Investigation of motility and biofilm formation by intestinal Campylobacter concisus strains

Campylobacter jejuni and Campylobacter coli are the most common cause of acute bacterial gastroenteritis world-wide and as a result, they are the most widely studied Campylobacter species [1]. In recent years, a number of other Campylobacter species, including Campylobacter concisus, have emerged as gastrointestinal pathogens [2-4]. For example, C. concisus has been isolated from faecal samples and colonic intestinal biopsies of patients with both acute and chronic gastroenteritis and Crohn’s disease [5,6]. Although in comparison to C. jejuni relatively little is known about C. concisus, studies have shown that they share a number of similarities [7]. While both bacteria are spiral shaped and flagellated, C. jejuni can have single or bi-polar flagella, whereas C. concisus only has a single polar flagellum.Bacterial flagella are complex, highly refined organelles that allow bacteria to swim through fluids, including viscous environments, and which also play a central role in adhesion to and invasion into host cells [8]. In the well-established pathogen C. jejuni, flagellar motility has been reported to be a key pathogenicity factor [9], with early studies showing that C. jejuni was capable of colonising the mucus layer and intestinal crypts filled with mucus [10]. Further, the flagellum of C. jejuni has been shown to assist in bacterial adhesion to epithelial cells [11]. Scanning electron microscopy (ScEM) studies have shown that C. concisus adheres to the intestinal epithelium by wrapping its flagellum around the microvilli of intestinal epithelial cells [5,12]. Although the importance of motility in C. concisus has yet to be described, current data would suggest that the flagellum may be an important pathogenicity factor in C. concisus infection [5,12].Bacterial flagella have also been shown to be involved in biofilm formation [13,14]. The ability to form biofilms through the complex interaction of bacteria has been reported to be important for bacterial survival w