric Oxygen Therapy and Antimicrobial Agents

Background

Listeria monocytogenes (L. monocytogenes) is a rare causative pathogen of brain abscess that is often found in immunocompromised patients. Although patients with supratentorial listerial abscesses showed a longer survival with surgical drainage, the standard therapy for patients with subtentorial lesions has not been established.

Case Report

We report herein a patient with supra- and subtentorial brain abscesses caused by L. monocytogenes infection. These abscesses did not respond to antibiotics, and his symptoms gradually worsened. Drainage was not indicated for subtentorial lesions, and the patient was additionally treated with hyperbaric oxygen therapy, which dramatically reduced the volume of abscesses and improved the symptoms.

Conclusions

This is the first report of drastic therapy for a patient with listerial brain abscesses involving combined antibiotics and hyperbaric oxygen therapy. The findings suggest that hyperbaric oxygen therapy is a good option for treating patients with deep-seated listerial abscesses and for who surgical drainage is not indicated.     

Prevalence,identification by a DNA microarray-based assay of human and food isolates Listeria spp. from Tunisia

Objectives

We aimed at evaluating the prevalence of Listeria species isolated from food samples and characterizing food and human cases isolates.

Material and methods

Between 2005 and 2007, one hundred food samples collected in the markets of Tunis were analysed in our study. Five strains of Listeria monocytogenes responsible for human listeriosis isolated in hospital of Tunis were included. Multiplex PCR serogrouping and pulsed field gel electrophoresis (PFGE) applying the enzyme AscI and ApaI were used for the characterization of isolates of L. monocytogenes. We have developed a rapid microarray-based assay to a reliable discrimination of species within the Listeria genus.

Results

The prevalence of Listeria spp. in food samples was estimated at 14% by using classical biochemical identification. Two samples were assigned to L. monocytogenes and 12 to L. innocua. DNA microarray allowed unambiguous identification of Listeria species. Our results obtained by microarray-based assay were in accordance with the biochemical identification. The two food L. monocytogenes isolates were assigned to the PCR serogroup IIa (serovar 1/2a). Whereas human L. monocytogenes isolates were of PCR serogroup IVb, (serovars 4b). These isolates present a high similarity in PFGE. Food L. monocytogenes isolates were classified into two different pulsotypes. These pulsotypes were different from that of the five strains responsible for the human cases.

Conclusion

We confirmed the presence of Listeria spp. in variety of food samples in Tunis. Increased food and clinical surveillance must be taken into consideration in Tunisia to identify putative infections sources.     

2016-2018年湖南省含乳冷冻饮品生产加工过程肠杆菌科和单核细胞增生李斯特菌监测

目的 了解含乳冷冻饮品生产加工过程中肠杆菌科和单核细胞增生李斯特菌(简称单增李斯特菌)的分布,分析其污染的来源. 方法 对湖南省4家含乳冷冻饮品生产企业生产加工过程各个环节的样品进行监测,采用国家标准检测方法对肠杆菌科和单增李斯特菌进行检验,利用脉冲场凝胶电泳(pulse field gel electrophores...