Longitudinal Study of Finnish Campylobacter jejuni and C. coli Isolates from Humans, Using Multilocus Sequence Typing, Including Comparison with Epidemiological Data and Isolates from Poultry and Cattle

Abstract

Campylobacter jejuni and C. coli are the most frequent causes of bacterial gastroenteritis in Finland (www.ktl.fi/ttr). The number of laboratory-confirmed cases has nearly doubled over a 10-year period (2,197 cases in 1995 to 4,002 cases in 2005). Campylobacter species are frequently isolated from a wide variety of sources, including poultry, cattle, pigs, sheep, cats, dogs, wild birds, and water. Most Campylobacter infections are sporadic, and the relative contributions of different sources of infection remain unknown. Risk factors for Campylobacter infection, as identified by case-control studies, include eating or preparing raw or undercooked meat, especially chicken meat, drinking unpasteurized milk or untreated water, contact with domestic animals and pets, and foreign travel (14,18,26). A recent case-control study (19) revealed swimming in natural bodies of water to be a novel risk factor. In addition, eating undercooked meat and drinking from dug wells were independent risk factors for domestically acquired Campylobacter infections in Finland (19).Discriminatory typing methods for use in the study of the molecular epidemiology and population genetics of Campylobacter isolates are crucial to better understand the epidemiology and ecology of the organism. Once such information is obtained, it could be used to develop intervention strategies to limit the numbers of human infections. Dingle et al. (6) developed a multilocus sequence typing (MLST) scheme for C. jejuni, which has been shown to be a valuable tool for studying the diversity and population genetics of Campylobacter isolates.

Identification of Potential Environmentally AdaptedCampylobacter jejuniStrain, United Kingdom

“…In a recent study, cases of ST-45 clonal complex were more associated with contact with pet dogs and cats than were other clonal complexes identifi ed (10); pet-mediated transmission of ST-45 might be supported in this study by the observed association of ST-45 with young children. Despite the evidence presented of a potential environmental transmission route for ST-45, it is also a type well recognized to colonize poultry (10)(11)(12), and the incidence among humans may be a result of consumption of seasonally contaminated poultry (2). However, the absence of strong early summer seasonality among other recognized chicken-adapted sequence types suggests that this is not the case (data not shown).…”

Genotypes and Antibiotic Resistances of Campylobacter jejuni and Campylobacter coli Isolates from Domestic and Travel-Associated Human Cases

“…This suggests that they might be the best adapted or most pathogenic for humans. Interestingly, as previously described (16), less than 2.0% of C. jejuni isolates belonged to CC45, which is the most common CC found in humans in most countries and especially in Finland (15,23). As poultry is supposed to be the main source of campylobacteriosis, the number of human isolates belonging to CC45 is remarkably low even though it was one of the most frequent CCs found in Swiss broilers (28).…”

“…The existing overlap of these two groups was due mainly to ST-21, ST-50, and ST-48 combined with flaB type 103, which were represented in both of them and which are the most frequent STs worldwide (15,16,18). Conversely, the new STs found among 2.6% of domestic strains, together with ST-3963, which was first described in isolates from Swiss broilers in 2008 and which also appeared among the domestic isolates, might represent clones that are endemic to Switzerland.…”

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

“…Twenty-one human isolates were analyzed by PCR-based MLST only. PCRs and sequencing of the seven MLST loci were performed as described in previous studies (12,23). Briefly, sequencing was carried out by BigDye Terminator v. 3.1 chemistry (Applied Biosystems, Foster City, CA), and sequencing products were run on an ABI Prism 3130XL genetic analyzer or an ABI 3730 DNA analyzer (Applied Biosystems).…”

“…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.…”