Prevalence and counts of Listeria monocytogenes and Campylobacter spp. in food and molecular characterisation of the isolates in Estonia
| dc.contributor.advisor | Roasto, Mati | |
| dc.contributor.author | Mäesaar, Mihkel | |
| dc.contributor.department | Institute of Veterinary Medicine and Animal Sciences | eng |
| dc.contributor.other | Møller Nielsen, Eva (opponent) | |
| dc.date.accessioned | 2023-11-06T12:46:29Z | |
| dc.date.available | 2023-11-06T12:46:29Z | |
| dc.date.defensed | 2022-12-14 | |
| dc.date.issued | 2022 | |
| dc.description | A Thesis for applying for the degree of Doctor of Philosophy in Food Science. | eng |
| dc.description | Väitekiri filosoofiadoktori kraadi taotlemiseks toiduteaduse erialal. | est |
| dc.description.abstract | Listeria monocytogenes is a bacterial zoonotic agent and a major cause of listeriosis in humans. The invasive form of listeriosis causes severe illness and can be fatal. In the European Union (EU), 2,621 cases of listeriosis were reported in humans in 2019, with a 17.6% case fatality rate. A study carried out in 2012–2013 found that 16.8% of the 185 samples of ready-to-eat fish (RTE) products tested positive, but only one salted and sliced salmon fillet product exceeded the European Union food safety criterion of 100 CFU/g at the end of its shelf-life. Unlike L. monocytogenes, infections caused by Campylobacter jejuni are significantly more common in humans. Campylobacteriosis usually affects people with mild symptoms and is typically a self-limiting disease. In 2019, 220,682 cases of campylobacteriosis were registered in the EU, but the mortality rate per case was only 0.03% compared to listeriosis. A survey conducted in 2012 found that 35.0% of the 220 samples of fresh broiler chicken meat from Estonia, Latvia and Lithuania sold in Estonia were contaminated with campylobacters. Higher prevalence, counts and antibiotic resistance of campylobacters were associated with imported chicken broiler products. These indicators were low in fresh broiler chicken meat products of Estonian origin. The molecular methods used in the study allowed the strain of L. monocytogenes isolated from Estonian food to be associated with a multi-country outbreak of listeriosis in several European countries in 2014–2019. A retrospective survey also revealed that the same strain was already in the company's RTE fish products before the outbreak was first registered. Molecular studies also showed that the primary source of human cases of campylobacteriosis in Estonia is mainly related to poultry, including poultry meat. Systematic application of whole-genome sequencing in routine surveillance will contribute to the effectiveness of investigating food-borne outbreaks and thus to the prevention of related cases. | eng |
| dc.description.abstract | Listeria monocytogenes on bakteriaalne zoonootiline haigustekitaja ja peamine listerioosi põhjustaja inimestel. Invasiivne listerioos põhjustab rasket haigestumist ja võib lõppeda inimese surmaga. Euroopa Liidus registreeriti 2019. aastal 2 621 listerioosi haigestumist 17,6% juhtumipõhise suremusega. Aastatel 2012–2013 läbiviidud uuringutes tuvastati, et 185-st söömisvalmis kalatootest oli positiivsed 16,8%, kuid ainult ühes viilutatud soolalõhefilee söömisvalmis tootes ületas L. monocytogenes’e arvukus säilimisaja lõpus Euroopa Liidus kehtestatud toiduohutuse kriteeriumi 100 CFU/g. Erinevalt L. monocytogenes’est põhjustab Campylobacter jejuni märksa sagedamini inimeste haigestumist. Üldjuhul tekitab kampülobakterioos inimestel kergeid sümptomeid ja on tavaliselt iseparanev haigus. Euroopa Liidus registreeriti 2019. aastal 220 682 kampülobakterioosi haigestumist, kuid juhtumipõhine suremus oli võrreldes listerioosiga vaid 0,03%. 2012. aastal korraldatud uuringus tuvastati, et 220-st Eestis müüdavast Eesti, Läti ja Leedu päritolu värskest kanabroileritootest oli kampülobakteritega saastunud 35,0%. Kampülobakterite suuremat levimust, kõrgemat arvukust ning antibiootikumiresistentsust seostati imporditud kanabroileritoodetega. Eesti kanabroilerilihatoodetes olid nimetatud näitajad madalamad. Uurimuses kasutatud molekulaarsed meetodid võimaldasid Eesti toidust eraldatud L. monocytogenes’e tüve seostada mitut Euroopa Liidu riiki hõlmanud listerioosi haiguspuhanguga. Samuti selgus tagasivaateuuringust, et sama tüvi oli ettevõtte toodangus juba enne registreeritud puhangu algust. Molekulaarsete uuringutega tõestati, et Eestis ja teistes Baltiriikides on inimeste kampülobakterioosi algallikaks peamiselt kodulinnud, sealhulgas kodulinnuliha. Täisgenoomse sekveneerimise süstemaatiline rakendamine rutiinses järelevalves aitab kaasa toidutekkeliste haiguspuhangute uurimise tõhususele ja seeläbi ka haigusjuhtumite ennetamisele. | est |
| dc.description.sponsorship | The publication of this dissertation is supported by the Estonian University of Life Sciences. | eng |
| dc.identifier.isbn | 978-9916-669-70-9 | |
| dc.identifier.issn | 2382-7076 | |
| dc.identifier.uri | http://hdl.handle.net/10492/8664 | |
| dc.identifier.uri | https://doi.org/10.15159/emu.109 | |
| dc.publisher | Estonian University of Life Sciences | eng |
| dc.relation | This work was supported by the Estonian Research Council grant (PRG1441). | eng |
| dc.relation.ispartofseries | Doctoral Theses of the Estonian University of Life Sciences | eng |
| dc.relation.ispartofseries | Eesti Maaülikooli doktoritööd | est |
| dc.rights | © Mihkel Mäesaar, 2022 | |
| dc.rights | info:eu-repo/semantics/openAccess | eng |
| dc.rights.uri | https://www.riigiteataja.ee/en/eli/ee/Riigikogu/act/519062017005/consolide | est |
| dc.subject | dissertations | eng |
| dc.subject | Listeria monocytogenes | lat |
| dc.subject | Campylobacter spp. | lat |
| dc.subject | listeriosis | eng |
| dc.subject | Campylobacter infections | eng |
| dc.subject | prevalence (statistics) | eng |
| dc.subject | abundance | eng |
| dc.subject | food contamination | eng |
| dc.subject | food safety | eng |
| dc.subject | fowl | eng |
| dc.subject | fish products | eng |
| dc.title | Prevalence and counts of Listeria monocytogenes and Campylobacter spp. in food and molecular characterisation of the isolates in Estonia | eng |
| dc.title.alternative | Listeria monocytogenes’e ja Campylobacter spp. levimus ja arvukus toidus ning tüvede molekulaarne iseloomustus Eestis | est |
| dc.type | info:eu-repo/semantics/doctoralThesis | eng |
| dc.type.qualificationname | PhD |
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