Thesis (Ph.D.)--University of Wyoming, 2007. / Title from PDF title page (viewed on June 17, 2009). Includes bibliographical references (p. 83-103).

Listeria monocytogenes was the causative agent of the nationwide 2008 outbreak associated with contaminated ready-to-eat meat products. Within the whole genome DNA sequences of the outbreak isolates we previously identified a novel 50kb genomic island, designated as Listeria Genomic Island 1 (LGI1). LGI1 is predicted to contribute to Listeria pathogenesis and/or environmental persistence because it encodes genes related to known virulence factors and mobilization functions, including a putative type IV secretion system and a putative small multidrug resistance efflux pump. The distribution of LGI1 in Canadian L. monocytogenes isolates was determined by PCR screening for LGI1 within 126 isolates from 1987 to 2010 that represented different serotypes and pulsed-field gel electrophoresis (PFGE) patterns. To assess the evolutionary history and genetic diversity of this island, total LGI1 sequences from 15 whole-genome sequences were compared, and from the full study panel of isolates,PCR screening for the chromosomal insertion site and multiple LGI coding sequences were performed. LGI1 was detected almost exclusively in serotype 1/2a isolates, and within those, the isolates predominantly had the same PFGE patterns. These LGI1-encoding isolates also exclusively belonged to the multi-locus sequence typing (MLST)clonal complex 8. LGI1 was highly genetically conserved and it was inserted at the same location within the genome in 65 of the 67 isolates that harboured the island. To study the function and expression of LGI1, antimicrobial susceptibility assays,bioinformatic analyses and real-time reverse-transcription PCR were used. Isolates encoding LGI1 had an increased tolerance to quaternary ammonium compounds commonly used in sanitizing agents (benzalkonium chloride (BCl) and benzethonium chloride (BeCl)) compared to isolates lacking LGI1 (but still highly related by MLST and PFGE). LGI1 is also tightly regulated, with expression of 13 of 16 tested coding sequences only being induced by the presence of sub-inhibitory concentrations of BCl,and one predicted regulator being expressed under all conditions. This study indicates that the vast majority LGI encoding CC8 isolates share a common progenitor L. monocytogenes ancestor that acquired LGI1 in a single evolutionary event. LGI1 has remained genetically conserved since that time, and the functions contributed by this island minimally include an increased tolerance to sanitizer agents.

SANTRAUKA Eglė Kašėtaitė LISTERIA MONOCYTOGENES BAKTERIJŲ APTIKIMAS MAISTO ŽALIAVOSE IR PRODUKTUOSE BEI RIZIKOS ŽMONĖMS ĮVERTINIMAS Baigiamasis magistro darbas Darbo vadovė: dr. Silvija Kiverytė Vilniaus Universitetas Medicinos fakultetas Fiziologijos, biochemijos ir laboratorinės medicinos katedra Darbo apimtis 57 lapai, 4 lentelės ir 24 paveikslai Listeria monocytogenes bakterijos yra vienos iš pavojingiausių maiste aptinkamų patogenų. Patekusios į maisto žaliavas ir produktus jos gali sukelti rimtus žmonių apsinuodijimus ir pridaryti didelius ekonominius nuostolius. Šiuo metu pasaulyje, taip pat ir Lietuvoje daug dėmesio skiriama per maistą plintančių patogeninių mikroorganizmų sukeltų užkrečiamųjų ligų protrūkiams tirti. Vienas iš Listeria monocytogenes nustatymo maiste būdų yra mikrobiologinis kokybinis aptikimo metodas. Kuris plačiai taikomas pasaulyje, nes yra nebrangus, efektyvus ir nedaro poveikio aplinkai. Listerioze – gyvūnų ir žmonių užkrečiama liga, kurią sukelia gramteigiamos Listeria monocytogenes lazdelės. Užsikrėtimui šia liga įtakos turi žmonių amžius, nusilpusi imuninė sistema, nėščiųjų imlumas bakterijoms, netinkamas maisto paruošimas bei vartojimas ir kita. Šio baigiamojo darbo tikslas yra įvertinti listerijų (Listeria monocytogenes) paplitimą maisto žaliavose ir produktuose 2001-2008 metais. Maisto žaliavų ir produktų mėginiai buvo imami bei tyrimai atliekami Nacionalinėje visuomenės sveikatos priežiūros laboratorijoje (NVSPL) Klaipėdos skyriuje... [toliau žr. visą tekstą] / SUMMARY Eglė Kašėtaitė LISTERIA MONOCYTOGENES BACTERIA DETECTION IN FOOD RAW MATERIALS AND PRODUCTS AND RISK FOR HUMANS ASSESSMENT Graduation Dissertation for Master’s Degree The Supervisor of the Work: dr. Silvija Kiverytė Vilnius University Faculty of Medicine Department of Physiology, Biochemistry and Laboratory Medicine Scope of the Work: 57 pages, 4 tables and 24 figures Listeria monocytogenes bacteria are one of the most dangerous pathogens found in the food. Introduced into the raw food materials and products they can cause serious people poisoning and make some substantial economic losses. Currently the world, as well and Lithuania are focused on investigation outbreaks of food-borne pathogen causes on infectious diseases. One of Listeria monocytogenes detection methods in the microbiological food is qualitative detection method. It is widely used in the world, because it is inexpensive, effective and does not affect the environment. Listeriosis - animal and human infectious disease caused by L. monocytogenes Gram-rods. Infected with this disease have an impact of people's age, weakened immune systems, pregnant susceptibility to bacteria, improper food preparation and consumption, or others. The Graduation Dissertation for Master’s Degree is to assess the listeria (Listeria monocytogenes) the prevalence of food materials and products in the year of 2001-2008. The raw food materials and product samples were taken and tested on the National Public Health Laboratory... [to full text]

