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%.

Multilocus Sequence Typing (MLST) and Whole-Genome MLST of Campylobacter jejuni Isolates from Human Infections in Three Districts during a Seasonal Peak in Finland

“…Eighty percent of all C. jejuni isolates in the present study were associated with three clonal complexes, ST-45 CC, ST-283 CC, and ST-677 CC, which were mainly represented by four STs (ST-45, ST-230, ST-267, and ST-677). When we compared the MLST data from our previous study (11), in which human C. jejuni isolates from 1996 to 2006 from the Helsinki metropolitan area were investigated, the frequencies of the two major CCs (ST-45 CC and ST-677 CC) were in accord with those in our present study. However, the frequencies of STs in district 2 differed significantly from our earlier data.…”

“…1). Compared to our previous C. jejuni MLST data, collected from 1996 to 2006 from domestically infected patients living in the Helsinki metropolitan area (11,12), the frequencies of the two major clonal complexes (ST-45 CC and ST-677 CC) were in line with those of districts 1 and 3. However, in district 2, ST-45 CC was not so common, and ST-677 CC, in turn, was overrepresented (P Ͻ 0.05) compared to that in other districts and our previous data (Fig.…”

“…Statistical tests were performed using SPSS software (IBM SPSS Statistics 21). The frequencies of the clonal complexes in each district were compared to our previous data collected in 1996,1999,2002,2003, and 2006 from the Helsinki metropolitan area (11,12). The Pearson chi-square and Fisher's exact tests were carried out by crosstabulations for each CC in districts 1, 2, and 3.…”

“…In our previous studies concerning the C. jejuni population structure and molecular epidemiology in Finland, large numbers of human C. jejuni isolates of domestic origin have been collected mainly from the Helsinki metropolitan area (11,12). In this study, Campylobacter isolates were collected from domestically acquired infections in three midsized districts located outside the metropolitan area.…”

Campylobacter sequence typing databases: applications and future prospects

“…Examples include: (i) the ST-45 and ST-257 clonal complexes, which are common amongst poultry in Europe, New Zealand and, to a lesser extent, Senegal de Haan et al, 2010a;Griekspoor et al, 2010;Habib et al, 2009a;Jorgensen et al, 2011;Kinana et al, 2006;Magnú sson et al, 2011;McTavish et al, 2009;Patriarchi et al, 2011;Wirz et al, 2010); (ii) the ST-61 and ST-42 clonal complexes, which have been found to be common amongst ruminants in This database depends on voluntary submissions and the data are, therefore, neither necessarily representative nor exhaustive; however, they do indicate that different clonal complexes show marked differences in the likelihood of being associated with particular isolation sources. Note that all clonal complexes are C. jejuni, with the exception of the ST-828 clonal complex, which is C. coli.…”