title: Decreasing trend of overlapping multilocus sequence types between human and chicken Campylobacter jejuni isolates over a decade in Finland.
abstract: We describe the long-term multilocus sequence typing (MLST) analysis of the population structure and dynamics of 454 Finnish human Campylobacter jejuni isolates, as well as 208 chicken isolates, collected during the mid-1990s to 2007. The sequence type clonal complexes (ST CC) ST-45 CC, ST-21 CC, and ST-677 CC were the most common ones found among all isolates, and they covered 73.9% of all isolates. The ST-283 CC also was found frequently among chicken isolates (8.2%). The predominant STs among all isolates were ST-45, ST-50, and ST-677. ST-137 and ST-230 were common among human isolates, and ST-267 was found more frequently among chicken isolates than human isolates. The ST-45 CC was significantly associated with chicken isolates (P < 0.01), whereas the ST-21 CC was associated with human isolates (P < 0.001). The ST-677 CC was not associated with any host (P = 0.5), and an opposite temporary trend of this complex was seen among chicken and human isolates, with an increase in the former and a decrease in the latter during the study period. Furthermore, the ST-22 and ST-48 CCs were significantly associated with human isolates (P < 0.01), but neither of the CCs was found in chicken isolates. The annual overlap between STs from human and chicken isolates decreased from 76% at the beginning of the study to 58% at the end. Our results suggest that the importance of chicken as a reservoir for strains associated with human infections has declined despite the consumption of domestic chicken meat increasing during the follow-up period by 83%.
authors.affiliation: Department of Food Hygiene and Environmental Health, P.O. Box 66, FI-00014, University of Helsinki, Finland. astrid.dehaan@helsinki.fi
authors.forename: C P A
authors.initials: CP
authors.lastname: de Haan
authors.forename: R
authors.initials: R
authors.lastname: Kivistö
authors.forename: M
authors.initials: M
authors.lastname: Hakkinen
authors.forename: H
authors.initials: H
authors.lastname: Rautelin
authors.forename: M L
authors.initials: ML
authors.lastname: Hänninen
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques; D002169:Campylobacter Infections / Q000453:epidemiology* / Q000382:microbiology / Q000662:veterinary*; D016123:Campylobacter jejuni / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D002645:Chickens / Q000382:microbiology*; D016000:Cluster Analysis; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005387:Finland / Q000453:epidemiology; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D015995:Prevalence; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial