Abstract
Background Campylobacter jejuni is the major cause of human bacterial gastroenteritis worldwide, and in a minority of cases, post-infectious complications may occur. ST-22 complex (usually Penner serotype 19) strains have been overrepresented among patients with postinfectious complications of campylobacteriosis. We here present a characterization of a collection of 27 Finnish C. jejuni strains of ST-22 complex, from humans (22 strains) and animal sources (five strains), with the aim of contributing to our knowledge of the pathogenesis of C. jejuni infections.Methodology/Principal FindingsAll strains were analyzed by pulsed-field gel electrophoresis (PFGE) genotyping, lipo-oligosaccharide (LOS) locus class, Y-glutamyl transpeptidase (GGT) activity, in vitro biofilm formation ability, invasion and adhesion in HeLa cells and induction of IL-8 production. ST-22 complex contained five STs (ST-22; ST-1947; ST-1966; ST-3892; ST-3996) which were homogeneous in having sialylated LOS class A1 but on the other hand were distinguished into two major lineages according to the major STs (ST-22 and ST-1947) by different PFGE genotypes and certain other characteristics. All ST-22 strains had similar SmaI PFGE profiles, were GGT positive, and formed biofilms, except one strain, while ST-1947 strains were all GGT negative, did not form biofilm, had significantly higher motility than ST-22 (p<0.05) and had their SmaI PFGE profile. Invasion and adhesion as well as induction of IL-8 production on HeLa cells were strain-dependent characteristics.Conclusions/SignificanceST-22 complex strains, reveal potential for molecular mimicry in host interactions upon infection as they all express sialylated LOS class A1. The two major STs, ST-22 and ST-1947 formed two homogeneous lineages, which differed from each other both phenotypically and genetically, suggesting that the strains may have evolved separately, perhaps by interacting with different spectra of hosts. Further studies are needed in order to understand if these two lineages are associated with different disease outcomes.
Highlights
Campylobacter jejuni is the most common bacterial cause of human gastroenteritis throughout the industrialized world
Genotyping of the strains pulsed-field gel electrophoresis (PFGE) analysis with SmaI subdivided the strains mostly according to their Sequence Types (ST) types (Figure 1) clustering ST-1947 and ST-22 strains into different branches of the tree
ST-22 complex have been detected among C. jejuni strains of human and animal origin in several countries, with a low frequency compared with many other clonal complexes [7,19,20,21,22,23]
Summary
Campylobacter jejuni is the most common bacterial cause of human gastroenteritis throughout the industrialized world. Genetic studies have shown that C. jejuni isolates which appear highly related based on their Multi Locus Sequence Types (ST) can have remarkable differences in their genomic content [2]. Multi Locus Sequence Typing (MLST) and the establishment of the international accessible MLST database (PubMLSThttp://pubmlst.org/campylobacter) [5], has offered an objective tool to analyse the diversity and global distribution of different ST complexes and types of C. jejuni. Certain ST-complexes, such as ST-22 (Penner serotype 19) and ST-403 (Penner serotype 23), have shown that they may represent clonal lineages among C. jejuni populations [6,7,8]. Campylobacter jejuni is the major cause of human bacterial gastroenteritis worldwide, and in a minority of cases, post-infectious complications may occur. We here present a characterization of a collection of 27 Finnish C. jejuni strains of ST-22 complex, from humans (22 strains) and animal sources (five strains), with the aim of contributing to our knowledge of the pathogenesis of C. jejuni infections
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