Editorial
Makaleler > Editöre Mektup · 2003
Yazarlar: Emel Tumbay
FEMS Immunology & Medical Microbiology, Uluslararası, Wos, 2003, cilt 35, ss 171-171
DOI: 10.1016/s0928-8244(03)00034-8
Özet
The bacterium Listeria has become a significant subject in biomedical research due to its central position in medical microbiology, food microbiology, cell biology and immunology. The detection and identification of Listeria monocytogenes is not easy. New isolation and enrichment media have been developed for better and more rapid results, enabling the recovery of the bacterium from various food products with ease. More comparative studies are needed to achieve one final method. Although Listeria is in general susceptible to a wide range of antimicrobials, most antibiotics are not bactericidal for this intracellular bacterium. At present clinical experience shows that the combination of amoxicillin and gentamicin is the best choice for treatment. Listeriosis is mainly an infection of selected groups such as neonates, pregnants, elderly, transplant recipients and other patients with impaired cell-mediated immunity. Central nervous system infections, endocarditis, gastroenteritis and localized infections are frequent forms of the disease. The current murine models of pregnancy-associated listeriosis have proven insufficient maternal immune response to L. monocytogenes during pregnancy. Since listeriosis is a food-borne infection, food safety is of utmost importance in the prevention and control of the disease. To lower the risk associated with food-borne diseases, such as listeriosis, FAO and WHO have recently started risk assessment studies. ‘The FAO/WHO Listeria risk assessment was undertaken in part to determine how previously developed risk assessments at the national level could be adapted or expanded to address concerns related to L. monocytogenes in ready-to-eat foods at an international level’. A limited number of biochemical markers, such as hemolytic activity, Christie–Atkins–Munch–Petersen (CAMP) test and chromogenic reactions are used in the identification of Listeria species. For the final identification of atypical strains of L. monocytogenes molecular techniques are recommended. Serotyping serves for the confirmation of Listeria at the genus level. By pulsed-field gel electrophoresis, it is now possible to characterize L. monocytogenes strains, and that can serve as an epidemiological tool determining the genetic characteristics of the strains. Polymerase chain reaction is useful in the identification, particularly in clinical cases with a history of prior antibiotic use. Studies on host–pathogen interactions in a murine model have revealed that tissue reaction and accompanying eradication of listeriae are mainly due to activation of CD4+ T cells, that protective immunity cannot be induced by heat-killed bacteria, and that the amount of induced T cell response correlates with the duration and intensity of a vaccine-induced cytokine response. Related test systems for the T cell immunome analysis of L. monocytogenes were found promising for the rapid identification and characterization of pathogen-specific T cell populations in listeriosis. Studies on Listeria bacteriophages continue. The genomes of some specific phages are sequenced and compared by bioinformatic analysis and physico-molecular techniques. The recombinant endolysins have been found to cause rapid and highly specific lysis of Listeria cells, being applied in molecular biology and biotechnology. New insights have been gained from genome analysis of Listeria within the framework of a European project. Complete genome sequences, DNA/DNA hybridization on focused macroarrays and transcriptome analysis have revealed diversity of the genomes and the expression profiles of different strains of L. monocytogenes. Recent studies on gene expression have added some novel genes to the approximately 20 known virulence genes of L. monocytogenes, required for growth and survival of the bacterium in the intracellular environment. In addition, by nucleic acid-based studies, rapid in situ detection and identification of Listeria are now possible — both in clinical samples as well as in contaminated food. This thematic issue of FEMS Microbiology Immunology and Medical Microbiology entitled ‘The versatility of Listeria species’ contains 15 articles devoted to studies on biology, and environmental and infectious consequences of listeriae and listeriosis. Most contributions stem from the FEMS-Symposium on The Versatility of Listeria Species, which was held in Izmir, Turkey, on dates October 10–11, 2002. Articles by Annette Kolb-Mäurer and coworkers and by Nathalie Garrec with coworkers, who have not participated at the symposium, are also included in this thematic issue to broaden the information on Listeria species. Many thanks to all contributors!