Browsing by Author "Tikkanen, Jouni"

The Master's thesis was completed as part of the joint project (Haittaeläin) by the Finnish Food Authority (Ruokavirasto) and Natural Resources Institute Finland (Luke). In the project, rodents and shrews caught on farm premises were investigated for zoonotic bacterial pathogens. This thesis covers the thermophilic cam-pylobacter findings in the caught pests in autumn 2017.Rodents and shrews caught on farm premises were investigated for zoonotic bacterial pathogens. This thesis deals with the result of thermophilic campylobac-ters isolated from the pests in the autumn 2017. Thermophilic campylobacters (Campylobacter jejuni ja Cam-pylobacter coli) cause gastroenteritis called campylobacteriosis in humans, which is one of the most common cause for human gastroenteritis in the world. The literature review discusses the characteristics of thermo-philic campylobacters and their epidemiology, which focused on aspects of a public health and risk factors for campylobacteriosis and the major sources of campylobacters. Moreover, a current knowledge of campylo-bacters’ occurrence in rodents and shrews were summarized in the literature review. The presence of thermophilic campylobacters was investigated from 227 pooled samples, which comprised of a total of 442 intestinal samples collected from 12 different species. Three species (yellow-necked mouse, house mouse and bank vole) covered 81,3 % of all caught pests. The numbers of caught pests were not signif-icantly different between the farms when compared to a geographical position (south or north) or a type of farm (pig or cattle). The numbers of captured yellow-necked mice were significantly higher in farms in the south. Especially, yellow-necked mice and bank voles were detected to be campylobacter positive. Other campylobacter positive species were harvest mice, rats, field voles and southern voles. A total of 93 samples were detected as campylobacter positive and all of them were identified as C. jejuni. There was not signifi-cant difference on the numbers of campylobacter positive samples between the farms when compared the geographical position or the type of farm. 46 isolates of all 96 campylobacter positive samples were selected for a whole genome sequencing. After the raw read data was assembled, the contigs were analysed with MLST and cgMLST typing schemes by Ridom SeqSphere+. 41 isolates contained 14 new sequence types (STs). Instead, 5 isolates contained previously described STs: ST-1304, ST-2219 and ST-4791. According to MLST typing isolates obtained from voles differed from isolates from mice and rats. Moreover, cgMLST typing supported the conclusion. In the cgMLST typing scheme vole’s isolates were found to have more missing loci than isolates from mice or rats. Therefore, all isolates from voles, apart from two bank vole isolates belonging to ST-1304, contained less than 90 % loci compared to a reference genome. Furthermore, these same isolates were poorly identified in MALDI TOF analysis unlike other isolates. One interpretation to the difference between isolates could be that isolates from voles belong to a new C. jejuni subspecies.