title: Multilocus sequence typing (MLST) and whole-genome MLST of Campylobacter jejuni isolates from human infections in three districts during a seasonal peak in Finland.
abstract: A total of 95 human Campylobacter jejuni isolates acquired from domestic infections and collected from three districts in Finland during the seasonal peak (June to September) in 2012 were analyzed by PCR-based multilocus sequence typing (MLST) and by whole-genome sequencing (WGS). Four predominant sequence types (STs) were detected among the isolates: ST-45 (21%) and ST-230 (14%, ST-45 clonal complex [CC]), ST-267 (21%, ST-283 CC), and ST-677 (19%, ST-677 CC). In districts 1 and 3, most of the infections occurred from early July to the middle of August, with a peak at weeks 29 to 31, but in district 2, the infections were dispersed more evenly throughout 3 months (June to August). WGS data were used for further whole-genome MLST (wgMLST) analyses of the isolates representing the four common STs. Shared loci of the isolates within each ST were analyzed as distance matrices of allelic profiles by the neighbor-net algorithm. The highest allelic variations (>400 different alleles) were detected between different clusters of ST-45 isolates (1,121 shared loci), while ST-230 (1,264 shared loci), ST-677 (1,169 shared loci), and ST-267 isolates (1,217 shared loci) were less diverse with the clusters differing by <40 alleles. Closely related isolates showing no allelic variation (subclusters) were detected among all four major STs. In some cases, they originated from different districts, suggesting that isolates can be epidemiologically connected and may have the same infection source despite being originally identified as sporadic infections.
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Kovanen
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland.
authors.forename: Rauni I
authors.initials: RI
authors.lastname: Kivistö
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland.
authors.forename: Mirko
authors.initials: M
authors.lastname: Rossi
authors.affiliation: Biology Oceanography, Leibniz Institute for Baltic Sea Research, Rostock-Warnemünde, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schott
authors.affiliation: Eastern Finland Laboratory Centre Joint Authority Enterprise (ISLAB), Kuopio District Laboratory, Kuopio, Finland.
authors.forename: Ulla-Maija
authors.initials: UM
authors.lastname: Kärkkäinen
authors.affiliation: Eastern Finland Laboratory Centre Joint Authority Enterprise (ISLAB), Mikkeli District Laboratory, Mikkeli, Finland University of Helsinki, Department of Bacteriology and Immunology, Helsinki, Finland.
authors.forename: Tamara
authors.initials: T
authors.lastname: Tuuminen
authors.affiliation: Keslab Laboratory, Department of Clinical Microbiology, Central Finland Health Care District, Jyväskylä, Finland Fimlab Laboratories, Ltd., Jyväskylä, Finland.
authors.forename: Jaakko
authors.initials: J
authors.lastname: Uksila
authors.affiliation: Department of Medical Sciences, Clinical Microbiology, Uppsala University, Uppsala, Sweden Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Helsinki, Finland.
authors.forename: Hilpi
authors.initials: H
authors.lastname: Rautelin
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland marja-liisa.hanninen@helsinki.fi.
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Hänninen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000382:microbiology*; D016123:Campylobacter jejuni / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D005387:Finland / Q000453:epidemiology; D014644:Genetic Variation; D016680:Genome, Bacterial; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058889:Molecular Typing; D058885:Multilocus Sequence Typing; D017385:Sequence Homology
chemical_list: D004269:DNA, Bacterial