Listeria monocytogenes was the causative agent of the nationwide 2008 outbreak associated with contaminated ready-to-eat meat products. Within the whole genome DNA sequences of the outbreak isolates we previously identified a novel 50kb genomic island, designated as Listeria Genomic Island 1 (LGI1). LGI1 is predicted to contribute to Listeria pathogenesis and/or environmental persistence because it encodes genes related to known virulence factors and mobilization functions, including a putative type IV secretion system and a putative small multidrug resistance efflux pump. The distribution of LGI1 in Canadian L. monocytogenes isolates was determined by PCR screening for LGI1 within 126 isolates from 1987 to 2010 that represented different serotypes and pulsed-field gel electrophoresis (PFGE) patterns. To assess the evolutionary history and genetic diversity of this island, total LGI1 sequences from 15 whole-genome sequences were compared, and from the full study panel of isolates,PCR screening for the chromosomal insertion site and multiple LGI coding sequences were performed. LGI1 was detected almost exclusively in serotype 1/2a isolates, and within those, the isolates predominantly had the same PFGE patterns. These LGI1-encoding isolates also exclusively belonged to the multi-locus sequence typing (MLST)clonal complex 8. LGI1 was highly genetically conserved and it was inserted at the same location within the genome in 65 of the 67 isolates that harboured the island. To study the function and expression of LGI1, antimicrobial susceptibility assays,bioinformatic analyses and real-time reverse-transcription PCR were used. Isolates encoding LGI1 had an increased tolerance to quaternary ammonium compounds commonly used in sanitizing agents (benzalkonium chloride (BCl) and benzethonium chloride (BeCl)) compared to isolates lacking LGI1 (but still highly related by MLST and PFGE). LGI1 is also tightly regulated, with expression of 13 of 16 tested coding sequences only being induced by the presence of sub-inhibitory concentrations of BCl,and one predicted regulator being expressed under all conditions. This study indicates that the vast majority LGI encoding CC8 isolates share a common progenitor L. monocytogenes ancestor that acquired LGI1 in a single evolutionary event. LGI1 has remained genetically conserved since that time, and the functions contributed by this island minimally include an increased tolerance to sanitizer agents.

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Thesis (Ph. D.)--University of Hawaii at Manoa, 2001. / Includes bibliographical references (leaves 186-201). Also available on microfiche.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 91-97). Also available via the Internet.

München, Techn. Univ., Diss., 2001. / Computerdatei im Fernzugriff.

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