Delineation of Campylobacter concisus Genomospecies by Amplified Fragment Length Polymorphism Analysis and Correlation of Results with Clinical Data

Abstract

Campylobacter concisus has been as frequently isolated from human diarrhea as the important enteropathogen Campylobacter jejuni, but it also occurs in the feces of healthy individuals. The role of C. concisus in human disease has been difficult to determine, since the species comprises at least two phenotypically indistinguishable but genetically distinct taxa (i.e., genomospecies) that may vary in pathogenicity. We examined 62 C. concisus strains by amplified fragment length polymorphism (AFLP) profiling and correlated the results with clinical data. All C. concisus strains gave unique AFLP profiles, and numerical analysis of these data distributed the strains among four clusters. The clustering was of taxonomic significance: two clusters contained, respectively, the type strain (of oral origin) and a reference strain (from diarrhea) of each of the known genomospecies. Genomospecies 2 strains were more frequently isolated from immunocompetent patients and/or patients without concomitant infections that presented with fever, chronic diarrhea, and gut inflammation than was genomospecies 1, clustering with the type strain of oral origin. Bloody diarrhea was recorded only with C. concisus genomospecies 2 infections. We identified two additional C. concisus genomospecies: genomospecies 3 comprised a single strain from an immunocompetent patient, and genomospecies 4 contained five isolates from severely immunodeficient patients, i.e., organ transplantation recipients or those with hematological malignancies. All genomospecies 4 strains were of the same protein profile group and failed to react with a C. concisus species-specific PCR assay based on 23S rRNA gene sequences: the taxonomic position of this group requires closer investigation. Campylobacter concisus is genetically and taxonomically diverse and contains at least four distinct genomospecies that may exhibit differences in their spectra of virulence potential.

Campylobacter concisus as the etiologic agent of gastrointestinal diseases

“…6 There are also reports that the only potentially pathogenic bacteria isolated from the stool samples of patients with diarrhea was C. concisus. 19 So far, studies suggest that C. concisus may be an opportunistic pathogen, causing symptoms in predisposed patients. Hess et al described the case of a 55-year-old man with symptoms of gastrointestinal infection, with C. concisus as an etiological factor.…”

“…13 There are at least several different genotypes of C. concisus with different abilities to induce damage to the intestinal epithelial cells, and with various virulence and clinical pictures of the infection. 6,7,11,15,19,20 In in vitro studies, a C. concisus strain isolated from a child with newly-diagnosed Crohn's disease exhibited a greater ability to attach to and to invade the epithelial cells lining the intestine than strains isolated from patients with inflammation of the gastrointestinal tract. Furthermore, C. concisus strains isolated from healthy individuals were able to adhere to epithelial cells but lacked the ability to invade.…”

Delineation of genetic relatedness and population structure of oral and enteric Campylobacter concisus strains by analysis of housekeeping genes

“…Several previous studies have used different methods to group C. concisus strains based on their genetic differences (Bastyns et al, 1995;Istivan et al, 2004;Kalischuk & Inglis, 2011;On et al, 2013). A study by Aabenhus et al (2005) examined 57 enteric C. concisus strains and five oral C. concisus strains using amplified fragment length polymorphism (AFLP) and found that most of the C. concisus strains examined belonged to two genomospecies (genomospecies 1 and 2). Most recently, Miller et al (2012) analysed C. concisus strains using MLST analysis, in which they included C. concisus strains of different genomospecies from the study by Aabenhus et al (2005).…”

“…A study by Aabenhus et al (2005) examined 57 enteric C. concisus strains and five oral C. concisus strains using amplified fragment length polymorphism (AFLP) and found that most of the C. concisus strains examined belonged to two genomospecies (genomospecies 1 and 2). Most recently, Miller et al (2012) analysed C. concisus strains using MLST analysis, in which they included C. concisus strains of different genomospecies from the study by Aabenhus et al (2005). Miller et al (2012) found that their MLST method grouped Table 1.…”

Gastroenteritis caused by Campylobacter concisus

“…Most infected patients (71 %) were immunocompromised, as was our patient. C. concisus contains at least four distinct but phenotypically indistinguishable genomospecies that might exhibit differences in their spectra of virulence potential (Aabenhus et al, 2005), which may partly explain why so many persons infected by C. concisus do not develop gastrointestinal symptoms.…”